This document contains information about new and changed features in this version of Compaq C++ for Tru64 UNIX.

Compaq Computer Corporation
Houston, Texas

© 2001 Compaq Computer Corporation.

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Contents

1 Introduction

This document contains the release notes for Compaq C++ Version 6.3 for Compaq Tru64 UNIX.

This kit installs two compilers:

• The cxx command invokes the Version 6.3A compiler.
• The cxx -oldcxx command invokes the 5.7 compiler. The version is V5.7-002. This compiler will not be included in future kits.

  Note The Version 5.7 compiler's lack of support for 128-bit long doubles can cause crashes on Compaq Tru64 UNIX Version 5.0 or later.

HTML files are provided for the release notes and some of the product manuals for use with a web browser. You can install these files by selecting the subset Compaq C++ HTML documentation .

To view this documentation, point your browser to file:/usr/share/doclib/cplusplus/index.htm

2 Important Compatibility Information

Compaq strives to maintain a high degree of compatibility between successive versions of the compiler and its run-time environment. Because, however, each new version includes enhancements and changes, you should be aware of the following whenever you upgrade:

• Differences between Run-Time Library versions
• Differences between compiler versions
• Difference between Compaq C++ and the C++ International Standard

The next sections discuss these differences.

2.1 Run-Time Library Differences

Applications must use a version of the C++ Run-Time library ( libcxx ) that provides all the functions they require. If an application is linked shared, and the correct library version is not installed, "undefined symbol" error messages appear at run time. Changes in the Run-Time Library occurred in Versions 6.0, 6.2, and 6.3.

Any code that references the C++ Standard Library (any of the STL containers or algorithms, standard iostreams or locales) must be recompiled and relinked. This restriction does not apply to code that references the pre-standard class library, because the stability of that library's interface guarantees link compatibility in future releases.

For information about redistributing the C++ Run-Time Library, see Deploying Your Application in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

2.2 Compiler Differences

Starting with Version 6.0, the Compaq C++ compiler differs significantly from previous versions. There are several major differences that you should be aware of before using a Version 6.n compiler for the first time. These differences are summarized here. For more detailed information, see Porting to Compaq C++ in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

• Language differences
  The compiler implements most of the C++ International Standard, which differs significantly from the language specified in the ARM (The Annotated C++ Reference Manual, 1991, by Ellis and Stroustrup) with some ANSI C++ extensions. When switching from a Version 5.n compiler, you might need to modify your source files, especially if you use the default language mode. In addition, language changes can affect the run-time behavior of your programs. If you want to compile Version 5.n source code with minimal source changes, specify the -std arm option. See Porting to Compaq C++ in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
  If Version 6.n requires excessive changes to your applications even when you use the -std arm option, or if you encounter problems using the Version 6.n compiler, you can compile using the cxx -oldcxx command. If you discover a compatiblity problem that is not documented, please file a PTR or SPR.
• Diagnostic differences
  The Version 6.n compiler does more error checking than Version 5.7 and generates more diagnostics. If you want the number of diagnostics issued by the Version 6.n compiler to be similar to Version 5.7, compile with the -msg_quiet option. For details, see Message Control Options in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Implementation differences
  The automatic template instantiation model has been redesigned for the current version. Although code compiled with Version 5.n and 6.n compilers can be combined, you must complete the Version 5.n instantiation process with a Version 5.n (or specify the -oldcxx option) before linking with code compiled with Version 6.n. See Using Templates in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

The export keyword for templates (Standard §14, paragraph 6; Stroustrup §9.2.3) is not supported in Version 6.3 but will be supported in a future version:

3 Release Notes for the C++ Compiler

The following sections describe enhancements, changes, problems corrected, and restrictions for the C++ compiler.

3.1 Enhancements, Changes, and Problems Corrected in V6.4

The compiler supports C/C++ OpenMP Version 1.0. C++ exception handling within an OpenMP parallel region is not initially supported but will be supported in a later release.

3.2 Enhancements, Changes, and Problems Corrected in V6.3-011

• A multithread safety problem which can lead to corruption or deadlocking when using the C++ standard library iostreams and locales has been fixed.(L1625)
• The iversion string for libcxx.so has been updated to work around a bug in the loader in Tru64 V5.1 that prevented the library from being loaded.(8638)
• The compiler no longer aborts when using pointers to members.(8632)

• The compiler no long aborts when processing a class that imports a set of overloaded delete operators from a base class with a using-declaration or an access declaration. (8611)

• The compiler no longer generates __init_sti names incorrectly which was resulting in duplicate symbols. (8568)
• The demangler no long crashes on names beginning with __INTER. (8553)
• The archive version of libdemangle has been added to the kit. (8553)
• The compiler no longer crashes when -xref is used and duplicate templates are encountered. (8501)
• The compiler no longer encounters a catastrophic error on a conditional operator. (8481)
• The compiler no longer encounters a catastrophic error on a virtual base class. (8477)
• A multithread safety problem which can lead to corruption or deadlocking when using the C++ standard library iostreams and locales has been fixed.(L1561)

• The compiler no long generates identifier undefined warnings in <math.h> when compiling -fast with Unix standard macros.

• The GEM backend was upgraded.
• Documentation updated to reflect 6.3A release.

• Components of the "-oldcxx" compiler are now in the appropriate subset.
• Fixed arch EV68 support.

• The compiler no longer generates an error when compiling pthreads.h with "-std strict_ansi."
• The GEM backend was upgraded.

• The compiler no longer generates a compiler memory access violation for a local function declaration inside a member function with the same name as a virtual and a non-virtual function in the function's base class.
• The compiler no longer generates a memory access violation when it sees a reference to a <cname> structure in a function prototype before the <cname> structure is declared.

Enhancements, changes, and problems corrected are as follows:

• This version of the C++ compiler implements C++ headers for C Library Facilities. The <cname> headers avoid pollution of the global namespace by defining all C names only in namespace std . (See Stroustrup, §9.2.2 and §16.1.2.)
  The <cname> headers are located in the directory /usr/include/cxx_cname .
  If you include a <cname> header and use the -pure_cname option, all C functions and types found in that header file are declared only in namespace std , as specifed by the C++ International Standard.
  Specifying the -nopure_cname option causes <cname> headers to be handled as if the corresponding <name.h> version had been included. That is, names are available both in namespace std and global scope.
  The default is -pure_cname when compiling with -std strict_ansi and -std strict_ansi_errors . The default is -nopure_cname when compiling with -std ansi , -std arm , -std gnu , -std ms , and -std cfront .
  The compiler search order for include files has been changed from

  /usr/include/cxx
  /usr/include

  
  to

  /usr/include/cxx
  /usr/include/cxx_cname
  /usr/include

  
  Including <name.h> after including the corresponding <cname> header brings all names declared in that <cname> header into global namespace with "using std::name " declarations.

  New Header Files and protect_headers_setup
  
  The addition of <cname> headers adds several new files and the new subdirectory /usr/include/cxx_cname . If you are using protect_headers_setup on your system, you might need to rerun it after installing or upgrading to the Compaq C++ Version 6.3 compiler. For more information, see the protect_headers_setup(8) reference page or Protecting System Header Files in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

  Backward Compatibility
  
  In -pure_cname mode, <cwchar> does not include <cstdio> . Therefore, printf() is not declared unless <cstdio> is included.
  For example, the vfwprintf function, declared in <cwchar> , requires that <cstdarg> and <cstdio> be included:

  int vfwprintf(FILE *, const wchar_t *, va_list);

  
  New overloaded function signatures have been added to several <cname> headers (see Standard §21.4, §25.4, and §26.5). These overloaded signatures have been made available when including the <cname> header in -pure_cname mode. If the __CNAME_OVERLOADS macro is defined, the new signatures are available in both -pure_cname and -nopure_cname modes. On some operating system platforms, defining the __CNAME_OVERLOADS macro in -nopure_cname mode in combination with other macros and options (for example, -ms , -D_XOPEN_SOURCE ) can cause compile errors.
  cmath (Standard §26.5) now provides float and long double overloaded signatures for math functions in -pure_cname mode, or in -nopure_cname mode with the __CNAME_OVERLOADS macro defined. On some operating system platforms, defining the __CNAME_OVERLOADS macro in -nopure_cname mode in combination with other macros and options (for example, -ms , -D_XOPEN_SOURCE ) can cause compile errors.
  These added signatures could cause type ambiguity problems or different runtime behaviour in existing code. Consider theses examples:

  • sin(1) is now ambiguous because overloads are provided for float, double, and long double. A user sees the following differences, because the argument of sin(1) is assumed to be of type int :

    cout << "sin(1) = " << sin(1) << endl; // generates an error cxx: Error: t.cxx, line 15: more than one instance of overloaded function "sin" matches the argument list: function "std::sin(long double)" function "std::sin(float)" function "std::sin(double) C" argument types are: (int) cout << "sin(1) = " << sin(1) << endl; -----------------------^

  • The type of the argument to an overloaded math function determines the type of its return value and associated precision. Calls to math functions using float or long double arguments may return less precise or more precise values than previously. Compare the following:
    • Previous compiler release:

      long double ldout = sin(1.0); ldout = 0.84147098480789650000

    • Current compiler release:

      long double ldout = sin(1.0); // type int argument - ambiguous long double ldout = sin(1.0l); // type long double argument ldout = 0.84147098480789650000 long double ldout = sin(1.0f); // type float argument ldout = 0.84147095680236816000

  
  Signatures have been added in cstring , cwchar , and cstdlib header files for the following functions:

  cstring: (Standard §21.4) strchr, strpbrk, strrchr, strstr, memchr
  cwchar: (Standard §21.4) wcschr,wcspbrk, wcsrchr,wcsstr, wmemchr
  cstdlib: (Standard §25.4) bsearch, qsort , (§26.5) abs, div

  
  The added signatures could cause problems in existing code. For example, because char* strchr(const char*, int) now has overloads const char* strchr(const char*, int) and char* strchr(char*, int) , the following code does not work:

  #include <cstring> void f(char*) {;} int main() { f(strchr("abc",1)); // strchr returns a const char* return 0; }

• The -t option has two new variants, -ti (include C++ header files) and -tj (include cname header files).
  For a complete description of the -t option, see the cxx(1) reference page.
• In strict_ansi mode, the name of a class is now entered as a member of itself, as required by clause 9 (para 2) of the Standard; this behavior is implemented more or less as an implicitly declared member typedef and might cause some existing programs to fail. For example:

  namespace std { class iterator {}; } struct tree { struct iterator {}; struct nested : public std::iterator { // Compaq C++ 6.2 and below thinks this is tree::iterator // Compaq C++ ?? in strict_ansi mode thinks this is std::iterator nested(const iterator&); }; };

  
  [6613]

• The error "incompatible parameter", issued when there is a difference in sign between pointers, has been made discretionary. As a result you can now reduce/increase the severity of this message or enable/disable it using its error tag incompatibleprm or its error number. The same can also be done by enclosing the offending code in #pragma. For Example, the error message for the following program can now be controlled.

  void f(unsigned int *i) { } void main() { f((int *)0x05); }

  
  In addition, specifying -std gnu reduces the message severity to warning.

The following restrictions apply for the current release:

• In Version 5.n, if you allocate an array of objects of a class type with a constructor but without a destructor using new[n] , you will be unable to deallocate this object using delete[] in a module compiled with Version 6.n because the hidden count was not stored during the allocation. [7232]
• Because the task library is being retired, it is no longer a shared object. You must therefore specify -threads -lcmalib on the cxx command line in addition to -ltask for the link. [7976]
• A template mangling problem can occur if you use class template partial specializations with non-type template arguments in the compiler's model arm mode.
  For example, the following program produces a compilation error:

  template <int i, int j> struct C {}; template <int i, int j, class S> struct D {}; template<int Dim1, int Dim2, int Dim3> struct D<Dim1, Dim2, C<Dim1, Dim3> > { void foo(); }; template<int Dim1, int Dim2, int Dim3> struct D<Dim2, Dim1, C<Dim1, Dim3> > { void foo(); }; int main() { D< 1, 2, C<2, 1> > d; d.foo(); D< 2, 1, C<2, 1> > d2; d2.foo(); return 0; }

  
  The problem occurs because the two instantiations of foo() are incorrectly mangled identically. As shown in the example, this happens when the template parameter list is instantiated with the same arguments in the same order, but the template argument list is actually different.
  If the calls to D<...>::foo() were made from two different source files, the compiler would not give an error; instead it would incorrectly call the same instantiation for both calls.
  This problem cannot be corrected without breaking link compatibility with objects produced from the previous releases. The name is mangled correctly in the compiler's model ansi mode. For more details on the model ansi compiler option, see the description of the -model [ansi | arm] option in the cxx.1 reference page. [8012]

• A problem in libexc on Tru64 UNIX before Version 4.0E generates an error message when an exception is thrown from a constructor that will be called by a static initialization, as in the following example. The error message appears after the example. There is no workaround for the problem.

  #include <stdio.h> #include <exception> #include <stdlib.h> void term_handler() { printf("in terminate handler\n"); abort(); } class C { public: C() { std::set_terminate(&term_handler); throw 5; } }; C c; int main() { return 0; }

  
  The code generates the following error message:

  exception system: exiting dues to multiple internal errors: exception dispatch or unwind stuck in infinite loop exception dispatch or unwind stuck in infinite loop

  [CPP 5021]

Enhancements, changes, and problems corrected are as follows:

• In certain cases, dynamic initialization of a static variable of aggregate type with an initializer list containing both constant and non-constant values did not occur correctly. Aggregate members initialized with constant values were initialized with 0, not with the constant values. Consider this example:

  const float x = 3; struct S { static long *_GetEntries() { static long _entries[] = { 2, (long)x, 8 }; return _entries; } }

  
  In this example _entries[0] and _entries[2] were not initialized correctly to 2 and 8, respectively. Instead, the fields were both were incorrectly initialized to 0.
  The compiler inserts code into _GetEntries to initialize _entries the first time _GetEntries is called. Because it failed to insert the initializing code correctly, the code that initialized members with contant values was not being executed.

Enhancements, changes, and problems corrected are as follows:

• In certain cases, dynamic initialization of a static variable of aggregate type with an initializer list containing both constant and non-constant values did not occur correctly. Aggregate members initialized with constant values were initialized with 0, not with the constant values. Consider this example:

  const float x = 3; struct S { static long *_GetEntries() { static long _entries[] = { 2, (long)x, 8 }; return _entries; } }

  
  In this example _entries[0] and _entries[2] were not initialized correctly to 2 and 8, respectively. Instead, the fields were both were incorrectly initialized to 0.
  The compiler inserts code into _GetEntries to initialize _entries the first time _GetEntries is called. Because it failed to insert the initializing code correctly, the code that initialized members with contant values was not being executed.

• When generating EV6 code, the peephole optimizer could display an assertion failure complaining that an operand is not fixed or not float. This has been corrected. [6787]
• When generating EV6 code, the compiler produced a code pattern (specific to conversion between integer and floating types) that could produce incorrect results. This release corrects the problem. [6816]
• If the exception handling mechanism calls the two-parameter delete operator to clean up an allocated object that had an exception in the constructor, the mechanism now passes the correct size to the second (size) parameter. [6823]
• When compiling with -std arm , C++ treated the types const char *& , and char *& as equivalent. Effects-compatible types did not recognize this behavior. A new ARM-compatible flag for types_are_compatible with effects_compatible_types is now set when in ARM mode. The new flag specifies that all type qualifiers are ignored when comparing the type compatiblity of two pointer or reference types. [6949]
  The ARM mode of the compiler allows a const char * reference to reference a char * object, as show in the following example:

  static char * f() { char *value = 0; const char * & d1 = value; // d1 can reference value d1 = "abc"; // changes value return value; // should return "abc", not 0 }

  
  In standard mode, however, this behavior is not allowed, and the compiler did not recognize that assignments to the reference change the value of the object referenced. In the example, because the compiler did not recognize that assignments to d1 would change value, it assumed that the assignment to d1 did not occur and that the correct return value fo the function f() was 0.
  This version of the compiler fixes the problem.

• A change in the debugging symbol table produced by the C++ compiler causes all namespace members to be generated in the local symbol table of the file descriptor associated with the namespace, within the scope of the namespace. This change make it easier to debug namespaces. [LDB1569]

Version 6.2 includes the following enhancements and changes:

• Some functions needed for language compatibility run-time support have been moved from libcxxstd.a to the shared library libcxx.so . For details, see Deploying Your Application in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Many compiler and library problems have been corrected (see Section 3.15 and Section 4.5).
• Many improvements have been made to cross-reference information generated by the compiler.
• The compilation system and run-time library now call destructors that are defined in shared images which have been closed correctly using dlclose() , with the linker option -depth_ring_search . This feature requires that a new libcxx be installed on your system with Version 6.2. Otherwise, the compiler reports the undefined symbol __cxx_call_static_dtors .
• The -gall option now outputs debugging information about unused variables, so that you can queries the debugger about them. For more information about this option, see Using the -gall and -gall_pattern Options in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Debugging support for constant variables is improved. Although the compiler does not generate debug information for constant externs (because you might not be able to link), it does generate debug information for all constant variables whose underlying type is int or float
• Diagnostics from the driver during the link phase are now sent to stderr instead of to stdout .
• Consumption of virtual memory is significantly reduced when computing the addresses of deeply nested virtual base classes. [6473]
• The compiler diagnoses more cases of unreachable code. If you receive warnings you believe to be inappropriate, please report them. [6534]

This section summarizes compiler changes and the most important problems corrected in Version 6.2.

• Specifying -noglobal_array_new no longer causes generation of rogue cleanup handlers. [6095]
• Enum types larger than int are now supported when compiling with -std arm . [4499]
• Specifying -v now displays command-line, driver-generated, and predefined macros on standard output. The listing file now contains correct list of command-line and predefined macros, taking into account macro undefines and redefines. [4723] [5609]
• Within a template member function instantiation, the compiler now correctly calls a function with short pointer in -xtaso_short mode. The compiler no longer displays an error for the call.
• Some compiler-generated wrapper functions with the __STF____default_version prefix were not resolved in template automatic instantiation mode. The problem is corrected. [6362]
• Debugging support is now provided for anonymous union variables inside namespaces. In the following example, debuggers support referencing s.a and s.b :

  struct S { union { int a; int b; } } s;

  
  In the following example, the compiler generates two variables, x and y , which the debuggers can examine.

  union { int x; char y[4]; };

  
  The compiler no longer generates tag names for tagless structs and unions.

• Under the following conditions, the compiler could generate code that returned the value of i before the store of the new value:
  1. Take the address of a variable, using a type other than the variable's type,
     (p = (char *)&i) .
  2. Assign to the variable using a pointer addition expression, *(p + 0) = new_value .
  3. Fetch the variable's value directly (return i) .
  
  The problem can occur only if the store using the pointer addition expression appears within an if statement, as in the following code:

  int f(int flag) { int len = 1; if (flag) { char *ppp = (char *)&len; *(ppp + 0) = 2; }; return len; }

  
  The problem has been corrected. [6421]

• Bad code is no longer generated for an array reference within a template instantiation. [6394]
• The compiler no longer generates incorrect code for offsets to external arrays. [6386]
• The routine for new[] now calls delete[] if an exception occurs during construction. [6243]
• A compiler crash caused by a label statement in a switch statement has been corrected. [6614]
• Macro expansions are now output to the listing file when both -show expansion and -source_listing are specified. [6107]
• When a local stack is used in constructors, the compiler displays the warning "Initialization of references requires temporaries of automatic storage duration". [4522]
• Null characters in comments are now ignored in -std arm mode. The Version 6.0 compiler treated null characters in comments as errors. Outside of comments, null characters are now diagnosed as warnings in -std arm mode, and as errors otherwise. [3740]
• The compiler has implemented the _poppar builtin function and added code to convert output type for _poppar , _popcnt , _leadz , and _trailz to match contents of the UNIX builtins.h file. See Built-In Functions in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• A template class name can now be reused as a nontemplate class in a private namespace without generating an error message. [6541]
• A Version 6.0 bug caused the the compiler to emit a union layout incompatible with earlier versions if the union contained bitfield of size 8, 16, 24... up to the size of the type for the bitfield. For example:

  typedef struct size4 { union { unsigned ttn :8; struct { unsigned incr :3; unsigned rep :5; } v1; } u; } size4;

  
  The size of size4 is 4 bytes for Version 5.7, and was incorrectly set to 1 since Version 6.0. This bug is fixed in Version 6.2. If you have such a bitfield in your code, you must recompile. [6567]

• If -nocleanup is specified, the compiler does not reference the destructors or delete operators used for cleanup code that is not generated. The -noexceptions option now implies -nocleanup . [6216]
• -std arm mode, the compiler no longer generates code to the left side of the -> and . operators if the right hand operand is a static member. [4469]
• For compatibility with Version 5.6, the ec_inaccessible_base_class error on function return expressions in -std arm mode is now disabled. [3744]
• The compiler now warns about differences in meaningless qualifiers.
• The driver now terminates if the compilation results in a fatal error or ctrl-c .
• In -std arm mode, the compiler no longer checks for suitable copy constructors of classes with volatile qualifiers. [6087]
• To maintain compatibility with arm , cfront , and ms modes, null preservation code is enabled for cases where a pointer should not be null. [4695]
• The compiler now checks for comparison of two incompatible enums. The compiler reports this condition with a new informational message ec_incompatible_enum_comparison . [6172]

This release is not totally compatible with previous versions; source changes might be required. The following general restrictions apply for the current release:

• The C++ International Standard permits overriding a virtual member function based only on a derived class return type. The current release does not support this capability.
• Intrinsic bcopy generates warning
  Starting with C++ Version 6.2, the bcopy function has been made intrinsic to improve performance. On Compaq Tru64 UNIX Version 4.n systems, this change can cause the compiler to issue the following warning message:

  cxx: Warning: /usr/include/strings.h, line 83: Expected type "void (const void *, void *, unsigned long) C" is incompatible with declared type "void (const char *, char *, int) C", function will not be made intrinsic extern void bcopy __((const char *, char *, int)); ------------^

  
  Compaq Tru64 UNIX Version 4.n systems provide two function prototypes for bcopy , one that conforms to the standard, and another, the system default, for compatibility with previous operating system versions. The compiler issues the warning when it encounters the nonstandard version. For details, see the bcopy(1) reference page.
  To suppress the message, you can do one of the following:

  • Use an ANSI-standard copy function such as memcpy
  • Enable the standard function by defining -D_XOPEN_SOURCE_EXTENDED -D_OSF_SOURCE before including the header file
  • Compile with the -std strict_ansi option
  • Use #pragma function(bcopy)
  
  Because the next major operating system release implements a change in the UNIX98 standards and provides only the standard definition, the first or second method is recommended. The third and fourth methods prevent the function from being made intrinsic, resulting in degraded performance.
• Some features implemented in Version 5.7 are not supported by the current compiler. See Porting to Compaq C++ in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Some objects might have their exception unwinding information set to a negative index in the cleanup table, resulting in a core dump at runtime if an exception is raised. [7091]
• The UNIX utility nm does not always work on Compaq Tru64 UNIX Version 4.n systems with object files generated by the current compiler. The symptom is a seg fault when nm attempts to dump its list. An alternative to nm might be the odump utility. For example, the command odump -tv foo.o lists all the symbols in the archive. See the odump reference page for more details on the odump utility. Another possible workaround is to compile your object file with -g (debugging), then recompile it without -g . That procedure might avoid triggering the nm bug.
  If you want to obtain a version of nm that corrects this problem, these are the patch kit identifiers:
  

  OPERATING SYSTEM VERSION	PATCH ID
  v40	OSF400-438
  v40a	OSF405-438
  v40b	OSF410-438
  v40c	OSF415-438
  v40d	OSF420-42

• If you use a non-default pointer size or member alignment and header files are not protected, the following warning is issued:

  < cxx: Warning: A non-default pointer size or member alignment is specified and the system header files are not protected. This may yield unpredictable results. The protect_headers_setup script can help. See the protect_headers_setup(8) reference page for details.

  
  The protect_headers_setup(8) reference page page is planned for a future release of Compaq Tru64 UNIX. For now, see Protecting System Header Files in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

• Restricted address space size for precompiled headers in some versions of Compaq C++.
  Some versions of Compaq C++ might restrict the size of the address space available for use by precompiled headers. If the compiler terminates with a message about mapped memory, this may be the problem.
  To increase the address space available for precompiled headers you need to increase the mapentries limit.
  Follow these steps to change the mapentries limit:
  1. Become the root user.
  2. Create a new file named /tmp/xxx and insert the following lines:

     vm: vm-mapentries=5000

  3. Execute the sysconfigdb command as follows:

     # /sbin/sysconfigdb -f /tmp/xxx -m vm

  4. Reboot the system.
  
  This procedure increases the mapentries limit from the default 200 to 5000. Increasing the limit by that amount has no adverse effect on the system.
• When using PCH, the line number associated with an inline function is the line at which the PCH stop is encountered.
• Certain utilities, such as GNU Make, do not recognize compressed object files, which the compiler creates by default. If you encounter problems, you can specify the -nocompress command-line option.
• Instantiating function templates with array types can result in different external name encoding than with C++ Version 5.n. To avoid link errors, recompile the template definition with the current version of the compiler.
• Linker -no_archive does not work with Compaq C++
  The switch does not work because the Standard Library, libcxxstd.a , is supplied only in archive form.
  Specifying -no_archive causes the cxx drive to issue the following messages:

  ld (prelink): Can't locate file for: -lcxxstd ld: Can't locate file for: -lcxxstd

• Class and Standard Libraries generate Third Degree messages. Appendix C in Using Compaq C++ for Tru64 UNIX and Linux Alpha describes these messages.

This section summarizes compiler changes, enhancements, and the most important problems corrected in Version 6.1-029.

• The optimization phase of the compiler has been changed to disable a specific optimization that caused ATOM based tools to behave unpredictably. This optimization may be restored once these tools have been enhanced to expect this optimization.
• New warning messages indicate when assigning from a larger to a smaller data type might cause a truncation. These messages facilitate porting from 32-bit to 64-bit platforms. [3971]
• A workaround has been implemented to prevent the linker from erroneously declaring too many GOTs during the prelink phase. [6027] [43-4-305]
• Templates made friend are now instantiated with external linkage when -timplicit_local is specified. [6056]
• Access checking for pointer to members in ARM mode has been relaxed to be more compatible with Version 5.n. [6088]
• Calling operator(new) on an array of objects allocates extra header information to describe the array so that operator delete can call destructors on the elements. In this release, the header has been made compatible with object code generated with version 5.n releases. [6151]
• During the prelink phase, the driver no longer splits linker output lines at 8000 characters. [6166]
• The driver no longer suppresses error messages during the prelink phase. As a result, messages might apprear multiple times. This new behavior helps prevent silent or confusing failures. [6168]
• A problem unwinding from multiple exceptions has been corrected. [6185]
• A compiler fatal error using volatile structures has been corrected. [6186]
• The cxx driver no longer runs post-link phases that are unnecessary to determine required templates. [6191]
• A problem with interaction between -vptr_size_short and -xtaso_short has been corrected. [6195]
• If a local static object is referenced by more than one template, the compilation no longer results in an unresolved symbol for the __fini routine. The routines to call the destructors for static objects, which are prefixed with __fini , are now allocated properly with automatic instantiation mode. [6278]

This section summarizes compiler changes, enhancements, and the most important problems corrected in Version 6.1.

• The Version 6.0 compiler incorrectly mangled the name of a class virtual function table when that class was nested within another class or namespace. If object modules compiled with Version 5.n and Version 6.0 were linked together, the compiler might display the following message:

  ld: Unresolved: std::__vtbl_3std9type_info

  
  This problem has been corrected. Any code generated with Version 6.0 that demonstrates this problem should be recompiled with the current compiler. [5144]

• The compiler used to mark all member functions of the class that had not already been specialized as needing to be instantiated when processing a #pragma define_template class <args> . But the compiler did not instantiate the functions until processing the end of the scope. If a specialization occurred after the #pragma but before the compiler tried to instantiate it, the compiler found that the member function had already been specialized and reported the following error:

  "function" cannot be instantiated -- it has been explicitly specialized

  
  This error is reduced to a warning and is issued only once per instantiation. The warning can be suppressed by using the command-line switch -msg_disable 490 . See Compaq C++ Implementation in Using Compaq C++ for Tru64 UNIX and Linux Alpha . [43-4-137]

• The compiler no longer generates incorrect code when dereferencing an element of an array of pointers. [5236]
• A problem creating shareable libraries has been corrected by allocating static local const variables initialized with pointers to .rdata instead of to .rconst . [43-4-166]
• To facilitate setting default compiler flags, you can now create an optional configuration file named comp.config or an environment variable named DEC_CXX .
  • The comp.config file allows system administrators to establish a set of compilation flags that are applied to compilations on a system-wide basis. The compiler flags in comp.config must be specified on a single line, and the comp.config file should be stored in the compiler target directory, /usr/lib/cmplrs/cxx .
  • The DEC_CXX environment variable allows users to establish a set of compilation flags that are applied to subsequent compilation on a per user basis.
    The DEC_CXX environment variable can contain two distinct sets of compilation flags separated by a single vertical bar ( | ). The flags before the vertical bar are known as prologue flags and the flags after the bar are know as epilogue flags.
    The DEC_CXX environment variable can begin or end with a vertical bar, or have no vertical bar at all. If no vertical bar is present, the flags are treated as prologue flags by default. Any vertical bar found after the first vertical bar is treated as whitespace and a warning is issued.
  
  During a compilation, compiler flags are processed in the following order:
  1. comp.config flags
  2. DEC_CXX prologue flags
  3. command line flags
  4. DEC_CXX epilogue flags
  If -v is specified on the command line, the contents of DEC_CXX and comp.config , if present, are displayed. [4488]
• By default, C files are compiled with -std . Users can now override the default by specifying
  -std0/-std1 . [4392]
• The compiler no longer mishandles "?" operations on a boolean type in constructs like that in the following example. [43-4-135]

  bool f(int i) { return (i<5 ? false : true ); }

• Parallel compiles now work correctly because the compiler no longer deletes an empty template repository. [5544]
• The current version does not support the -show statistics option implemented in Version 5.7.
  The following are now supported:

  -nocpp
  -show expansion
  -xref
  -xref_stdout
  listing of predefined macros
  #pragma message

This section briefly summarizes changes and enhancements made in Version 6.0. For information about compatibility issues that you might encounter using Version 6.2 if you have used Version 5.n in the past, refer to Porting to Compaq C++ in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

• Support for the C++ International Standard (with some differences, as described in Section 2.3), including the C++ Standard Library. See Section 4 for information about and changes to the Standard Library.
• Language mode options
  For compatibility with previous versions, the compiler supports an ARM language mode and provides both -std ansi and -std arm language mode options, as well as options to support other C++ dialects. For details, see Porting to Compaq C++ in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Improved automatic instantiation of templates, including fewer restrictions. In particular, Compaq C++ no longer requires that template declarations and definitions appear in header files. For details, see Using Templates in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Support for precompiled headers to decrease compilation times. For complete information, refer to Precompiled Headers in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Performance optimization options
  To improve performance, the compiler provides the following options:
  • -[no]ansi_alias
  • -assume [no]pointers_to_globals
  • -assume [no]whole_program
  
  For details, see the cxx(1) reference page .
• Run-Time type identification
  The compiler emits type information for Run-Time type identification (RTTI) in the object module with the virtual function table, for classes that have virtual function tables. For details, see Run-Time Type Identification in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Changes to behavior of the -gall option. See Using the -gall and -gall_pattern Options in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

The following sections describe enhancements, changes, problems corrected, and restrictions for the C++ Standard Library. For information about the Compaq C++ Class Library, see Appendix A in Using Compaq C++ for Tru64 UNIX and Linux Alpha .

The current version of Compaq C++ implements the new Standard Library string class, known as the String Library. Do not confuse this class with the String Package, which is part of the DEC C++ Class Library implemented in earlier versions of Compaq C++.

Portions of the ANSI C++ Standard Library have been implemented in Compaq C++ using source licensed from and copyrighted by Rogue Wave Software, Inc. Information pertaining to the C++ Standard Library has been edited and incorporated into Compaq C++ documentation with permission of Rogue Wave Software, Inc. All rights reserved.

Portions copyright 1994-1999 Rogue Wave Software, Inc.

4.1 Enhancements, Changes, and Problems Corrected in Version 6.3

Version 6.3 includes the following enhancements:

• The tree data structure, which sets and maps usage, has been refined to decrease the amount of space allocated for small element size containers. [10.1475]
• To ensure thread safety, the basic_string reference count used to be protected by a mutex, which called thread locking and unlocking routines. Performance of this class in multithreaded applications has been improved by changing the implementation to use instead atomic builtins (see Appendix B in Using Compaq C++ for Tru64 UNIX and Linux Alpha ).

Version 6.3 corrects the following problems:

• The Standard Library vector class now allocates space correctly for elements greater than 1024 bytes; runtime core dumps caused by incorrect allocation in previous versions no longer occur. [10.1459]
• The iostreams and locales are now multi-thread safe. [10.1429]
• Compiling a program in -std strict_ansi mode using the basic_fstream class no longer causes run-time seg faults or core dumps. [10.1357]
• The basic_string::find_first_not_of(charT, size_type) function now works correctly if the string contained embedded nulls. [10.1316]
• The Version 6.2 string extraction operator no longer removes the extra space at the end of the string, as in the following example

  ifstream inFile("input.dat"); // input.dat contains "abc de" inFile >> word; // read "abc" inFile.get(ch1); // ch1 should be space, was 'd'

  [10.1300]

• Two of the basic_string::compare() member functions no longer throw an exception if the length of the second string is longer than the length of the current string. They no do so only if the position the user specifies within the second string is greater than the length of the second string. [10.1298]
• The prototype for the set_new_handler() is now included in the <new> header file when you specify -nostdnew on the command line.
• The basic_string::resize() member function now works correctly. If two strings point at the same underlying char* and the resize() function is called on one of them, you can change the underlying string for one of the strings without affecting the value of the other.
• You can now call the algorithm stable_sort() more than once with the same container without causing a seg fault.

Restrictions are as follows:

• When using the Standard Library iostreams for interactive input to cin from a terminal, a user may have to type more than one Ctrl D to indicate end-of-file. [10.1413]
• Currently you might encounter compilation errors if you try to use a user-defined allocator and pointer class with the STL containers. This problem will be fixed in a future release. [10.1430]

Enhancements, changes, and problems corrected are as follows:

• Fix for unexpected null cleanup block error
  When an exception was raised and caught in the catch clause at runtime, some loops with a try-catch block would generate an internal error about an unexpected null cleanup block. This error was caused by the runtime environment and has been corrected.
• Fix for raw_storage_iterator assignment operator
  In versions 6.2 and earlier, a problem in the assignment operator for the class raw_storage_iterator could cause a run-time seg fault if, for example, you called the algorithm stable_sort() more than once with the same container. The problem has been corrected. [10.1284]
• Fix for basic_string::compare() member functions
  In version 6.2, two of the basic_string::compare() member functions were throwing an exception if the length of the second string was longer than the length of the current string. This has been fixed so that they throw an exception only if the position the user specifies within the second string is greater than the length of the second string. [10.1287]
• Fix for basic_string::resize()
  A problem in the basic_string::resize() member function in Version 6.2 has been corrected. The incorrect behavior was that if two strings pointed at the same underlying char* , and the resize() function was called on one of them, and if you then changed the underlying value for one string, the value for the other string would also be changed. [10.1287]
• Fix to string assignment operator when assigning string with embedded nulls
  A problem in the basic_string assignment operator prevented strings containing embedded nulls from being copied correctly. The problem has been corrected. [10.1238]
• Fix for missing set_new_handler() prototype when specifying -nostdnew
  The prototype for the set_new_handler() function was missing from the <new> header file if you specified
  -nostdnew on the command line. The problem has been corrected.

The following enhancements and changes are included in Version 6.2:

• Cleaner header file inclusion policy
  This new version of the Standard Library is much cleaner in its inclusion of unnecessary headers. For example, the header file <algorithm> no longer includes <functional> . <ostream> and <istream> no longer include <locale> . Programs that used to count on these inclusions might break. You can correct them by explicitly including any header files you use in your own sources.
• New interface to get_temporary_buffer and use_facet
  Because the Version 6.2 C++ compiler now supports explicit template function arguments, it also supports the standard interface to the get_temporary_buffer() function. The following example shows how code must change:
  Change this:

  get_temporary_buffer(len,(T*)0); // two arguments

  
  to this:

  get_temporary_buffer<T>(len); // one argument

  
  where "T" is the value type of the container.
  The standard interface to the locale class use_facet() function is also now supported. The following example shows how code must change:
  Change this:

  use_facet(loc,(ctype<char>*)0);

  
  to this:

  // use_facet only takes one argument use_facet<ctype<char> >(loc);

• Many common iostream and locale instantiations (for example, those based on the char type) have been put into the Standard Library to improve compile-time performance. If you want to instantiate them yourself and use your own instantiations (perhaps to have a debugging version), follow these steps:
  1. Compile with the macro __FORCE_INSTANTIATIONS defined ( -D__FORCE_INSTANTIATIONS ).
  2. Link with the option -nopreinst . The linker then finds the instantiations in your repository before it finds those in the Standard Library.

The following problems are corrected in Version 6.2:

• money_get / money_put locale facets now conform to C++ International Standard
  The money_get and money_put locale facets have been corrected to match the standard. In the previous version, for example, money_get appeared as:

  template <class charT, bool Intl = false, class InputIterator = istreambuf_iterator<charT> > class money_get;

  
  They now correctly match the standard, where the interface appears as:

  template <class charT, class InputIterator = istreambuf_iterator<charT> > class money_get;

  
  Note that the second template argument "Intl" has been removed. The member functions get() and put() now accept Intl as an argument.

• ios_base::openmode flags set to conform to Standard
  The standard file stream classes have been corrected to conform to the Standard with regard to setting the ios_base::openmode flags. In the previous release, it was possible to create a file for reading and writing with this code:

  #define __USE_STD_IOSTREAM #include <stdlib.h> #include <fstream> int main() { fstream fs("foo.out", ios_base::in | ios_base::out); fs << "abc" << endl; return EXIT_SUCCESS; }

  
  In the current release, this code works only if the file already exists. If the file does not exist, you need to also specify ios_base::trunc ; that is, you must change the first line in main() to:

  fstream fs("foo.out", ios_base::in | ios_base::out | ios_base::trunc);

  
  This conforms to table 92 in the Standard, which specifies the "C" equivalent of the File open modes.

• Correction to list::sort(Compare)
  A bug in the list::sort(Compare comp) member function is corrected. Previously, if users supplied their own Comparison function object for the element of the list, the compiler issued a message stating that it required an operator< defined for the element type. This no longer occurs.
• reverse_iterator now matches the Standard
  reverse_iterator has been changed to match the standard. It now takes only one template argument of type iterator instead of five. Users must change existing code to remove the additional unnecessary arguments.
• bitset constructors no longer accept a const char
• A bitset can no longer be constructed with a const char* argument. For example, the following no longer compiles:

  bitset<32> b("111111111");

  
  The constructor that takes a string is a templatized constructor, and thus can perform type deductions only on exact matches, not conversions (for example, const char* to string). To make the code in the previous example compile with the current version, the argument must be explicitly cast to a string, as follows:

  bitset<32> b( string("111111111"));

• assign(size_t) removed from vector , deque , list
  Previous releases of the Standard Library contained a member function called assign() inside the vector , deque , and list classes. This function accepted only a size_t argument. This has been removed, because it is not in the Standard. You must add an extra argument indicating the value you want assigned. For example, you change calls like the following:

  v.assign(5); // where v is a vector<int>

  
  to:

  v.assign(5, int());

• allocator<>::deallocate(pointer) removed
  The member function allocator<>::deallocate(pointer) has been removed. The Standard requires two arguments for this member function. The second argument should be of size_type and have the same value as the first argument passed to allocator<>::allocate() .
• basic_ios now initializes skipws|dec
  To conform to the Standard, the following basic_ios constructor constructs a basic_ios object and initializes the format control bits to skipws | dec :

  explicit basic_ios(basic_streambuf<charT, traits>*sb)

  
  Previously ,this constructor also initialized the bit indicating that output is right justified. Because the constructor is called while constructing any of the IOStream objects cout , clog , cerr , wcout , wclog , or wcerr , the difference is apparent if you examine the format control bits set after initializing one of these objects.
  Consider the following program:

  #include <stdlib.h> #include <iostream> using namespace std; int main() { cout << cout.flags() << endl; cout << clog.flags() << endl; cout << cerr.flags() << endl; cout << wcout.flags() << endl; cout << wclog.flags() << endl; cout << wcerr.flags() << endl; return EXIT_SUCCESS; }

  
  The output now indicates that only the skipws and dec format control bits are initialized. Previously it would have indicated that the right bit was also set.

• Some iterator classes removed
  The following classes no longer exist in the Standard and have been removed from library headers.

  reverse_bidirectional_iterator
  random_access_iterator
  bidirectional_iterator
  forward_iterator
  output_iterator
  input_iterator

  
  Use instead the template class iterator with the template argument category to indicate which type of iterator you are constructing.
• The default allocator argument changed for basic_string
  The default allocator argument for the class basic_string has been changed from allocator<void> to allocator<charT> . Any STL container constructed with an allocator<void> template argument no longer compiles, because the specialization of allocator<void> does not contain all the necessary typedefs.
• strstream now deletes underlying strstreambuf
  A problem has been corrected in the Standard Library strstream classes that prevented underlying strstreambuf (and thus the string) from being deleted when the strstream object was destroyed. The standard states that they should be deleted if strmode & allocated is true and strmode & frozen is not true.
  For example:

  #define __USE_STD_IOSTREAM #include <strstream> void func() { ostrstream myostr; myostr << "abc"; }

  
  If you called func() the string "abc" was never deleted when the myostr stream was destroyed. This problem has been corrected. Note that the Class Library strstream classes have always deleted the underlying string.

• sync_with_stdio() function is static
  In previous versions, the function sync_with_stdio() was incorrectly declared as a member function of ios_base . The function is now correctly defined as a static member function; it is no longer necessary to call it with the "->" or or "." notation.

This section describes problems you might encounter when using the current release of the C++ Standard Library with the Compaq C++ compiler. Where appropriate, workarounds are suggested.

• Do Not Use Standard Library template Definition File Names
  The Standard Library supplies the following template definition files in /usr/include/cxx :

  algorithm.cc	fstream.cc	streambuf.cc	vector.cc	time.cc
  bitset.cc	ios.cc	locimpl.cc	string.cc	ctype.cc
  istream.cc	numbrw.cc	tree.cc	collate.cc	messages.cc
  complex.cc	iterator.cc	ostream.cc	valarray.cc	money.cc
  deque.cc	list.cc	sstream.cc	valimp.cc	numeral.cc
  rwlocale.cc

  
  If you use the same prefix name for any of your local files and have the directory that contains them in your include search path before /usr/include/cxx , the automatic instantiation mechanism picks up your local copy and does not correctly find the library files. (See Using Compaq C++ for Tru64 UNIX and Linux Alpha for more information about how the prelinker finds template definition files.)
  Do not use any of these names as source file names for your application.
• Redeclaration of Standard Library Functions
  Many of the prototypes in the Standard Library have been changed to conform to the C++ International standard by the addition of exception specifications. This means that if you have redeclared the declarations in your own code, you need to add the correct exception specification in order to match what's declared in the header.
  For example:

  #include <new.h> // override default operator new // this gives an error inline void* operator new(size_t s);

  
  To prevent this, you'd need to change your new() declaration to:

  inline void* operator new(size_t s) throw(std::bad_alloc);

• Files/Macros for Internal Use Only
  Compaq C++ Version 6.1 ships the following non-Standard headers which are for internal use only. Their contents are subject to change and can not be relied upon.

  <stdcomp>	<stl_macros>	<stddefs>	<compnent.hxx>
  <stdmutex>	<stdexcept>	<lochelp>	<locimpl>
  <locimpl.cc>	<valimp>	<valimp.cc>	<vendor>
  <codecvt>	<codecvt.cc>	<collate>	<collate.cc>
  <ctype>	<ctype.cc>	<locvector>	<math>
  <messages>	<messages.cc>	<money>	<money.cc>
  <numeral>	<numeral.cc>	<random>	<rwcats>
  <rwdispatch>	<rwlocale>	<rwlocale.cc>	<rwstderr>
  <rwstderr_macros>	<string_ref>	<time>	<time.cc>
  <traits>	<usefacet>

  
  In addition both Standard and non-Standard headers make use of macros beginning with _RW or __RW . These _RW* and __RW* macros are for internal use only. They are subject to change and can not be relied on.
• The size of long double has changed in Compaq Tru64 UNIX Version 5.0. If you are using the standard iostreams or locale library for inputting or outputting long doubles, you must specify -nopreinst on your link line to obtain instantiations that work correctly.
• Use of exception in <math.h> and Standard C++ Library
  In Compaq C++ Version 6.1, namespaces resolve a conflict between the name exception found in the header <math.h> , which represents a structure, and the name exception found in the C++ Standard Library header <exception> , which represents the Standard Library exception class. The structure exception from <math.h> is visible in the global namespace. The Standard Library exception class from <exception> is visible in the std namespace.
  Because of this behavior, if you include, directly or indirectly, both of the headers <math.h> and <exception> you must qualify actual uses of exception to avoid name conflicts:

  #include <math.h> #include <exception> int main () { ::exception e; // exception from math.h std::exception e1; // Standard Library exception class return 0; }

• collate_byname<wchar_t>::do_transform()
  The function collate_byname<wchar_t>::do_transform() seg faults if you use it with any locale other than the "C" locale. This happens because of a bug with the underlying C function wcsxfrm() . No workaround currently exists for this problem.
• ctype_base::graph
  In the current implementation of the ctype_base class, a character has a graph property if and only if it also has an alpha , a digit or a punct property. Thus, mathematical and scientific symbols and dingbats from the UNICODE character set will not be classified properly.
• IOStreams cannot output IEEE NaNs/Infinities
  The Standard IOStreams Library does not support output for IEEE NaNs and Infinities.
• ios_base::out does not truncate a file to zero length
  The ios_base::openmode ios_base::out should open a file for output. This means that the file is either truncated to zero length if it exists or created for writing if it does not. Therefore ios_base::out is the same as ios_base::out | ios_base_trunc .
  With our sources, the following program behaves incorrectly.

  #include <stdlib.h> #include <iostream> #include <fstream> using namespace std; int main() { fstream fs ("t.in",ios_base::out); fs << "A"; return EXIT_SUCCESS; }

  
  Where t.in contains xyz.
  After running this program, t.in contains

  Ayz

  
  It should contain

  A

  
  You can work around this problem by replacing ios_base::out with ios_base::out | ios_base::trunc .

• Overriding operator new in library
  You can define a global operator new() to displace the version used by the C++ Standard Library or C++ Class Library. For instructions, see Overriding operator(new) in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• The -define_templates and -tall options are not guaranteed to work with the Standard Library. Use automatic instantiation or specify -tused instead.
  When compiled with -define_templates or -tall , the following code generates compilation errors indicating that no operator "<" (and ">" or "+" or "-") matches these operands:

  #include <map> map<int,int> foo;

  
  The instantiation options are not guaranteed to work with the Standard Library because they request the compiler to instantiate all templates, even those that are not used.
  The -tall option does not work because rb_tree , the underlying implementation of map and set supports a bidirectional iterator class. Thus, operator+ , operator- , operator< and operator> are not defined in the iterator for that class.
  When you instantiate the tree with cxx -tall or cxx -define_templates , the compiler attempts to instantiate recursively everything that is typedef ed, even if not used. Thus, the tree contains a typedef for std::reverse_iterator<iterator> , which then instantiates the global class reverse_iterator with the tree iterator as the template argument RandomAccessIterator , a misnomer in this case.
  This behavior generates undefined symbols for these operators because they are used within the definition of the operator member functions inside reverse_iterator . The compiler therefore attempts to instantiate them even though they do not exist.
  Specifying -tused for the Standard Library directs the compiler to only instantiate those templates that are used.

• Description of the initial state of the stringstream ctor
  There has been some controversy in the comp.lang.c++ reflector and within the standards committee on the semantics of the stringstream constructor. Consider the following example:

  #define __USE_STD_IOSTREAM #include <stdlib.h> #include <sstream> int main() { ostringstream ost("Hello, "); // ost.rdbuf()->pubseekoff(0,ios::end,ios::out); ost << "world!"; cout << ost.str() << endl; return EXIT_SUCCESS; }

  
  Depending on the setting of the streambuf put pointer after the initial construction, the program could print either "Hello, world!" or "world!". The Rogue Wave (and Compaq C++) interpretation is that the stringstream constructor does not change the initial position of the streambuf pointer, so that the program prints "world!".
  If you want to change the setting of the put pointer to match the other interpretation (that the pointer should move to the end of the initializer string), you must insert a call to pubseekoff() , as shown in the commented line.
  If the ANSI C++ committee issues a clarification on this matter Compaq C++ will implement their decision.

• Linker might produce multiply defined symbols from Standard Library
  The linker might produce multiply defined symbols from the Standard Library when linking against your own shared library or libraries. If you find multiply defined symbols like the following coming from libcxxstd.a , you might be creating one or more shared libraries and then using those shared libraries to create an executable.

  ld: /usr/lib/libcxxstd.a(typeinfo.o): std::__vtbl_3std9type_info: multiply defined /usr/lib/libcxxstd.a(vec_newdel.o): __vec_new_eh: multiply defined

  
  The problem is that libcxxstd.a is an archive library. When you create a shared object that references this library, the symbols are pulled into that shared object. When you then use the shared library, it finds the symbol both in your shared object and in the libcxxstd.a library archive. To work around this problem, follow these steps:

  1. If you are creating multiple shared libraries, create them without linking in the libcxxstd library and with the expect_unresolved ld flag to prevent linker errors. For example:

     cxx -shared -nocxxstd -expect_unresolved "*std*" -o libA.so obj1.o cxx -shared -nocxxstd -expect_unresolved "*std*" -o libB.so obj2.o . . .

  2. Link the final executable normally, so that unresolved symbols from libcxxstd are linked in. For example:

     cxx -L. main.cxx -lA -lB

  
  A release of libcxxstd as a shared library is planned once once the library interface is stablilized.
• Compilation warnings and errors with auto_ptr
  Using the auto_ptr class for conversion can generate compilation warnings; for example:

  #include <stdlib.h> #include <memory> #include <iostream> class Base {}; class Derived: public Base {}; std::auto_ptr<Derived> f(); int main() { // warning: see issue 84 on the C++ Standards Committee //language issues list at //http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/core-issues.htm std::auto_ptr<Base> q = f(); return EXIT_SUCCESS; }

  
  Currently there is no consensus in the ANSI committee about whether these errors are caused by a bad design of the auto_ptr class or are compiler bugs. We hope to have a resolution soon. In the meantime, the workaround is to use a pragma or compiler option to disable the warning.
  Remember that auto_ptr s should not be used as elements of an STL container, because they do not meet the CopyConstructible and Assignable requirements for Standard Library container elements.

The following enhancement is included in Version 6.1-029:

• Smaller executables for users of the basic_string library component
  The Standard Library now provides a better separation of the STL and Standard IO components. As a result, users of the basic_string component of the Standard Library should obtain smaller executables. In Version 6.1, using only a string in an application caused all iostream and locale object files from the Standard Library to be included in the executable. These unnecessary files are no longer included.

The following problems are corrected in Version 6.1-029:

• list::sort (Compare comp) member function now correct
  Previously, if users supplied their own Comparison function object for the element of the list, the compiler still required an operator< defined for the element type. This is no longer the case.
• strstream now correctly deletes underlying strstreambuf
  The Standard Library strstream classes now delete the underlying strstreambuf (and string ) when a strstream object is destroyed. The standard states that they should be deleted if strmode & allocated is true and strmode & frozen is not true.
  For example:

  #define __USE_STD_IOSTREAM #include <strstream> void func() { ostrstream myostr; myostr << "abc"; }

  
  If you called func() the string "abc" was never deleted when the myostr stream was destroyed. This problem has been corrected. Note that the Class Library strstream classes have always deleted the underlying string.

• stringstream.str() can now be accessed after seekp(0)
  The underlying string in a stringstream can now be accessed properly after a seekp(0) . For example, the following program no longer causes a run-time core dump.

  #include <iostream> #include <sstream> int main() { std::ostringstream out; out << std::string("This is a test"); out.seekp(0); std::cout << "out.str(): " << out.str() << std::endl; return EXIT_SUCCESS; }

• <wchar.h> can be included before <fstream>
  Including <wchar.h> before <fstream> no longer causes compilation errors.
• std::ostrstream::freeze() no longer leaks memory
  The std::ostrstream::freeze() function no longer leaks memory when used in combination with an o strstram object. If you declare an ostrstream object as std::ostrstream out, the memory to which output is written is dynamically allocated. Previously, calling freeze(false) incorrectly froze a stream, thereby preventing the deletion of allocated memory. This is no longer the case.
  The following program (which would have illustrated the memory leak when instrumented with third degree) no longer leaks memory.

  #include <stdlib.h> #ifndef __USE_STD_IOSTREAM #define __USE_STD_IOSTREAM #endif #include <iostream> #include <strstream> void TestIt() { std::ostrstream out; out << std::string("This is a test"); out.freeze(false); char *s = out.str(); return; } int main() { for (int i = 0; i < 100; i++) TestIt(); return EXIT_SUCCESS; }

• Math overloads in <valarray> OK
  Including <valarray> and then calling some of the math routines (for example, abs() ) with an int argument might have produced an ambiguity error. This has been corrected.

The C++ Standard Library provided with this release defines a complete specification (with some differences) of the C++ International Standard. The library includes the ANSI locale and iostream libraries. Reference pages describing the Standard Library are provided; you can type man cxxlibstd_intro to access them.

Tutorial programs illustrating functionality found in the Standard Library, including the locale , iostream , and STL classes shipped with this release are available in:

/usr/examples/cxx/*.cxx

You can compile and run these programs and use them as models for your own coding. The expected output for each program can be found in:

/usr/examples/cxx/*.res

Version 6.1 introduces the following major enhancements and changes. For detailed information, on the Compaq C++ Standard Library, refer to Using Compaq C++ for Tru64 UNIX and Linux Alpha.

• Support for C++ International Standard iostream and locale
  The Version 6.1 kit contains detailed documentation in PostScript and PDF formats:

  /usr/share/doclib/cplusplus/intzln.ps
  /usr/share/doclib/cplusplus/intzln.pdf
  /usr/share/doclib/cplusplus/locale.ps
  /usr/share/doclib/cplusplus/locale.pdf

• Reference pages for the Standard Library. You can access them by typing man cxxlibstd_intro .
• Several new options (see The C++ Standard Library in Using Compaq C++ for Tru64 UNIX and Linux Alpha .)
• pre-ANSI/ANSI iostreams compatibility.
• Support for ANSI/pre-ANSI operator new() .
• Support for global array new and delete .

Additional changes include the following:

• Support for long long and unsigned long long types.
  The non-ANSI standard types long long and unsigned long long are now supported in the Standard Library iostreams as well as being valid types for numeric_limits specializations and as types for which destroy() specializations are provided. For example, you can now say:

  long long l; cout << l << endl; // compiles without error

  
  Note that these types are not supported under -std strict_ansi or -std strict_ansi_errors compiler mode.
  long long and unsigned long long are also supported in the iostream class library in the default compiler mode.

• Common instantiation libraries no longer needed
  Because Version 6.n uses compile time rather than link time template instantiation, there is no use for common instantiation libraries. No build_common_instantiation_library script is supplied. See Using Templates in Using Compaq C++ for Tru64 UNIX and Linux Alpha .
• Interface change for STL distance() function
  Because the Version 6.1 compiler now supports partial specialization of class templates, the interface to the distance() algorithm has been updated to conform to the latest C++ standard. This means that previously, if you made a call to distance , the result was returned by using a reference argument for the third argument:

  // pre 6.1 the result was returned in d distance(first,last,d);

  
  Beginning with V6.1, the result is returned in the return type:

  d = distance(first,last); // 6.1

  
  You must therefore change all your calls to distance() .

• Specific changes to match the November C++ International Standard:
  • iterator_traits::distance_type now iterator_traits::difference_type
    The name of the typedef inside the classes iterator_traits and iterator that specifies the type of the result when two iterators are subtracted has been changed from distance_type to difference_type .
  • typedef name changes in iterator classes
    The names of some of the typedefs in the reverse_iterator and reverse_bidirectional_iterator classes have changed as follows:

    iter_type is now iterator_type
    reference_type is now reference
    pointer_type is now pointer
    distance_type is now difference_type

  • slice/gslice classes member function length() name change
    The member function length() in the slice and gslice classes has changed its name to size() .
  • has_denorm data member of the numeric_limits class changed The has_denorm data member of the numeric_limits class, <limits> , has been updated. has_denorm is changed from type bool to an enum type, float_denorm_style , to reflect that support for denormalized values might not be detectable at compile time. The float_denorm_style type looks like this:

    namespace std { enum float_denorm_style { denorm_indeterminate = -1; denorm_absent = 0; denorm_present = 1; }; }

    
    The values representing the presence or absence of denorms are as follows:

    denorm_indeterminate: cannot determine if type supports denormalized at compile time denorm_absent: the type does not support denormalized values denorm_present: the type supports denormalized values

  • Default allocator value for map and multimap has changed
    The default value for the template argument Allocator in map and multimap has changed from allocator<T> to allocator<pair<const Key, T> > .
• Some Standard Library ambiguities corrected
  The Standard Library vector, deque and list containers no longer generate ambiguities when using their constructors or insert member functions. However, if you declare a basic_string of int , you might encounter ambiguities in the constructors, append , assign , insert , and replace member functions. For example if you write:

  #include <stdlib.h> #include <string> int main() { basic_string<int> si (5,0); return EXIT_SUCCESS; }

  
  A compilation error results from the overload resolution between integral and iterator types. The constructors involved are:

  // construct n elements and initialize with value basic_string(size_type n, charT c, const Allocator& a = Allocator()); // construct a vector using iterator ranges template<class InputIterator> basic_string(InputIterator begin, InputIterator end, const Allocator& a = Allocator());

  
  The compiler matches on the constructor basic_string(InputIterator begin, InputIterator end, ...) The reason is that size_type a size_t is an unsigned long on Compaq C++. So you have:

  basic_string(unsigned long, int, ...) vs. basic_string(int, int,...)

  
  The second constructor is the better match, but it is not what we want, because we are not constructing with iterator ranges.
  The workaround is to avoid matching on iterator types by casting integral arguments. So for example, the previous program would compile correctly if the size argument were cast to a (size_t) :

  #include <stdlib.h> #include <string> int main() { basic_string<int> si ((size_t)5,0); return EXIT_SUCCESS; }

This section describes library problems corrected in Version 6.1.

• STL map containers are now accessible in multithreaded environments
  Erasing elements from two STL map containers in a multithreaded environment no longer causes a segmentation fault. With previous versions, the problem was caused by an incorrect locking mechanism in an implementation class used when a map is being "erased".
  To correct the original problem reported against the STL map class, we reworked map's entire underlying implementation class. The underlying implementation class is found in the <tree> header. This class has been modified so that it no longer contains static data members.
• Standard Library IOStream cerr.flush() no longer hangs in multithreaded environments
  Applications making use of the Standard Library IOStream cerr.flush() function in combination with other I/O related activities in a multithreaded environment no longer experience hangs in their executing code.
• Piping standard output or standard error to a file no longer loses output when using Standard Library IOStreams
  The symptoms of this Standard Library bug varied. One noticeable effect could be seen when executing a program using Standard Library IOStreams which inserted items to cout and then piped this output along with other output to a file.
  For example, if a program inserted into cout as follows:

  #define __USE_STD_IOSTREAM #include <stdlib.h> #include <iostream> int main() { cout << "Hello from C++" << endl; return EXIT_SUCCESS }

  
  And if a script, d.sh executed the above program and made use of a command that output to Standard Error like this:

  a.out ls -X

  
  And if you piped both Standard Output and Standard Error to a file like this:

  d.sh >& testlog

  
  The output to Standard Output was lost. The testlog would contain:

  + ls -X ls: illegal option -- X usage: ls [ -1ACFLRabcdfgilmnopqrstux ] [files]

  
  Rather than:

  Hello from C++ + ls -X ls: illegal option -- X usage: ls [ -1ACFLRabcdfgilmnopqrstux ] [files]

  
  This problem has been corrected.

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