PR c++/96442: Improved error recovery in enumerations.

This patch is a revised fix for PR c++/96442 providing a cleaner
solution, setting ENUM_UNDERLYING_TYPE to integer_type_node when
issuing an error, so that this invariant holds during the parser's
error recovery.

2022-06-07  Roger Sayle  <roger@nextmovesoftware.com>

gcc/cp/ChangeLog
	PR c++/96442
	* decl.cc (start_enum): When emitting a "must be integral" error,
	set ENUM_UNDERLYING_TYPE to integer_type_node, to avoid an ICE
	downstream in build_enumeration.

gcc/testsuite/ChangeLog
	PR c++/96442
	* g++.dg/parse/pr96442.C: New test case.

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 90b12d69414c851966bce0988f9ddeaa1a0bcde9..7add82aa39e37f5949700fe26b12d37dcd88506d 100644 (file)
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -16314,8 +16314,11 @@ start_enum (tree name, tree enumtype, tree underlying_type,
       else if (dependent_type_p (underlying_type))
        ENUM_UNDERLYING_TYPE (enumtype) = underlying_type;
       else
-        error ("underlying type %qT of %qT must be an integral type", 
-               underlying_type, enumtype);
+       {
+         error ("underlying type %qT of %qT must be an integral type", 
+                underlying_type, enumtype);
+         ENUM_UNDERLYING_TYPE (enumtype) = integer_type_node;
+       }
     }
 
   /* If into a template class, the returned enum is always the first

diff --git a/gcc/testsuite/g++.dg/parse/pr96442.C b/gcc/testsuite/g++.dg/parse/pr96442.C
new file mode 100644 (file)
index 0000000..235bb11
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/pr96442.C
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+enum struct a : struct {};
+template <class b> enum class a : class c{};
+enum struct a {b};
+// { dg-excess-errors "" }