Hi,
this ICE on invalid code isn't a regression, thus a patch probably
doesn't qualify for Stage 4, but IMHO I made good progress on it and I'm
sending what I have now anyway... The ICE happens during error recovery
after a sensible diagnostic for the first declaration in:
auto* foo() { return 0; }
auto* foo();
After the error, finish_function does:
apply_deduced_return_type (fndecl, void_type_node);
fntype = TREE_TYPE (fndecl);
which then is inconsistent with the auto* return type of the second
declaration and leads to an ICE in merge_types (which duplicate_decls
thought was safe to call because types_match is true (evidently:
decls_match uses fndecl_declared_return_type)). Thus, in terms of error
recovery, I think that in cases like the one at issue it makes sense not
to replace auto* after the error and leave the return type untouched:
certainly the below passes testing and avoids ICEing on the testcase at
issue and a variant of it.
Thanks,
Paolo.
//////////////////
Index: cp/decl.c
===================================================================
--- cp/decl.c (revision 246414)
+++ cp/decl.c (working copy)
@@ -15573,16 +15573,19 @@ finish_function (int flags)
if (!processing_template_decl && FNDECL_USED_AUTO (fndecl)
&& TREE_TYPE (fntype) == current_function_auto_return_pattern)
{
- if (!is_auto (current_function_auto_return_pattern)
- && !current_function_returns_value && !current_function_returns_null)
+ if (is_auto (current_function_auto_return_pattern))
{
+ apply_deduced_return_type (fndecl, void_type_node);
+ fntype = TREE_TYPE (fndecl);
+ }
+ else if (!current_function_returns_value
+ && !current_function_returns_null)
+ {
error ("no return statements in function returning %qT",
current_function_auto_return_pattern);
inform (input_location, "only plain %<auto%> return type can be "
"deduced to %<void%>");
}
- apply_deduced_return_type (fndecl, void_type_node);
- fntype = TREE_TYPE (fndecl);
}
// If this is a concept, check that the definition is reasonable.
Index: testsuite/g++.dg/cpp1y/auto-fn37.C
===================================================================
--- testsuite/g++.dg/cpp1y/auto-fn37.C (revision 0)
+++ testsuite/g++.dg/cpp1y/auto-fn37.C (working copy)
@@ -0,0 +1,5 @@
+// PR c++/80145
+// { dg-do compile { target c++14 } }
+
+auto* foo() { return 0; } // { dg-error "unable to deduce" }
+auto* foo();
Index: testsuite/g++.dg/cpp1y/auto-fn38.C
===================================================================
--- testsuite/g++.dg/cpp1y/auto-fn38.C (revision 0)
+++ testsuite/g++.dg/cpp1y/auto-fn38.C (working copy)
@@ -0,0 +1,5 @@
+// PR c++/80145
+// { dg-do compile { target c++14 } }
+
+auto* foo() { } // { dg-error "no return statements" }
+auto* foo();
