c++/modules: Fix exporting temploid friends in header units [PR118582]

When we started streaming the bit to handle merging of imported temploid
friends in r15-2807, I unthinkingly only streamed it in the
'!state->is_header ()' case.

This patch reworks the streaming logic to ensure that this data is
always streamed, including for unique entities (in case that ever comes
up somehow).  This does make the streaming slightly less efficient, as
functions and types will need an extra byte, but this doesn't appear to
make a huge difference to the size of the resulting module; the 'std'
module on my machine grows by 0.2% from 30671136 to 30730144 bytes.

	PR c++/118582

gcc/cp/ChangeLog:

	* module.cc (trees_out::decl_value): Always stream
	imported_temploid_friends information.
	(trees_in::decl_value): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/pr118582_a.H: New test.
	* g++.dg/modules/pr118582_b.H: New test.
	* g++.dg/modules/pr118582_c.H: New test.

Signed-off-by: Nathaniel Shead <[email protected]>

Author: wreien

gcc/cp/module.cc

@@ -2791,7 +2791,7 @@ static keyed_map_t *keyed_table;
 
 /* Instantiations of temploid friends imported from another module
    need to be attached to the same module as the temploid.  This maps
-   these decls to the temploid they are instantiated them, as there is
+   these decls to the temploid they are instantiated from, as there is
    no other easy way to get this information.  */
 static GTY((cache)) decl_tree_cache_map *imported_temploid_friends;
 
@@ -7961,7 +7961,6 @@ trees_out::decl_value (tree decl, depset *dep)
     }
 
   merge_kind mk = get_merge_kind (decl, dep);
-  bool is_imported_temploid_friend = imported_temploid_friends->get (decl);
 
   if (CHECKING_P)
     {
@@ -7998,10 +7997,6 @@ trees_out::decl_value (tree decl, depset *dep)
 		is_attached = true;
 
 	      bits.b (is_attached);
-
-	      /* Also tell the importer whether this is an imported temploid
-		 friend, which has implications for merging.  */
-	      bits.b (is_imported_temploid_friend);
 	    }
 	  bits.b (dep && dep->has_defn ());
 	}
@@ -8087,6 +8082,16 @@ trees_out::decl_value (tree decl, depset *dep)
   tree container = decl_container (decl);
   unsigned tpl_levels = 0;
 
+  /* Also tell the importer whether this is a temploid friend attached
+     to a different module (which has implications for merging), so that
+     importers can reconstruct this information on stream-in.  */
+  if (TREE_CODE (inner) == FUNCTION_DECL || TREE_CODE (inner) == TYPE_DECL)
+    {
+      tree* temploid_friend_slot = imported_temploid_friends->get (decl);
+      gcc_checking_assert (!temploid_friend_slot || *temploid_friend_slot);
+      tree_node (temploid_friend_slot ? *temploid_friend_slot : NULL_TREE);
+    }
+
   {
     auto wmk = make_temp_override (dep_hash->writing_merge_key, true);
     if (decl != inner)
@@ -8182,14 +8187,6 @@ trees_out::decl_value (tree decl, depset *dep)
 	}
     }
 
-  if (is_imported_temploid_friend)
-    {
-      /* Write imported temploid friends so that importers can reconstruct
-	 this information on stream-in.  */
-      tree* slot = imported_temploid_friends->get (decl);
-      tree_node (*slot);
-    }
-
   bool is_typedef = false;
   if (!type && TREE_CODE (inner) == TYPE_DECL)
     {
@@ -8266,7 +8263,6 @@ trees_in::decl_value ()
 {
   int tag = 0;
   bool is_attached = false;
-  bool is_imported_temploid_friend = false;
   bool has_defn = false;
   unsigned mk_u = u ();
   if (mk_u >= MK_hwm || !merge_kind_name[mk_u])
@@ -8287,10 +8283,7 @@ trees_in::decl_value ()
 	{
 	  bits_in bits = stream_bits ();
 	  if (!(mk & MK_template_mask) && !state->is_header ())
-	    {
-	      is_attached = bits.b ();
-	      is_imported_temploid_friend = bits.b ();
-	    }
+	    is_attached = bits.b ();
 
 	  has_defn = bits.b ();
 	}
@@ -8385,6 +8378,12 @@ trees_in::decl_value ()
   tree container = decl_container ();
   unsigned tpl_levels = 0;
 
+  /* If this is an imported temploid friend, get the owning decl its
+     attachment is determined by (or NULL_TREE otherwise).  */
+  tree temploid_friend = NULL_TREE;
+  if (TREE_CODE (inner) == FUNCTION_DECL || TREE_CODE (inner) == TYPE_DECL)
+    temploid_friend = tree_node ();
+
   /* Figure out if this decl is already known about.  */
   int parm_tag = 0;
 
@@ -8395,7 +8394,7 @@ trees_in::decl_value ()
     parm_tag = fn_parms_init (inner);
 
   tree existing = key_mergeable (tag, mk, decl, inner, type, container,
-				 is_attached, is_imported_temploid_friend);
+				 is_attached, temploid_friend);
   tree existing_inner = existing;
   if (existing)
     {
@@ -8500,11 +8499,6 @@ trees_in::decl_value ()
 	}
     }
 
-  if (is_imported_temploid_friend)
-    if (tree owner = tree_node ())
-      if (is_new)
-	imported_temploid_friends->put (decl, owner);
-
   /* Regular typedefs will have a NULL TREE_TYPE at this point.  */
   unsigned tdef_flags = 0;
   bool is_typedef = false;
@@ -8530,6 +8524,9 @@ trees_in::decl_value ()
 	  DECL_MODULE_IMPORT_P (inner) = true;
 	}
 
+      if (temploid_friend)
+	imported_temploid_friends->put (decl, temploid_friend);
+
       if (spec.spec)
 	set_constraints (decl, spec.spec);
 

gcc/testsuite/g++.dg/modules/pr118582_a.H

@@ -0,0 +1,16 @@
+// PR c++/118582
+// { dg-additional-options "-fmodule-header -fno-module-lazy -std=c++20" }
+// { dg-module-cmi {} }
+
+template <typename> struct I;
+
+template <typename T>
+  requires (!requires { T::x; })
+struct I<T> {
+  using type = int;
+};
+
+template <typename>
+struct R {
+  friend void f();
+};

gcc/testsuite/g++.dg/modules/pr118582_b.H

@@ -0,0 +1,6 @@
+// PR c++/118582
+// { dg-additional-options "-fmodule-header -fno-module-lazy -std=c++20" }
+// { dg-module-cmi {} }
+
+import "pr118582_a.H";
+using T = I<R<int>>::type;

gcc/testsuite/g++.dg/modules/pr118582_c.H

@@ -0,0 +1,5 @@
+// PR c++/118582
+// { dg-additional-options "-fmodule-header -fno-module-lazy -std=c++20" }
+// { dg-module-cmi {} }
+
+import "pr118582_b.H";