add -std=c++98 to compiler

Author: WalterBright

changelog/cpp98.dd

@@ -0,0 +1,64 @@
+Ddoc
+
+$(H2 Transition to C++11 character types)
+
+        With C++11 comes the advent of changed character type mangling.
+        D's default behavior is now to conform to this. However, this
+        will break existing code. Therefore, the old behavior can be
+        retained by using the -std=c++98 compiler switch. This
+        will also set the predefined version Cpp98.
+        For Win32 compilations using Digital Mars C++, version Cpp98 will
+        be predefined.
+
+        Of particular note is the new difference between wchar and wchar_t on
+        Windows. This will manifest itself as compile errors when
+        interfacing wchar* with wchar_t* code when calling the Windows API.
+        A cast will resolve the issue.
+
+        Going forward we recommend using WCHAR instead of wchar or wchar_t
+        when interfacing to Windows API functions. (WCHAR is Microsoft
+        Windows' 16 bit character type.)
+
+$(H3 C++ Type Equivalence)
+
+$(H4 Cpp98 behavior:)
+
+$(TABLE
+$(THEAD D       , Posix           , DMC++ Windows   , VC++ Windows)
+
+$(TROW  wchar   , unsigned short  , wchar_t         , wchar_t)
+$(TROW  dchar   , wchar_t         , unsigned        , unsigned)
+$(TROW  wchar_t , wchar_t         , wchar_t         , wchar_t)
+$(TROW  WCHAR   , --              , wchar_t         , wchar_t))
+
+$(H4 New behavior:)
+
+$(TABLE
+$(THEAD D       , Posix           , DMC++ Windows   , VC++ Windows)
+
+$(TROW  wchar   , char16_t        , wchar_t         , char16_t)
+$(TROW  dchar   , char32_t        , unsigned        , char32_t)
+$(TROW  wchar_t , wchar_t         , wchar           , wchar_t)
+$(TROW  WCHAR   , --              , wchar           , wchar_t))
+
+
+$(H3 Name Mangling:)
+
+$(H4 Cpp98 behavior:)
+
+$(TABLE
+$(THEAD D       , Posix   , DMC++ Windows   , VC++ Windows)
+
+$(TROW  wchar   , t       , _Y              , _W)
+$(TROW  dchar   , w       , I               , I)
+$(TROW  wchar_t , w       , _Y              , _W))
+
+$(H4 New behavior:)
+
+$(TABLE
+$(THEAD D       , Posix   , DMC++ Windows   , VC++ Windows)
+
+$(TROW  wchar   , Ds      , _Y              , _S)
+$(TROW  dchar   , Di      , I               , _U)
+$(TROW  wchar_t , w       , _Y              , _W))
+

src/dmd/cli.d

@@ -561,6 +561,14 @@ dmd -cov -unittest myprog.d
             `$(UNIX Generate shared library)
              $(WINDOWS Generate DLL library)`,
         ),
+        Option("std=<standard>",
+            "set compatiblity with <standard>",
+            "Standards supported are:
+            $(UL
+             $(LI $(I c++98): Use older C++98 name mangling,
+                  Predefines `Cpp98` $(LINK2 $(ROOT_DIR)spec/version.html#predefined-versions, version))
+            )",
+        ),
         Option("transition=<id>",
             "help with language change identified by 'id'",
             `Show additional info about language change identified by $(I id)`,

src/dmd/cond.d

@@ -664,6 +664,7 @@ extern (C++) final class VersionCondition : DVCondition
             case "CppRuntime_Gcc":
             case "CppRuntime_Microsoft":
             case "CppRuntime_Sun":
+            case "Cpp98":
             case "unittest":
             case "assert":
             case "all":

src/dmd/globals.d

@@ -148,12 +148,14 @@ struct Param
     bool fix16997;          // fix integral promotions for unary + - ~ operators
                             // https://issues.dlang.org/show_bug.cgi?id=16997
     bool fixAliasThis;      // if the current scope has an alias this, check it before searching upper scopes
+
     /** The --transition=safe switch should only be used to show code with
      * silent semantics changes related to @safe improvements.  It should not be
      * used to hide a feature that will have to go through deprecate-then-error
      * before becoming default.
      */
     bool vsafe;             // use enhanced @safe checking
+    bool cpp98;             // follow C++98 type system issues rather than C++11
     bool ehnogc;            // use @nogc exception handling
     bool dtorFields;        // destruct fields of partially constructed objects
                             // https://issues.dlang.org/show_bug.cgi?id=14246

src/dmd/globals.h

@@ -123,7 +123,8 @@ struct Param
     bool fix16997;      // fix integral promotions for unary + - ~ operators
                         // https://issues.dlang.org/show_bug.cgi?id=16997
     bool vsafe;         // use enhanced @safe checking
-    bool ehnogc;        // use @nogc exception handling
+    bool cpp98;             // follow C++98 type system issues rather than C++11
+    bool ehnogc;            // use @nogc exception handling
     bool dtorFields;        // destruct fields of partially constructed objects
                             // https://issues.dlang.org/show_bug.cgi?id=14246
     bool showGaggedErrors;  // print gagged errors anyway

src/dmd/mars.d

@@ -1122,6 +1122,9 @@ void addDefaultVersionIdentifiers(const ref Param params)
     VersionCondition.addPredefinedGlobalIdent("D_Version2");
     VersionCondition.addPredefinedGlobalIdent("all");
 
+    if (params.cpp98)
+        VersionCondition.addPredefinedGlobalIdent("Cpp98");
+
     if (params.cpu >= CPU.sse2)
     {
         VersionCondition.addPredefinedGlobalIdent("D_SIMD");
@@ -2054,6 +2057,10 @@ bool parseCommandLine(const ref Strings arguments, const size_t argc, ref Param
             params.manual = true;
             return false;
         }
+        else if (arg == "-std=c++98")        // https://dlang.org/dmd.html#switch-std
+        {
+            params.cpp98 = true;
+        }
         else if (arg == "-run")              // https://dlang.org/dmd.html#switch-run
         {
             params.run = true;
@@ -2190,6 +2197,14 @@ private void reconcileCommands(ref Param params, size_t numSrcFiles)
         params.useExceptions = false;
     }
 
+    /* TEMPORARILY set this to true until the runtime library is updated,
+     * in order to not leave the system in an unbuildable state.
+     */
+    params.cpp98 = true;
+
+    if (params.isWindows && !params.mscoff)
+        params.cpp98 = true;             // DMC++ is a C++98 compiler
+
 
     if (!params.obj || params.lib)
         params.link = false;

test/fail_compilation/reserved_version.d

@@ -105,6 +105,7 @@ fail_compilation/reserved_version.d(206): Error: version identifier `CppRuntime_
 fail_compilation/reserved_version.d(207): Error: version identifier `CppRuntime_Gcc` is reserved and cannot be set
 fail_compilation/reserved_version.d(208): Error: version identifier `CppRuntime_Microsoft` is reserved and cannot be set
 fail_compilation/reserved_version.d(209): Error: version identifier `CppRuntime_Sun` is reserved and cannot be set
+fail_compilation/reserved_version.d(210): Error: version identifier `Cpp98` is reserved and cannot be set
 ---
 */
 
@@ -216,6 +217,7 @@ version = CppRuntime_DigitalMars;
 version = CppRuntime_Gcc;
 version = CppRuntime_Microsoft;
 version = CppRuntime_Sun;
+version = Cpp98;
 
 // This should work though
 debug = DigitalMars;
@@ -300,6 +302,7 @@ debug = CppRuntime_DigitalMars;
 debug = CppRuntime_Gcc;
 debug = CppRuntime_Microsoft;
 debug = CppRuntime_Sun;
+debug = Cpp98;
 debug = D_Coverage;
 debug = D_Ddoc;
 debug = D_InlineAsm_X86;

test/fail_compilation/reserved_version_switch.d

@@ -82,6 +82,7 @@
 // REQUIRED_ARGS: -version=CppRuntime_Gcc
 // REQUIRED_ARGS: -version=CppRuntime_Microsoft
 // REQUIRED_ARGS: -version=CppRuntime_Sun
+// REQUIRED_ARGS: -version=Cpp98
 // REQUIRED_ARGS: -version=D_Coverage
 // REQUIRED_ARGS: -version=D_Ddoc
 // REQUIRED_ARGS: -version=D_InlineAsm_X86
@@ -178,6 +179,7 @@
 // REQUIRED_ARGS: -debug=CppRuntime_Gcc
 // REQUIRED_ARGS: -debug=CppRuntime_Microsoft
 // REQUIRED_ARGS: -debug=CppRuntime_Sun
+// REQUIRED_ARGS: -debug=Cpp98
 // REQUIRED_ARGS: -debug=D_Coverage
 // REQUIRED_ARGS: -debug=D_Ddoc
 // REQUIRED_ARGS: -debug=D_InlineAsm_X86
@@ -279,6 +281,7 @@ Error: version identifier `CppRuntime_DigitalMars` is reserved and cannot be set
 Error: version identifier `CppRuntime_Gcc` is reserved and cannot be set
 Error: version identifier `CppRuntime_Microsoft` is reserved and cannot be set
 Error: version identifier `CppRuntime_Sun` is reserved and cannot be set
+Error: version identifier `Cpp98` is reserved and cannot be set
 Error: version identifier `D_Coverage` is reserved and cannot be set
 Error: version identifier `D_Ddoc` is reserved and cannot be set
 Error: version identifier `D_InlineAsm_X86` is reserved and cannot be set