This is a fix for a wrong warning from -Wlto-type-mismatch that reports
a type mismatch for two built-in functions.
The avr backend has several built-ins that have the same asm name
because their assembler implementation in libgcc is exactly the same.
The prototypes might differ, however.
This patch skips the warning for built-in types as discussed in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78562#c6
Testing against avr-unknown-none, this resolves all FAILs because of
that warning, e.g. gcc.target/avr/torture/builtins-5-countlsfx.c
Ok for trunk?
Johann
gcc/lto/
PR lto/78562
* lto-symtab.c (lto_symtab_merge_decls_2): Don't diagnose type
mismatch if the two types are built-in.
Index: lto/lto-symtab.c
===================================================================
--- lto/lto-symtab.c (revision 242823)
+++ lto/lto-symtab.c (working copy)
@@ -655,6 +655,14 @@ lto_symtab_merge_decls_2 (symtab_node *f
/* Diagnose all mismatched re-declarations. */
FOR_EACH_VEC_ELT (mismatches, i, decl)
{
+ /* Do not diagnose two built-in declarations, there is no useful
+ location in that case. It also happens for AVR if two built-ins
+ use the same asm name because their libgcc assembler code is the
+ same, see PR78562. */
+ if (DECL_IS_BUILTIN (prevailing->decl)
+ && DECL_IS_BUILTIN (decl))
+ continue;
+
int level = warn_type_compatibility_p (TREE_TYPE (prevailing->decl),
TREE_TYPE (decl),
DECL_COMDAT (decl));
