PR c++/5287, PR c++/7910, PR c++/11021

	PR c++/5287, PR c++/7910,  PR c++/11021
	* config/i386/winnt.c (ix86_handle_dll_attribute): Don't add
	dllimport attribute if function is defined at declaration, but
	report error instead. Likewise for dllimport'd variable
	definitions.  Set implicit TREE_PUBLIC for dllimport'd variables
	declared within functions, Report error if dllimport or dllexport
	symbol is not global.
	(i386_pe_dllimport_p): Ignore dllimport attribute of functions
	if defined after declaration or if inlined. Don't allow definition
	of static data members of C++ classes. Don't dllimport virtual
	methods.
	(i386_pe_mark_dllexport): Warn about inconsistent dll attributes.
	(i386_pe_mark_dllimport): Remove unnecessary checks.
	(i386_pe_encode_section_info): Warn if the dllimport attribute
	and symbol prefix have been instantiated and then overridden.

	* doc/extend.texi: Document dllimport and dllexport attributes.

	* config/i386/winnt.c (i386_pe_output_labelref): Fix indents.

From-SVN: r68916

gcc/ChangeLog

+2003-07-04  Danny Smith  <dannysmith@users.sourceforge.net>
+
+	PR c++/5287, PR c++/7910, PR c++/11021
+	* config/i386/winnt.c (ix86_handle_dll_attribute): Don't add
+	dllimport attribute if function is defined at declaration, but
+	report error instead. Likewise for dllimport'd variable
+	definitions.  Set implicit TREE_PUBLIC for dllimport'd variables
+	declared within functions, Report error if dllimport or dllexport
+	symbol is not global.
+	(i386_pe_dllimport_p): Ignore dllimport attribute of functions
+	if defined after declaration or if inlined. Don't allow definition
+	of static data members of C++ classes. Don't dllimport virtual
+	methods.
+	(i386_pe_mark_dllexport): Warn about inconsistent dll attributes.
+	(i386_pe_mark_dllimport): Remove unnecessary checks.
+	(i386_pe_encode_section_info): Warn if the dllimport attribute
+	and symbol prefix have been instantiated and then overridden.
+
+	* doc/extend.texi: Document dllimport and dllexport attributes.
+
+	* config/i386/winnt.c (i386_pe_output_labelref): Fix indents.
+
 2003-07-03 Uwe Stieber <uwe@kaos-group.de>
 
 	* config/kaos.h (CPP_PREDEFINES): Delete.

gcc/config/i386/winnt.c

@@ -3,19 +3,20 @@
    Copyright (C) 1995, 1997, 1998, 1999, 2000, 2001, 2002, 2003
    Free Software Foundation, Inc.
 
-This file is part of GNU CC.
+This file is part of GCC.
 
-GNU CC is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2, or (at your option) any later
+version.
 
-GNU CC is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
 
 You should have received a copy of the GNU General Public License
+
 along with GNU CC; see the file COPYING.  If not, write to
 the Free Software Foundation, 59 Temple Place - Suite 330,
 Boston, MA 02111-1307, USA.  */
@@ -66,16 +67,18 @@ void i386_pe_mark_dllimport PARAMS ((tree));
 /* Handle a "dllimport" or "dllexport" attribute;
    arguments as in struct attribute_spec.handler.  */
 tree
-ix86_handle_dll_attribute (node, name, args, flags, no_add_attrs)
-     tree *node;
+ix86_handle_dll_attribute (pnode, name, args, flags, no_add_attrs)
+     tree * pnode;
      tree name;
      tree args;
      int flags;
      bool *no_add_attrs;
 {
+  tree node = *pnode;
+
   /* These attributes may apply to structure and union types being created,
      but otherwise should pass to the declaration involved.  */
-  if (!DECL_P (*node))
+  if (!DECL_P (node))
     {
       if (flags & ((int) ATTR_FLAG_DECL_NEXT | (int) ATTR_FLAG_FUNCTION_NEXT
 		   | (int) ATTR_FLAG_ARRAY_NEXT))
@@ -83,20 +86,58 @@ ix86_handle_dll_attribute (node, name, args, flags, no_add_attrs)
 	  *no_add_attrs = true;
 	  return tree_cons (name, args, NULL_TREE);
 	}
-      if (TREE_CODE (*node) != RECORD_TYPE && TREE_CODE (*node) != UNION_TYPE)
+      if (TREE_CODE (node) != RECORD_TYPE && TREE_CODE (node) != UNION_TYPE)
 	{
 	  warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
 	  *no_add_attrs = true;
 	}
+
+      return NULL_TREE;
+    }
+
+  /* Report error on dllimport ambiguities seen now before they cause
+     any damage.  */
+  else if (is_attribute_p ("dllimport", name))
+    {
+      /* Like MS, treat definition of dllimported variables and
+	 non-inlined functions on declaration as syntax errors.
+	 We allow the attribute for function definitions if declared
+	 inline, but just ignore it in i386_pe_dllimport_p.  */
+      if (TREE_CODE (node) == FUNCTION_DECL  && DECL_INITIAL (node)
+          && !DECL_INLINE (node))
+	{
+	  error ("%Hfunction `%D' definition is marked dllimport.",
+		 &DECL_SOURCE_LOCATION (node), node);
+	  *no_add_attrs = true;
+	}
+
+      else if (TREE_CODE (node) == VAR_DECL)
+	{
+	  if (DECL_INITIAL (node))
+	    {
+	      error ("%Hvariable `%D' definition is marked dllimport.",
+		     &DECL_SOURCE_LOCATION (node), node);
+	      *no_add_attrs = true;
 	    }
 
 	  /* `extern' needn't be specified with dllimport.
 	     Specify `extern' now and hope for the best.  Sigh.  */
-  else if (TREE_CODE (*node) == VAR_DECL
-	   && is_attribute_p ("dllimport", name))
+	  DECL_EXTERNAL (node) = 1; 
+	  /* Also, implicitly give dllimport'd variables declared within
+	     a function global scope, unless declared static.  */
+	  if (current_function_decl != NULL_TREE && !TREE_STATIC (node))
+  	    TREE_PUBLIC (node) = 1;
+	}
+    }
+
+  /*  Report error if symbol is not accessible at global scope. */
+  if (!TREE_PUBLIC (node)
+      && (TREE_CODE (node) == VAR_DECL
+	  || TREE_CODE (node) == FUNCTION_DECL)) 
     {
-      DECL_EXTERNAL (*node) = 1;
-      TREE_PUBLIC (*node) = 1;
+      error ("%Hexternal linkage required for symbol '%D' because of '%s' attribute.",
+	       &DECL_SOURCE_LOCATION (node), node, IDENTIFIER_POINTER (name));
+      *no_add_attrs = true;
     }
 
   return NULL_TREE;
@@ -181,6 +222,7 @@ i386_pe_dllimport_p (decl)
      tree decl;
 {
   tree imp;
+  int context_imp = 0;
 
   if (TREE_CODE (decl) == FUNCTION_DECL
       && TARGET_NOP_FUN_DLLIMPORT)
@@ -189,16 +231,64 @@ i386_pe_dllimport_p (decl)
   if (TREE_CODE (decl) != VAR_DECL
       && TREE_CODE (decl) != FUNCTION_DECL)
     return 0;
+
   imp = lookup_attribute ("dllimport", DECL_ATTRIBUTES (decl));
-  if (imp)
-    return 1;
 
   /* Class members get the dllimport status of their class.  */
-  if (associated_type (decl))
+  if (!imp && associated_type (decl))
     {
       imp = lookup_attribute ("dllimport",
 			      TYPE_ATTRIBUTES (associated_type (decl)));
       if (imp)
+	context_imp = 1;
+    }
+
+  if (imp)
+    {
+      /* Don't mark defined functions as dllimport.  If the definition
+	 itself was marked with dllimport, than ix86_handle_dll_attribute
+	 reports an error. This handles the case when the definition
+	 overrides an earlier declaration.  */
+      if (TREE_CODE (decl) ==  FUNCTION_DECL && DECL_INITIAL (decl)
+	  && !DECL_INLINE (decl))
+	{
+	   /* Don't warn about artificial methods.  */
+	  if (!DECL_ARTIFICIAL (decl))
+	    warning ("%H function '%D' is defined after prior declaration as dllimport: attribute ignored",
+		     &DECL_SOURCE_LOCATION (decl), decl);
+	  return 0;
+	}
+
+      /* We ignore the dllimport attribute for inline member functions.
+	 This differs from MSVC behaviour which treats it like GNUC
+     	 'extern inline' extension.   */
+      else if (TREE_CODE (decl) == FUNCTION_DECL && DECL_INLINE (decl))
+        {
+	  if (extra_warnings)
+	    warning ("%Hinline function '%D' is declared as dllimport: attribute ignored.", 
+		     &DECL_SOURCE_LOCATION (decl), decl);
+	  return 0;
+	}
+
+      /*  Don't allow definitions of static data members in dllimport class,
+	  Just ignore attribute for vtable data.  */
+      else if (TREE_CODE (decl) == VAR_DECL
+	       && TREE_STATIC (decl) && TREE_PUBLIC (decl)
+	       && !DECL_EXTERNAL (decl) && context_imp)
+	{
+	  if (!DECL_VIRTUAL_P (decl))
+	      error ("%Hdefinition of static data member '%D' of dllimport'd class.", 
+		     &DECL_SOURCE_LOCATION (decl), decl);
+           return 0;
+	}
+
+      /* Since we can't treat a pointer to a dllimport'd symbol as a
+	 constant address, we turn off the attribute on C++ virtual
+	 methods to allow creation of vtables using thunks. */
+      else if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE
+	       && (DECL_VIRTUAL_P (decl)))
+           return 0;
+
       return 1;
     }
 
@@ -246,8 +336,13 @@ i386_pe_mark_dllexport (decl)
   else
     abort ();
   if (i386_pe_dllimport_name_p (oldname))
+    {
+      warning ("%Hinconsistent dll linkage for '%D, dllexport assumed.",
+	       &DECL_SOURCE_LOCATION (decl), decl);
      /* Remove DLL_IMPORT_PREFIX.  */
       oldname += strlen (DLL_IMPORT_PREFIX);
+      DECL_NON_ADDR_CONST_P (decl) = 0;
+    }
   else if (i386_pe_dllexport_name_p (oldname))
     return;  /*  already done  */
 
@@ -291,41 +386,16 @@ i386_pe_mark_dllimport (decl)
     }
   else if (i386_pe_dllimport_name_p (oldname))
     {
-      /* Already done, but force correct linkage since the redeclaration 
-         might have omitted explicit extern.  Sigh.  */
-      if (TREE_CODE (decl) == VAR_DECL
-	  /* ??? Is this test for vtables needed?  */
-	  && !DECL_VIRTUAL_P (decl))
+      /* Already done, but do a sanity check to prevent assembler errors. */
+      if (!DECL_EXTERNAL (decl) || !TREE_PUBLIC (decl))
 	{
-	  DECL_EXTERNAL (decl) = 1;
-	  TREE_PUBLIC (decl) = 1;
+	  error ("%Hfailure in redeclaration of '%D': dllimport'd symbol lacks external linkage.", 
+		 &DECL_SOURCE_LOCATION (decl), decl);
+	  abort();
 	}
       return;
     }
 
-  /* ??? One can well ask why we're making these checks here,
-     and that would be a good question.  */
-
-  /* Imported variables can't be initialized. Note that C++ classes
-     are marked initial, so we need to check.  */
-  if (TREE_CODE (decl) == VAR_DECL
-      && !DECL_VIRTUAL_P (decl)
-      && (DECL_INITIAL (decl)
-          && ! TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl))))
-    {
-      error_with_decl (decl, "initialized variable `%s' is marked dllimport");
-      return;
-    }
-  /* Nor can they be static.  */
-  if (TREE_CODE (decl) == VAR_DECL
-      /* ??? Is this test for vtables needed?  */
-      && !DECL_VIRTUAL_P (decl)
-      && 0 /*???*/)
-    {
-      error_with_decl (decl, "static variable `%s' is marked dllimport");
-      return;
-    }
-
   newname = alloca (strlen (DLL_IMPORT_PREFIX) + strlen (oldname) + 1);
   sprintf (newname, "%s%s", DLL_IMPORT_PREFIX, oldname);
 
@@ -466,6 +536,12 @@ i386_pe_encode_section_info (decl, rtl, first)
       tree idp = get_identifier (oldname + strlen (DLL_IMPORT_PREFIX));
       rtx newrtl = gen_rtx (SYMBOL_REF, Pmode, IDENTIFIER_POINTER (idp));
 
+      warning ("%H%s '%D' %s after being referenced with dllimport linkage.",
+	         &DECL_SOURCE_LOCATION (decl),
+	         TREE_CODE (decl) == VAR_DECL ? "variable" : "function", 
+	         decl, (DECL_INITIAL (decl) || !DECL_EXTERNAL (decl))
+			? "defined locally" : "redeclared without dllimport attribute");
+
       XEXP (DECL_RTL (decl), 0) = newrtl;
 
       DECL_NON_ADDR_CONST_P (decl) = 0;
@@ -796,4 +872,3 @@ i386_pe_file_end ()
 	}
     }
 }
-

gcc/doc/extend.texi

@@ -2563,6 +2563,67 @@ use the normal calling convention based on @code{jsr} and @code{rts}.
 This attribute can be used to cancel the effect of the @option{-mlong-calls}
 option.
 
+@item dllimport
+@cindex @code{__declspec(dllimport)}
+On Windows targets, the @code{dllimport} attribute causes the compiler
+to reference a function or variable via a global pointer to a pointer
+that is set up by the Windows dll library. The pointer name is formed by
+combining @code{_imp__} and the function or variable name. The attribute
+implies @code{extern} storage.
+
+Currently, the attribute is ignored for inlined functions. If the
+attribute is applied to a symbol @emph{definition}, an error is reported.
+If a symbol previously declared @code{dllimport} is later defined, the
+attribute is ignored in subsequent references, and a warning is emitted.
+The attribute is also overriden by a subsequent declaration as
+@code{dllexport}. 
+
+When applied to C++ classes, the attribute marks non-inlined
+member functions and static data members as imports.  However, the
+attribute is ignored for virtual methods to allow creation of vtables
+using thunks.
+
+On cygwin, mingw and arm-pe targets, @code{__declspec(dllimport)} is
+recognized as a synonym for @code{__attribute__ ((dllimport))} for
+compatibility with other Windows compilers.
+
+The use of the @code{dllimport} attribute on functions is not necessary,
+but provides a small performance benefit by eliminating a thunk in the
+dll. The use of the @code{dllimport} attribute on imported variables was
+required on older versions of GNU ld, but can now be avoided by passing
+the @option{--enable-auto-import} switch to ld. As with functions, using
+the attribute for a variable eliminates a thunk in the dll. 
+
+One drawback to using this attribute is that a pointer to a function or
+variable marked as dllimport cannot be used as a constant address. The
+attribute can be disabled for functions by setting the
+@option{-mnop-fun-dllimport} flag.
+
+@item dllexport
+@cindex @code{__declspec(dllexport)}
+On Windows targets the @code{dllexport} attribute causes the compiler to
+provide a global pointer to a pointer in a dll, so that it can be
+referenced with the @code{dllimport} attribute. The pointer name is
+formed by combining @code{_imp__} and the function or variable name.
+
+Currently, the @code{dllexport}attribute is ignored for inlined
+functions, but export can be forced by using the
+@option{-fkeep-inline-functions} flag. The attribute is also ignored for
+undefined symbols.
+
+When applied to C++ classes. the attribute marks defined non-inlined
+member functions and static data members as exports. Static consts
+initialized in-class are not marked unless they are also defined
+out-of-class.
+
+On cygwin, mingw and arm-pe targets, @code{__declspec(dllexport)} is
+recognized as a synonym for @code{__attribute__ ((dllexport))} for
+compatibility with other Windows compilers.
+
+Alternative methods for including the symbol in the dll's export table
+are to use a .def file with an @code{EXPORTS} section or, with GNU ld,
+using the @option{--export-all} linker flag.
+
 @end table
 
 You can specify multiple attributes in a declaration by separating them
@@ -3163,7 +3224,7 @@ section, consider using the facilities of the linker instead.
 
 @item shared
 @cindex @code{shared} variable attribute
-On Windows NT, in addition to putting variable definitions in a named
+On Windows, in addition to putting variable definitions in a named
 section, the section can also be shared among all running copies of an
 executable or DLL@.  For example, this small program defines shared data
 by putting it in a named section @code{shared} and marking the section
@@ -3186,7 +3247,7 @@ You may only use the @code{shared} attribute along with @code{section}
 attribute with a fully initialized global definition because of the way
 linkers work.  See @code{section} attribute for more information.
 
-The @code{shared} attribute is only available on Windows NT@.
+The @code{shared} attribute is only available on Windows@.
 
 @item tls_model ("@var{tls_model}")
 @cindex @code{tls_model} attribute
@@ -3243,6 +3304,13 @@ the @code{int}.
 
 @item weak
 The @code{weak} attribute is described in @xref{Function Attributes}.
+
+@item dllimport
+The @code{dllimport} attribute is described in @xref{Function Attributes}.
+
+@item dlexport
+The @code{dllexport} attribute is described in @xref{Function Attributes}.
+
 @end table
 
 @subsection M32R/D Variable Attributes