This simple fix to the middle-end, resolves PR c/104506, by adding an
explicit check for error_mark_node to useless_type_conversion_p. I first
trying fixing this in the C front-end, but the type is valid at the point
that the NOP_EXPR is created, so the poisoned type leaks to the middle-end.
Returning either true or false from useless_type_conversion_p avoids the
ICE-after-error. Apologies to Andrew Pinski, I hadn't noticed that he'd
assigned this PR to himself until after my regression testing had finished.
This patch has been tested on x86_64-pc-linux-gnu with make bootstrap and
make -k check with no new failures. Ok for mainline?
2022-02-14 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
PR c/104506
* gimple-expr.cc (useless_type_conversion_p): Add a check for
error_mark_node.
gcc/testsuite/ChangeLog
PR c/104506
* gcc.dg/pr104506.c: New test case.
Roger
--
diff --git a/gcc/gimple-expr.cc b/gcc/gimple-expr.cc
index f9a650b..e63fa3c 100644
--- a/gcc/gimple-expr.cc
+++ b/gcc/gimple-expr.cc
@@ -83,6 +83,9 @@ useless_type_conversion_p (tree outer_type, tree inner_type)
return false;
}
+ if (inner_type == error_mark_node)
+ return true;
+
/* From now on qualifiers on value types do not matter. */
inner_type = TYPE_MAIN_VARIANT (inner_type);
outer_type = TYPE_MAIN_VARIANT (outer_type);
diff --git a/gcc/testsuite/gcc.dg/pr104506.c b/gcc/testsuite/gcc.dg/pr104506.c
new file mode 100644
index 0000000..79cec1a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr104506.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double x;
+/* { dg-message "note: previous declaration" "previous declaration" { target
*-*
+ * -* } .-1 } */
+
+void foo (void)
+{
+ x;
+}
+
+int x; /* { dg-error "conflicting types" } */
+
