[PATCH] c: Fix ICE for incorrect code in comptypes_verify [PR115696]

[Martin Uecker]

This adds missing code for handling error marks.


Bootstrapped and regression tested on x86_64.



    c: Fix ICE for incorrect code in comptypes_verify [PR115696]
    
    The new verification code produces an ICE for incorrect code.  Add the
    same logic as already used in comptypes to to bail out under certain
    conditions.
    
            PR c/115696
    
    gcc/c/
            * c-typeck.cc (comptypes_verify): Bail out for
            identical, empty, and erroneous input types.
    
    gcc/testsuite/
            * gcc.dg/pr115696.c: New test.

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index ffcab7df4d3..e486ac04f9c 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -1175,6 +1175,10 @@ common_type (tree t1, tree t2)
 static bool
 comptypes_verify (tree type1, tree type2)
 {
+  if (type1 == type2 || !type1 || !type2
+      || TREE_CODE (type1) == ERROR_MARK || TREE_CODE (type2) == ERROR_MARK)
+    return true;
+
   if (TYPE_CANONICAL (type1) != TYPE_CANONICAL (type2)
       && !TYPE_STRUCTURAL_EQUALITY_P (type1)
       && !TYPE_STRUCTURAL_EQUALITY_P (type2))
diff --git a/gcc/testsuite/gcc.dg/pr115696.c b/gcc/testsuite/gcc.dg/pr115696.c
new file mode 100644
index 00000000000..a7c8d87cb06
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr115696.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-Wno-implicit-int" } */
+
+a();   /* { dg-warning "no type or storage" } */
+a;     /* { dg-error "redeclared" } */
+       /* { dg-warning "no type or storage" "" { target *-*-* } .-1 } */
+a();   /* { dg-warning "no type or storage" } */