[gcc r12-1790] c: Fix C cast error-recovery [PR101171]

[gcc r12-1790] c: Fix C cast error-recovery [PR101171]

[Jakub Jelinek]

https://gcc.gnu.org/g:fdc5522fb04b4a820b28c4d1f16f54897f5978de

commit r12-1790-gfdc5522fb04b4a820b28c4d1f16f54897f5978de
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jun 24 15:55:28 2021 +0200

    c: Fix C cast error-recovery [PR101171]
    
    The following testcase ICEs during error-recovery, as build_c_cast calls
    note_integer_operands on error_mark_node and that wraps it into
    C_MAYBE_CONST_EXPR which is unexpected and causes ICE later on.
    Seems most other callers of note_integer_operands check early if something
    is error_mark_node and return before calling note_integer_operands on it.
    
    The following patch fixes it by not calling on error_mark_node, another
    possibility would be to handle error_mark_node in note_integer_operands and
    just return it.
    
    2021-06-24  Jakub Jelinek  <jakub@redhat.com>
    
            PR c/101171
            * c-typeck.c (build_c_cast): Don't call note_integer_operands on
            error_mark_node.
    
            * gcc.dg/pr101171.c: New test.

Diff:
---
 gcc/c/c-typeck.c                |  1 +
 gcc/testsuite/gcc.dg/pr101171.c | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index d0d36c3b081..d079ce4b05b 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -6131,6 +6131,7 @@ build_c_cast (location_t loc, tree type, tree expr)
      return value reflects this.  */
   if (int_operands
       && INTEGRAL_TYPE_P (type)
+      && value != error_mark_node
       && !EXPR_INT_CONST_OPERANDS (value))
     value = note_integer_operands (value);
 
diff --git a/gcc/testsuite/gcc.dg/pr101171.c b/gcc/testsuite/gcc.dg/pr101171.c
new file mode 100644
index 00000000000..8d2bcabd3e4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr101171.c
@@ -0,0 +1,13 @@
+/* PR c/101171 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+extern void foo (void);
+int x = 0x1234;
+
+void
+bar (void)
+{
+  if (x != (sizeof ((enum T) 0x1234)))	/* { dg-error "conversion to incomplete type" } */
+    foo ();
+}