[PR82155] Fix crash in dwarf2out_abstract_function

This patch is an attempt to fix the crash reported in PR82155.

When generating a C++ class method for a class that is itself nested in
a class method, dwarf2out_early_global_decl currently leaves the
existing context DIE as it is if it already exists.  However, it is
possible that this call happens at a point where this context DIE is
just a declaration that is itself not located in its own context.

From there, if dwarf2out_early_global_decl is not called on any of the
FUNCTION_DECL in the context chain, DIEs will be left badly scoped and
some (such as the nested method) will be removed by the type pruning
machinery.  As a consequence, dwarf2out_abstract_function will will
crash when called on the corresponding DECL because it asserts that the
DECL has a DIE.

This patch fixes this crash making dwarf2out_early_global_decl process
context DIEs the same way we process abstract origins for FUNCTION_DECL:
if the corresponding DIE exists but is only a declaration, call
dwarf2out_decl anyway on it so that it is turned into a more complete
DIE and so that it is relocated in the proper context.

Bootstrapped and regtested on x86_64-linux.

gcc/

	PR debug/82155
	* dwarf2out.c (dwarf2out_early_global_decl): Call dwarf2out_decl
	on the FUNCTION_DECL function context if it has a DIE that is a
	declaration.

gcc/testsuite/

	* g++.dg/pr82155.C: New testcase.

From-SVN: r253147

1 files changed, 8 insertions, 2 deletions

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index dda569f..e97ceb6 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -25490,10 +25490,16 @@ dwarf2out_early_global_decl (tree decl)
 	     so that all nested DIEs are generated at the proper scope in the
 	     first shot.  */
 	  tree context = decl_function_context (decl);
-	  if (context != NULL && lookup_decl_die (context) == NULL)
+	  if (context != NULL)
 	    {
+	      dw_die_ref context_die = lookup_decl_die (context);
 	      current_function_decl = context;
-	      dwarf2out_decl (context);
+
+	      /* Avoid emitting DIEs multiple times, but still process CONTEXT
+		 enough so that it lands in its own context.  This avoids type
+		 pruning issues later on.  */
+	      if (context_die == NULL || is_declaration_die (context_die))
+		dwarf2out_decl (context);
 	    }
 
 	  /* Emit an abstract origin of a function first.  This happens