Re: [C PATCH] Remove dead code related to type compatibility across TUs.

2023-05-19 Thread Joseph Myers
On Fri, 19 May 2023, Martin Uecker via Gcc-patches wrote:

> Repost for stage 1.
> 
> 
> C: Remove dead code related to type compatibility across TUs.
> 
> Code to detect struct/unions across the same TU is not needed
> anymore. Code for determining compatibility of tagged types is
> preserved as it will be used for C2X. Some errors in the unused
> code are fixed.
> 
> Bootstrapped with no regressions for x86_64-pc-linux-gnu.
> 
> gcc/c/
> * c-decl.cc (set_type_context): Remove.
> (pop_scope, diagnose_mismatched_decls, pushdecl):
> Remove dead code.
> * c-typeck.cc (comptypes_internal): Remove dead code.
> (same_translation_unit_p): Remove.
> (tagged_types_tu_compatible_p): Some fixes.

OK.

-- 
Joseph S. Myers
jos...@codesourcery.com


[C PATCH] Remove dead code related to type compatibility across TUs.

2023-05-19 Thread Martin Uecker via Gcc-patches


Repost for stage 1.


C: Remove dead code related to type compatibility across TUs.

Code to detect struct/unions across the same TU is not needed
anymore. Code for determining compatibility of tagged types is
preserved as it will be used for C2X. Some errors in the unused
code are fixed.

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

gcc/c/
* c-decl.cc (set_type_context): Remove.
(pop_scope, diagnose_mismatched_decls, pushdecl):
Remove dead code.
* c-typeck.cc (comptypes_internal): Remove dead code.
(same_translation_unit_p): Remove.
(tagged_types_tu_compatible_p): Some fixes.

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index f63c1108ab5..70345b4b019 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -1155,16 +1155,6 @@ update_label_decls (struct c_scope *scope)
 }
 }
 
-/* Set the TYPE_CONTEXT of all of TYPE's variants to CONTEXT.  */
-
-static void
-set_type_context (tree type, tree context)
-{
-  for (type = TYPE_MAIN_VARIANT (type); type;
-   type = TYPE_NEXT_VARIANT (type))
-TYPE_CONTEXT (type) = context;
-}
-
 /* Exit a scope.  Restore the state of the identifier-decl mappings
that were in effect when this scope was entered.  Return a BLOCK
node containing all the DECLs in this scope that are of interest
@@ -1253,7 +1243,6 @@ pop_scope (void)
case ENUMERAL_TYPE:
case UNION_TYPE:
case RECORD_TYPE:
- set_type_context (p, context);
 
  /* Types may not have tag-names, in which case the type
 appears in the bindings list with b->id NULL.  */
@@ -1364,12 +1353,7 @@ pop_scope (void)
 the TRANSLATION_UNIT_DECL.  This makes same_translation_unit_p
 work.  */
  if (scope == file_scope)
-   {
  DECL_CONTEXT (p) = context;
- if (TREE_CODE (p) == TYPE_DECL
- && TREE_TYPE (p) != error_mark_node)
-   set_type_context (TREE_TYPE (p), context);
-   }
 
  gcc_fallthrough ();
  /* Parameters go in DECL_ARGUMENTS, not BLOCK_VARS, and have
@@ -2318,21 +2302,18 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
{
  if (DECL_INITIAL (olddecl))
{
- /* If both decls are in the same TU and the new declaration
-isn't overriding an extern inline reject the new decl.
-In c99, no overriding is allowed in the same translation
-unit.  */
- if ((!DECL_EXTERN_INLINE (olddecl)
-  || DECL_EXTERN_INLINE (newdecl)
-  || (!flag_gnu89_inline
-  && (!DECL_DECLARED_INLINE_P (olddecl)
-  || !lookup_attribute ("gnu_inline",
-DECL_ATTRIBUTES (olddecl)))
-  && (!DECL_DECLARED_INLINE_P (newdecl)
-  || !lookup_attribute ("gnu_inline",
-DECL_ATTRIBUTES (newdecl
- )
- && same_translation_unit_p (newdecl, olddecl))
+ /* If the new declaration isn't overriding an extern inline
+reject the new decl. In c99, no overriding is allowed
+in the same translation unit.  */
+ if (!DECL_EXTERN_INLINE (olddecl)
+ || DECL_EXTERN_INLINE (newdecl)
+ || (!flag_gnu89_inline
+ && (!DECL_DECLARED_INLINE_P (olddecl)
+ || !lookup_attribute ("gnu_inline",
+   DECL_ATTRIBUTES (olddecl)))
+ && (!DECL_DECLARED_INLINE_P (newdecl)
+ || !lookup_attribute ("gnu_inline",
+   DECL_ATTRIBUTES (newdecl)
{
  auto_diagnostic_group d;
  error ("redefinition of %q+D", newdecl);
@@ -3360,18 +3341,11 @@ pushdecl (tree x)
 type to the composite of all the types of that declaration.
 After the consistency checks, it will be reset to the
 composite of the visible types only.  */
-  if (b && (TREE_PUBLIC (x) || same_translation_unit_p (x, b->decl))
- && b->u.type)
+  if (b && b->u.type)
TREE_TYPE (b->decl) = b->u.type;
 
-  /* The point of the same_translation_unit_p check here is,
-we want to detect a duplicate decl for a construct like
-foo() { extern bar(); } ... static bar();  but not if
-they are in different translation units.  In any case,
-the static does not go in the externals scope.  */
-  if (b
- && (TREE_PUBLIC (x) || same_translation_unit_p (x, b->decl))
- && duplicate_decls (x, b->decl))
+  /* the static does not go in the externals scope.  */
+  if (b && duplicate_decls (x, b->decl))