[gcc r12-4527] c++: Fix up push_local_extern_decl_alias error recovery [PR102642]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:424945258d1778617b5d3d5273f6e1c10e718f80

commit r12-4527-g424945258d1778617b5d3d5273f6e1c10e718f80
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Oct 20 08:38:58 2021 +0200

    c++: Fix up push_local_extern_decl_alias error recovery [PR102642]
    
    My recent push_local_extern_decl_alias change broke error-recovery,
    do_pushdecl can return error_mark_node and set_decl_tls_model can't be
    called on that.  There are other code paths that store error_mark_node
    into DECL_LOCAL_DECL_ALIAS, with the intent to differentiate the cases
    where we haven't yet tried to push it into the namespace scope (NULL)
    and one where we have tried it but it failed (error_mark_node), but looking
    around, there are other spots where we call functions or do processing
    which doesn't tolerate error_mark_node.
    
    So, the first hunk with the testcase fixes the testcase, the others
    fix what I've spotted and the fix was easy to figure out (there are I think
    3 other spots mainly for function multiversioning).
    
    2021-10-20  Jakub Jelinek  <jakub@redhat.com>
    
            PR c++/102642
            * name-lookup.c (push_local_extern_decl_alias): Don't call
            set_decl_tls_model on error_mark_node.
            * decl.c (make_rtl_for_nonlocal_decl): Don't call
            set_user_assembler_name on error_mark_node.
            * parser.c (cp_parser_oacc_declare): Ignore DECL_LOCAL_DECL_ALIAS
            if it is error_mark_node.
            (cp_parser_omp_declare_target): Likewise.
    
            * g++.dg/tls/pr102642.C: New test.

Diff:
---
 gcc/cp/decl.c                       |  3 ++-
 gcc/cp/name-lookup.c                |  4 +++-
 gcc/cp/parser.c                     |  6 ++++--
 gcc/testsuite/g++.dg/tls/pr102642.C | 10 ++++++++++
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 242429d9ef4..8a45411c995 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7373,7 +7373,8 @@ make_rtl_for_nonlocal_decl (tree decl, tree init, const char* asmspec)
 		 This is horrible, as we're affecting a
 		 possibly-shared decl.  Again, a one-true-decl
 		 model breaks down.  */
-	      set_user_assembler_name (ns_decl, asmspec);
+	      if (ns_decl != error_mark_node)
+		set_user_assembler_name (ns_decl, asmspec);
 	}
     }
 
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index c414a1091b4..035bcf51278 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -3474,7 +3474,9 @@ push_local_extern_decl_alias (tree decl)
 	  push_nested_namespace (ns);
 	  alias = do_pushdecl (alias, /* hiding= */true);
 	  pop_nested_namespace (ns);
-	  if (VAR_P (decl) && CP_DECL_THREAD_LOCAL_P (decl))
+	  if (VAR_P (decl)
+	      && CP_DECL_THREAD_LOCAL_P (decl)
+	      && alias != error_mark_node)
 	    set_decl_tls_model (alias, DECL_TLS_MODEL (decl));
 	}
     }
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 865778e4d30..9c7ed65f55c 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -44437,7 +44437,8 @@ cp_parser_oacc_declare (cp_parser *parser, cp_token *pragma_tok)
 	       dependent local extern variable decls are as rare as
 	       hen's teeth.  */
 	    if (auto alias = DECL_LOCAL_DECL_ALIAS (decl))
-	      decl = alias;
+	      if (alias != error_mark_node)
+		decl = alias;
 
 	  if (OMP_CLAUSE_MAP_KIND (t) == GOMP_MAP_LINK)
 	    id = get_identifier ("omp declare target link");
@@ -45665,7 +45666,8 @@ cp_parser_omp_declare_target (cp_parser *parser, cp_token *pragma_tok)
       if (VAR_OR_FUNCTION_DECL_P (t)
 	  && DECL_LOCAL_DECL_P (t)
 	  && DECL_LANG_SPECIFIC (t)
-	  && DECL_LOCAL_DECL_ALIAS (t))
+	  && DECL_LOCAL_DECL_ALIAS (t)
+	  && DECL_LOCAL_DECL_ALIAS (t) != error_mark_node)
 	handle_omp_declare_target_clause (c, DECL_LOCAL_DECL_ALIAS (t),
 					  device_type);
     }
diff --git a/gcc/testsuite/g++.dg/tls/pr102642.C b/gcc/testsuite/g++.dg/tls/pr102642.C
new file mode 100644
index 00000000000..e3236d3dfdb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tls/pr102642.C
@@ -0,0 +1,10 @@
+// PR c++/102642
+// { dg-do compile { target c++11 } }
+
+thread_local int *z;		// { dg-message "previous declaration" }
+
+void
+foo ()
+{
+  extern thread_local int z;	// { dg-error "conflicting declaration" }
+}