* c-common.h (has_c_linkage): New interface.

	* c-cppbuiltin.c: Include target.h.
	(c_cpp_builtins): Define __PRAGMA_REDEFINE_EXTNAME and
	__PRAGMA_EXTERN_PREFIX when appropriate.
	* c-pragma.c: Include target.h.
	Document clarified semantics of symbol-renaming #pragmas.
	(handle_pragma_redefine_extname, handle_pragma_extern_prefix)
	(maybe_apply_renaming_pragma): Rewrite according to clarified
	semantics.  Always recognize, but do not necessarily execute.
	(init_pragma): Unconditionally register symbol-renaming pragmas.
	* system.h: Poison HANDLE_PRAGMA_REDEFINE_EXTNAME
	and HANDLE_PRAGMA_EXTERN_PREFIX.
	* target.h (struct gcc_target): Add handle_pragma_redefine_extname
	and handle_pragma_extern_prefix flags.
	* target-def.h: Add defaults for TARGET_HANDLE_PRAGMA_REDEFINE_EXTNAME
	and TARGET_HANDLE_PRAGMA_EXTERN_PREFIX.
	* Makefile.in (c-pragma.o, c-cppbuiltin.o): Update dependencies.
	* config/sol2.h: Define TARGET_HANDLE_PRAGMA_REDEFINE_EXTNAME,
	not HANDLE_PRAGMA_REDEFINE_EXTNAME.
	(TARGET_OS_CPP_BUILTINS): No need to define __PRAGMA_REDEFINE_EXTNAME.
	(TRANSFER_FROM_TRAMPOLINE): Prototype mprotect.
	* config/alpha/osf.h: Define TARGET_HANDLE_PRAGMA_EXTERN_PREFIX,
	not HANDLE_PRAGMA_EXTERN_PREFIX.
	(TARGET_OS_CPP_BUILTINS): No need to define __PRAGMA_EXTERN_PREFIX.
	* doc/extend.texi (Solaris Pragmas, Tru64 Pragmas): Combine
	into one section "Symbol-Renaming Pragmas"; clarify; document
	adjusted semantics.

	* builtins.c (expand_builtin): Do not issue error for a builtin
	with no special case code and no DECL_ASSEMBLER_NAME; just do the
	library call.
	* c-decl.c (builtin_function): Don't call make_decl_rtl.
	* c-objc-common.c (has_c_linkage): Stub implementation.
	* cgraphunit.c (cgraph_expand_function)
	(cgraph_remove_unreachable_nodes): Don't clear DECL_ARGUMENTS.

cp:
	* cp-lang.c (has_c_linkage): Implement.

	* cp-tree.h (set_mangled_name_for_decl): Don't prototype.
	* decl.c (duplicate_decls): Use COPY_DECL_RTL.
	(builtin_function_1): Don't call make_decl_rtl.
	(build_cp_library_fn): Don't call set_mangled_name_for_decl.
	(grokvardecl): Don't call mangle_decl.
	* except.c (nothrow_libfn_p): Look at DECL_NAME, not
	DECL_ASSEMBLER_NAME.
	* method.c (set_mangled_name_for_decl): Delete.
	* name-lookup.c (pushdecl): When a local extern shadows a
	file-scope declaration of the same object, give both DECLs the
	same DECL_UID.
	* typeck.c (cxx_mark_addressable): Don't set TREE_ADDRESSABLE
	on DECL_ASSEMBLER_NAME.

testsuite:
	* g++.dg/expr/enum1.C, g++.dg/opt/const3.C: Declare abort with
	extern "C".
	* g++.dg/other/pragma-re-1.C: Add comments.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@83405 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 51 insertions, 29 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 204c64b1006..6c8ea7d0754 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -7197,8 +7197,7 @@ for further explanation.
 * ARM Pragmas::
 * RS/6000 and PowerPC Pragmas::
 * Darwin Pragmas::
-* Solaris Pragmas::
-* Tru64 Pragmas::
+* Symbol-Renaming Pragmas::
 @end menu
 
 @node ARM Pragmas
@@ -7282,45 +7281,68 @@ that of the @code{unused} attribute, except that this pragma may appear
 anywhere within the variables' scopes.
 @end table
 
-@node Solaris Pragmas
-@subsection Solaris Pragmas
+@node Symbol-Renaming Pragmas
+@subsection Symbol-Renaming Pragmas
 
-For compatibility with the SunPRO compiler, the following pragma
-is supported.
+For compatibility with the Solaris and Tru64 UNIX system headers, GCC
+supports two @code{#pragma} directives which change the name used in
+assembly for a given declaration.  These pragmas are only available on
+platforms whose system headers need them.  To get this effect on all
+platforms supported by GCC, use the asm labels extension (@pxref{Asm
+Labels}).
 
 @table @code
 @item redefine_extname @var{oldname} @var{newname}
 @cindex pragma, redefine_extname
 
-This pragma gives the C function @var{oldname} the assembler label
-@var{newname}.  The pragma must appear before the function declaration.
-This pragma is equivalent to the asm labels extension (@pxref{Asm
-Labels}).  The preprocessor defines @code{__PRAGMA_REDEFINE_EXTNAME}
-if the pragma is available.
-@end table
-
-@node Tru64 Pragmas
-@subsection Tru64 Pragmas
-
-For compatibility with the Compaq C compiler, the following pragma
-is supported.
+This pragma gives the C function @var{oldname} the assembly symbol
+@var{newname}.  The preprocessor macro @code{__PRAGMA_REDEFINE_EXTNAME}
+will be defined if this pragma is available (currently only on
+Solaris).
 
-@table @code
 @item extern_prefix @var{string}
 @cindex pragma, extern_prefix
 
-This pragma renames all subsequent function and variable declarations
-such that @var{string} is prepended to the name.  This effect may be
-terminated by using another @code{extern_prefix} pragma with the
-empty string.
-
-This pragma is similar in intent to to the asm labels extension
-(@pxref{Asm Labels}) in that the system programmer wants to change
-the assembly-level ABI without changing the source-level API.  The
-preprocessor defines @code{__PRAGMA_EXTERN_PREFIX} if the pragma is
-available.
+This pragma causes all subsequent external function and variable
+declarations to have @var{string} prepended to their assembly symbols.
+This effect may be terminated with another @code{extern_prefix} pragma
+whose argument is an empty string.  The preprocessor macro
+@code{__PRAGMA_EXTERN_PREFIX} will be defined if this pragma is
+available (currently only on Tru64 UNIX).
 @end table
 
+These pragmas and the asm labels extension interact in a complicated
+manner.  Here are some corner cases you may want to be aware of.
+
+@enumerate
+@item Both pragmas silently apply only to declarations with external
+linkage.  Asm labels do not have this restriction.
+
+@item In C++, both pragmas silently apply only to declarations with
+``C'' linkage.  Again, asm labels do not have this restriction.
+
+@item If any of the three ways of changing the assembly name of a
+declaration is applied to a declaration whose assembly name has
+already been determined (either by a previous use of one of these
+features, or because the compiler needed the assembly name in order to
+generate code), and the new name is different, a warning issues and
+the name does not change.
+
+@item The @var{oldname} used by @code{#pragma redefine_extname} is
+always the C-language name.
+
+@item If @code{#pragma extern_prefix} is in effect, and a declaration
+occurs with an asm label attached, the prefix is silently ignored for
+that declaration.
+
+@item If @code{#pragma extern_prefix} and @code{#pragma redefine_extname}
+apply to the same declaration, whichever triggered first wins, and a
+warning issues if they contradict each other.  (We would like to have
+@code{#pragma redefine_extname} always win, for consistency with asm
+labels, but if @code{#pragma extern_prefix} triggers first we have no
+way of knowing that that happened.)
+@end enumerate
+
 @node Unnamed Fields
 @section Unnamed struct/union fields within structs/unions.
 @cindex struct