c++: Adding exception specs can changed dependentness

Making an exception variant can cause a non-dependent function type to
become dependent (since c++17 eh-specs are part of the type).  The
same is (possibly?) true for adding a late return type.  Fixed thusly.
My upcoming local extern-decl changes have a test case that covers
this (which was how I found it).

	gcc/cp/
	* tree.c (build_cp_fntype_variant): Clear
	TYPE_DEPENDENT_P_VALID if necessary.

diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 8b7c6798ee968e30e55ef5f80f3ca08cb5810e71..074fa0c025e6a25a81995b10b2a2322c9d58fc3d 100644 (file)
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -2638,6 +2638,9 @@ build_cp_fntype_variant (tree type, cp_ref_qualifier rqual,
 
   /* Need to build a new variant.  */
   v = build_variant_type_copy (type);
+  if (!TYPE_DEPENDENT_P (v))
+    /* We no longer know that it's not type-dependent.  */
+    TYPE_DEPENDENT_P_VALID (v) = false;
   TYPE_RAISES_EXCEPTIONS (v) = raises;
   TYPE_HAS_LATE_RETURN_TYPE (v) = late;
   switch (rqual)