From dd6f588a7b8878d677af51ff4d1c1e3f9f6f40db Mon Sep 17 00:00:00 2001
From: Nathan Sidwell <nathan@acm.org>
Date: Mon, 5 Apr 2021 07:51:28 -0700
Subject: [PATCH] c++: Unneeded export query [PR 99380]

This problem got introduced fixing a module numbering problem.  When
preprocessing a header unit, we don't need to send an EXPORT query
unless we're also determining dependencies, or the mapper asked us
to.  Sadly the testsuite isn't set up to test this kind of subtlety.
I manually did that with stdin/stdout.

	PR c++/99380
	gcc/cp/
	* module.cc (name_pending_imports): Drop 'atend' parm.  Don't
	query export when not needed.
	(preprocess_module, preprocessed_module): Adjust.
---
 gcc/cp/module.cc | 70 ++++++++++++++++++++++++++++--------------------
 1 file changed, 41 insertions(+), 29 deletions(-)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index d5b7d28ded5..c80c7bcc70f 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19262,15 +19262,11 @@ module_begin_main_file (cpp_reader *reader, line_maps *lmaps,
    filenames.   */
 
 static void
-name_pending_imports (cpp_reader *reader, bool at_end)
+name_pending_imports (cpp_reader *reader)
 {
   auto *mapper = get_mapper (cpp_main_loc (reader));
 
-  bool only_headers = (flag_preprocess_only
-		       && !bool (mapper->get_flags () & Cody::Flags::NameOnly)
-		       && !cpp_get_deps (reader));
-  if (at_end
-      && (!vec_safe_length (pending_imports) || only_headers))
+  if (!vec_safe_length (pending_imports))
     /* Not doing anything.  */
     return;
 
@@ -19278,40 +19274,56 @@ name_pending_imports (cpp_reader *reader, bool at_end)
 
   auto n = dump.push (NULL);
   dump () && dump ("Resolving direct import names");
+  bool want_deps = (bool (mapper->get_flags () & Cody::Flags::NameOnly)
+		    || cpp_get_deps (reader));
+  bool any = false;
 
-  mapper->Cork ();
   for (unsigned ix = 0; ix != pending_imports->length (); ix++)
     {
       module_state *module = (*pending_imports)[ix];
       gcc_checking_assert (module->is_direct ());
-      if (!module->filename
-	  && !module->visited_p
-	  && (module->is_header () || !only_headers))
+      if (!module->filename && !module->visited_p)
 	{
-	  module->visited_p = true;
-	  Cody::Flags flags = (flag_preprocess_only
-			       ? Cody::Flags::None : Cody::Flags::NameOnly);
+	  bool export_p = (module->module_p
+			   && (module->is_partition () || module->exported_p));
 
-	  if (module->module_p
-	      && (module->is_partition () || module->exported_p))
+	  Cody::Flags flags = Cody::Flags::None;
+	  if (flag_preprocess_only
+	      && !(module->is_header () && !export_p))
+	    {
+	      if (!want_deps)
+		continue;
+	      flags = Cody::Flags::NameOnly;
+	    }
+
+	  if (!any)
+	    {
+	      any = true;
+	      mapper->Cork ();
+	    }
+	  if (export_p)
 	    mapper->ModuleExport (module->get_flatname (), flags);
 	  else
 	    mapper->ModuleImport (module->get_flatname (), flags);
+	  module->visited_p = true;
 	}
     }
-  
-  auto response = mapper->Uncork ();
-  auto r_iter = response.begin ();
-  for (unsigned ix = 0; ix != pending_imports->length (); ix++)
-    {
-      module_state *module = (*pending_imports)[ix];
-      if (module->visited_p)
-	{
-	  module->visited_p = false;
-	  gcc_checking_assert (!module->filename);
 
-	  module->set_filename (*r_iter);
-	  ++r_iter;
+  if (any)
+    {
+      auto response = mapper->Uncork ();
+      auto r_iter = response.begin ();
+      for (unsigned ix = 0; ix != pending_imports->length (); ix++)
+	{
+	  module_state *module = (*pending_imports)[ix];
+	  if (module->visited_p)
+	    {
+	      module->visited_p = false;
+	      gcc_checking_assert (!module->filename);
+
+	      module->set_filename (*r_iter);
+	      ++r_iter;
+	    }
 	}
     }
 
@@ -19384,7 +19396,7 @@ preprocess_module (module_state *module, location_t from_loc,
 	  unsigned n = dump.push (NULL);
 
 	  dump () && dump ("Reading %M preprocessor state", module);
-	  name_pending_imports (reader, false);
+	  name_pending_imports (reader);
 
 	  /* Preserve the state of the line-map.  */
 	  unsigned pre_hwm = LINEMAPS_ORDINARY_USED (line_table);
@@ -19446,7 +19458,7 @@ preprocessed_module (cpp_reader *reader)
 
   dump () && dump ("Completed phase-4 (tokenization) processing");
 
-  name_pending_imports (reader, true);
+  name_pending_imports (reader);
   vec_free (pending_imports);
 
   spans.maybe_init ();