[gcc r13-419] ada: gcc-if: build proper String_Pointer for Get_External_Name

[Alexandre Oliva <aoliva@gcc.gnu.org>]

https://gcc.gnu.org/g:6aaa1d573912828efed1514fbec5e1ef8a7cc3bc

commit r13-419-g6aaa1d573912828efed1514fbec5e1ef8a7cc3bc
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Fri May 13 07:48:50 2022 -0300

    ada: gcc-if: build proper String_Pointer for Get_External_Name
    
    The compiler is allowed to assume it can access String bounds, such as
    the prefix passed to Get_External_Name, even in circumstances in which
    the prefix is not going to be used and has_prefix is false, so, from
    the C side, we have to build a proper String_Template for the
    String_Pointer.
    
    
    for  gcc/ada/ChangeLog
    
            * gcc-interface/decl.cc (is_cplusplus_method): Build proper
            String for Get_External_Name.

Diff:
---
 gcc/ada/gcc-interface/decl.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/gcc-interface/decl.cc b/gcc/ada/gcc-interface/decl.cc
index 56ad4998e22..28e1ab7ce81 100644
--- a/gcc/ada/gcc-interface/decl.cc
+++ b/gcc/ada/gcc-interface/decl.cc
@@ -4956,7 +4956,8 @@ is_cplusplus_method (Entity_Id gnat_entity)
      'this' parameter is not encoded in the mangled name of a method.  */
   if (Is_Subprogram (gnat_entity) && Present (Interface_Name (gnat_entity)))
     {
-      String_Pointer sp = { NULL, NULL };
+      String_Template temp = { 0, 0 };
+      String_Pointer sp = { "", &temp };
       Get_External_Name (gnat_entity, false, sp);
 
       void *mem;