[gcc r14-4727] Fix ICE due to c_safe_arg_type_equiv_p not checking for error_mark node

[gcc r14-4727] Fix ICE due to c_safe_arg_type_equiv_p not checking for error_mark node

[Andrew Pinski]

https://gcc.gnu.org/g:11e6bcedb41359c69ee790f38b04033d236336a8

commit r14-4727-g11e6bcedb41359c69ee790f38b04033d236336a8
Author: Andrew Pinski <pinskia@gmail.com>
Date:   Sat Oct 14 13:18:00 2023 -0700

    Fix ICE due to c_safe_arg_type_equiv_p not checking for error_mark node
    
    This is a simple error recovery issue when c_safe_arg_type_equiv_p
    was added in r8-5312-gc65e18d3331aa999. The issue is that after
    an error, an argument type (of a function type) might turn
    into an error mark node and c_safe_arg_type_equiv_p was not ready
    for that. So this just adds a check for error operand for its
    arguments before getting the main variant.
    
    OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
    
            PR c/101285
    
    gcc/c/ChangeLog:
    
            * c-typeck.cc (c_safe_arg_type_equiv_p): Return true for error
            operands early.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/pr101285-1.c: New test.

Diff:
---
 gcc/c/c-typeck.cc                 |  3 +++
 gcc/testsuite/gcc.dg/pr101285-1.c | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index e55e887da146..6e044b4afbc9 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -5960,6 +5960,9 @@ handle_warn_cast_qual (location_t loc, tree type, tree otype)
 static bool
 c_safe_arg_type_equiv_p (tree t1, tree t2)
 {
+  if (error_operand_p (t1) || error_operand_p (t2))
+    return true;
+
   t1 = TYPE_MAIN_VARIANT (t1);
   t2 = TYPE_MAIN_VARIANT (t2);
 
diff --git a/gcc/testsuite/gcc.dg/pr101285-1.c b/gcc/testsuite/gcc.dg/pr101285-1.c
new file mode 100644
index 000000000000..831e35f76629
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr101285-1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-W -Wall" } */
+const int b;
+typedef void (*ft1)(int[b++]); /* { dg-error "read-only variable" } */
+void bar(int * z);
+void baz()
+{
+    (ft1) bar; /* { dg-warning "statement with no effect" } */
+}
+