From 823685221de986afb729910a6f2237f07a377f17 Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Wed, 1 Sep 2021 08:38:39 +0100 Subject: C: PR c/79412: Poison decls with error_mark_node after type mismatch This patch fixes an ICE during error-recovery regression in the C front-end. The symptom is that the middle-end's sanity checking assertions fail during gimplification when being asked to increment an array, which is non-sense. The issue is that the C-front end has detected the type mismatch and reported an error to the user, but hasn't provided any indication of this to the middle-end, simply passing bogus trees that the optimizers recognize as invalid. This appears to be a frequently reported ICE with 94730, 94731, 101036 and 101365 all marked as duplicates. I believe the correct (polite) fix is to mark the mismatched types as problematic/dubious in the front-end, when the error is spotted, so that the middle-end has a heads-up and can be a little more forgiving. This patch to c-decl.c's duplicate_decls sets (both) mismatched types to error_mark_node if they are significantly different, and we've issued an error message. Alas, this is too punitive for FUNCTION_DECLs where we store return types, parameter lists, parameter types and attributes in the type, but fortunately the middle-end is already more cautious about trusting possibly suspect function types. This fix required one minor change to the testsuite, typedef-var-2.c where after conflicting type definitions, we now no longer assume that the (first or) second definition is the correct one. This change only affects the behaviour after seen_error(), so should be relatively safe. 2021-09-01 Roger Sayle Joseph Myers gcc/c/ChangeLog PR c/79412 * c-decl.c (duplicate_decls): On significant mismatches, mark the types of both (non-function) decls as error_mark_node, so that the middle-end can see the code is malformed. (free_attr_access_data): Don't process if the type has been set to error_mark_node. gcc/testsuite/ChangeLog PR c/79412 * gcc.dg/pr79412.c: New test case. * gcc.dg/typedef-var-2.c: Update expeted errors. --- gcc/testsuite/gcc.dg/pr79412.c | 9 +++++++++ gcc/testsuite/gcc.dg/typedef-var-2.c | 5 +++-- 2 files changed, 12 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr79412.c (limited to 'gcc/testsuite/gcc.dg') diff --git a/gcc/testsuite/gcc.dg/pr79412.c b/gcc/testsuite/gcc.dg/pr79412.c new file mode 100644 index 0000000..b60d5e1 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr79412.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ +int a; +/* { dg-message "note: previous declaration" "previous declaration" { target *-*-* } .-1 } */ +void fn1 () +{ + a++; +} +int a[] = {2}; /* { dg-error "conflicting types" } */ diff --git a/gcc/testsuite/gcc.dg/typedef-var-2.c b/gcc/testsuite/gcc.dg/typedef-var-2.c index 716d29c..bc119a0 100644 --- a/gcc/testsuite/gcc.dg/typedef-var-2.c +++ b/gcc/testsuite/gcc.dg/typedef-var-2.c @@ -4,12 +4,13 @@ int f (void) { extern float v; - +/* { dg-message "note: previous declaration" "previous declaration" { target *-*-* } .-1 } */ return (v > 0.0f); } extern int t; +/* { dg-message "note: previous declaration" "previous declaration" { target *-*-* } .-1 } */ typedef float t; /* { dg-error "redeclared as different kind of symbol" } */ -t v = 4.5f; +t v = 4.5f; /* { dg-error "conflicting types" } */ -- cgit v1.1