c++: Support thread_local statics in header modules [PR113292]

Currently, thread_locals in header modules cause ICEs. This patch makes
the required changes for them to work successfully.

This requires additionally writing the DECL_TLS_MODEL for thread-local
variables to the module interface, and the TLS wrapper function needs to
have its DECL_BEFRIENDING_CLASSES written too as this is used to
retrieve what VAR_DECL it's a wrapper for when emitting a definition at
end of TU processing.

	PR c++/113292

gcc/cp/ChangeLog:
	* decl2.cc (get_tls_wrapper_fn): Set DECL_CONTEXT.
	(c_parse_final_cleanups): Suppress warning for no definition of
	TLS wrapper functions in header modules.
	* module.cc (trees_out::lang_decl_vals): Write wrapped variable
	for TLS wrapper functions.
	(trees_in::lang_decl_vals): Read it.
	(trees_out::decl_value): Write TLS model for thread-local vars.
	(trees_in::decl_value): Read it for new decls. Remember to emit
	definitions of TLS wrapper functions later.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/pr113292_a.H: New test.
	* g++.dg/modules/pr113292_b.C: New test.
	* g++.dg/modules/pr113292_c.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index aa75e28..350ad15 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -6950,6 +6950,9 @@ trees_out::lang_decl_vals (tree t)
 	  if (streaming_p ())
 	    wi (lang->u.fn.u5.fixed_offset);
 	}
+      else if (decl_tls_wrapper_p (t))
+	/* The wrapped variable.  */
+	WT (lang->u.fn.befriending_classes);
       else
 	WT (lang->u.fn.u5.cloned_function);
 
@@ -7029,6 +7032,8 @@ trees_in::lang_decl_vals (tree t)
 	  RT (lang->u.fn.befriending_classes);
 	  lang->u.fn.u5.fixed_offset = wi ();
 	}
+      else if (decl_tls_wrapper_p (t))
+	RT (lang->u.fn.befriending_classes);
       else
 	RT (lang->u.fn.u5.cloned_function);
 
@@ -7928,6 +7933,9 @@ trees_out::decl_value (tree decl, depset *dep)
 				   decl, cloned_p ? "" : "not ");
     }
 
+  if (streaming_p () && VAR_P (decl) && CP_DECL_THREAD_LOCAL_P (decl))
+    u (decl_tls_model (decl));
+
   if (streaming_p ())
     dump (dumper::TREE) && dump ("Written decl:%d %C:%N", tag,
 				 TREE_CODE (decl), decl);
@@ -8275,6 +8283,13 @@ trees_in::decl_value ()
 	   look like templates.  */
 	if (!install_implicit_member (inner))
 	  set_overrun ();
+
+      /* When importing a TLS wrapper from a header unit, we haven't
+	 actually emitted its definition yet. Remember it so we can
+	 do this later.  */
+      if (state->is_header ()
+	  && decl_tls_wrapper_p (decl))
+	note_vague_linkage_fn (decl);
     }
   else
     {
@@ -8358,6 +8373,13 @@ trees_in::decl_value ()
 	}
     }
 
+  if (VAR_P (decl) && CP_DECL_THREAD_LOCAL_P (decl))
+    {
+      enum tls_model model = tls_model (u ());
+      if (is_new)
+	set_decl_tls_model (decl, model);
+    }
+
   if (!NAMESPACE_SCOPE_P (inner)
       && ((TREE_CODE (inner) == TYPE_DECL
 	   && !is_typedef