[gcc r11-3783] Objective-C++, Darwin : Make metadata 'extern "C"'.

[gcc r11-3783] Objective-C++, Darwin : Make metadata 'extern "C"'.

[Iain D Sandoe]

https://gcc.gnu.org/g:1cc7476610299eb1969f6a93ee21010ac30f5dd6

commit r11-3783-g1cc7476610299eb1969f6a93ee21010ac30f5dd6
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Tue Oct 6 18:50:22 2020 +0100

    Objective-C++, Darwin : Make metadata 'extern "C"'.
    
    For current system toolchains NeXT runtime metadata symbols are not
    mangled for Objective-C++ (i.e. they are considered to be
    'extern "C"').
    
    This change becomes essential when we start to emit metadata refs
    as hidden and weak which is required by later editions of the runtime
    and linkers.
    
    gcc/objc/ChangeLog:
    
            * objc-runtime-shared-support.c (start_var_decl): Make the
            decl_assembler_name follow the metadata name for C++ on NeXT
            runtime platforms.

Diff:
---
 gcc/objc/objc-runtime-shared-support.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/gcc/objc/objc-runtime-shared-support.c b/gcc/objc/objc-runtime-shared-support.c
index 4aecc7f339f..16d4d63c86f 100644
--- a/gcc/objc/objc-runtime-shared-support.c
+++ b/gcc/objc/objc-runtime-shared-support.c
@@ -117,14 +117,17 @@ add_field_decl (tree type, const char *name, tree **chain)
 tree
 start_var_decl (tree type, const char *name)
 {
-  tree var = build_decl (input_location,
-			 VAR_DECL, get_identifier (name), type);
-  TREE_STATIC (var) = 1;
+  tree name_id = get_identifier (name);
+  tree var = build_decl (input_location, VAR_DECL, name_id, type);
   DECL_INITIAL (var) = error_mark_node;  /* A real initializer is coming... */
+  TREE_STATIC (var) = 1;
   DECL_IGNORED_P (var) = 1;
   DECL_ARTIFICIAL (var) = 1;
   DECL_CONTEXT (var) = NULL_TREE;
 #ifdef OBJCPLUS
+  /* Meta-data for the NeXT runtime is expected to be 'extern "C"'.  */
+  if (flag_next_runtime)
+    SET_DECL_ASSEMBLER_NAME (var, name_id);
   DECL_THIS_STATIC (var) = 1; /* squash redeclaration errors */
 #endif
   return var;