From c821b7cbd5b3b10bc1a0d7b9e79121e927528b70 Mon Sep 17 00:00:00 2001 From: Jens Maurer Date: Thu, 1 Feb 2001 22:28:23 +0000 Subject: [PATCH] Portability hints for MSVC [SVN r8847] --- microsoft_vcpp.html | 251 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 251 insertions(+) create mode 100644 microsoft_vcpp.html diff --git a/microsoft_vcpp.html b/microsoft_vcpp.html new file mode 100644 index 0000000..8618eba --- /dev/null +++ b/microsoft_vcpp.html @@ -0,0 +1,251 @@ + + + +Portability Hints: Microsoft Visual C++ 6.0 SP4 + + + + + + + + + + + + + +
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+ +

+ +

Portability Hints: Microsoft Visual C++ 6.0 SP4

+ +Similar to the +portability hints for Borland C++, +this page provides hints on some language features of the Microsoft Visual C++ +version 6.0 servicepack 4 compiler. + +Each entry in the following list describes a particular issue, +complete with sample source code to demonstrate the effect. +Most sample code herein has been verified to compile with gcc 2.95.2 +and Comeau C++ 4.2.44. + + +

Preprocessor symbol

+ +The preprocessor symbol _MSC_VER is defined for all +Microsoft C++ compilers. Its value is the internal version number of the +compiler interpreted as a decimal number. Since a few other compilers +also define this symbol, boost provides the symbol +BOOST_MSVC defined in +boost/config.hpp +to the value of _MSC_VER if and only if the compiler is really +Microsoft Visual C++. + +The following table lists some known values. +

+ + + + + + + + + + + + +
CompilerBOOST_MSVC value
Microsoft Visual C++ 6.0 SP41200
+ + +

Core Language

+ +

[chained using] Chaining using-declarations

+ +Chaining using-declarations do not work. +
+void f();
+
+namespace N {
+  using ::f;
+}
+
+void g()
+{
+  using N::f;  // C2873: 'f': the symbol cannot be used in a using-declaration
+}
+
+ + +

[explicit-instantiation] Explicit function template +instantiation

+ +Trying to explicitly instantiate a function template leads to the +wrong function being called silently. + +
+#include <stdio.h>
+
+template<class T>
+void f()
+{
+  printf("%d\n", sizeof(T));
+}
+
+int main()
+{
+  f<double>();      // output: "1"
+  f<char>();        // output: "1"
+  return 0;
+}
+
+ + +

[for-scoping] Scopes of definitions in for-loops

+ +The scope of variable definitions in for loops should be +local to the loop's body, but it is instead local to the enclosing +block: + + +
+int main()
+{
+  for(int i = 0; i < 5; ++i)
+   ;
+  for(int i = 0; i < 5; ++i)  // C2374: 'i': Redefinition; multiple initialization
+   ;
+  return 0;
+}
+
+ +Workaround: Enclose the offending for +loops in another pair of curly braces. + + +

[inclass-member-init] In-class member initialization

+ +In-class member initialization, require to implement a +Standard-conforming std::numeric_limits template, does +not work. + +
+struct A
+{
+  static const int i = 5;      // "invalid syntax for pure virtual method"
+};
+
+ + +

[koenig-lookup] Argument-dependent lookup

+ +Argument-dependent lookup, also called Koenig lookup, does not work. +No additional namespace induced from the argument types seem to be +considered. + +
+namespace N {
+  struct A {};
+  void f(A);
+}
+
+void g()
+{
+  N::A a;
+  f(a);     // 'f': undeclared identifier
+}
+
+ + +

[template-friend] Templates as friends

+ +A Template cannot be declared a friend of a class. + +
+template<class T>
+struct A {};
+
+struct B
+{
+  template<class T>
+  friend struct A;     // "syntax error"
+};
+
+ + +

[member-template-outofline] Out-of-line definitions of member +templates

+ +Defining member templates outside their enclosing class does not work. + +
+template<class T>
+struct A
+{
+  template<class U>
+  void f();
+};
+
+template<class T>
+template<class U>   // "syntax error"
+void A<T>::f()      // "T: undeclared identifier"
+{
+}
+
+ +Workaround: Define member templates in-line within +their enclosing class. + + +

[partial-spec] Partial specialization

+ +Partial specialization of class templates does not work. + +
+template<class T>
+struct A {};
+
+template<class T>
+struct B {};
+
+template<class T>
+struct A<B<T> > {};  // template class was already defined as a non-template
+
+ +Workaround: In some situations where interface +does not matter, member class templates can simulate partial +specialization. + + +

[template-value] Dependent emplate value parameters

+ +Template value parameters whose type depends on a previous template +parameter provoke an internal compiler error if the correct syntax +(with "typename") is used. + +
+template<class T, typename T::result_type> // C1001: INTERNAL COMPILER ERROR: ms
+c1.cpp, line 1794
+struct B {};
+ // (omit "typename" and it compiles)
+
+
+ + +

[wchar_t] wchar_t is not built-in

+ +The type wchar_t is not a built-in type. + +
+wchar_t x;  // "missing storage class or type identifier"
+
+ + +

+

+ +2001-02-01 Jens Maurer + +