From 65371066d8967560e3508af4a804e0ddb90acee7 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 24 Jun 2021 12:22:14 +0200 Subject: [PATCH] stor-layout: Avoid DECL_BIT_FIELD_REPRESENTATIVE with NULL TREE_TYPE [PR101172] finish_bitfield_representative has an early out if the field after a bitfield has error_mark_node type, but that early out leads to TREE_TYPE of the DECL_BIT_FIELD_REPRESENTATIVE being NULL, which breaks assumptions on code that uses the DECL_BIT_FIELD_REPRESENTATIVE during error-recovery. The following patch instead sets TREE_TYPE of the representative to error_mark_node, something the users can deal with better. At this point the representative can be set as DECL_BIT_FIELD_REPRESENTATIVE for multiple bitfields, so making sure that we clear the DECL_BIT_FIELD_REPRESENTATIVE instead would be harder (but doable, e.g. with the error_mark_node TREE_TYPE set by this patch set some flag in the caller and if the flag is there, walk all the fields once again and clear all DECL_BIT_FIELD_REPRESENTATIVE that have error_mark_node TREE_TYPE). 2021-06-24 Jakub Jelinek PR middle-end/101172 * stor-layout.c (finish_bitfield_representative): If nextf has error_mark_node type, set repr type to error_mark_node too. * gcc.dg/pr101172.c: New test. --- gcc/stor-layout.c | 5 ++++- gcc/testsuite/gcc.dg/pr101172.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr101172.c diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c index 9f850c3..242452f 100644 --- a/gcc/stor-layout.c +++ b/gcc/stor-layout.c @@ -2086,7 +2086,10 @@ finish_bitfield_representative (tree repr, tree field) /* If there was an error, the field may be not laid out correctly. Don't bother to do anything. */ if (TREE_TYPE (nextf) == error_mark_node) - return; + { + TREE_TYPE (repr) = error_mark_node; + return; + } maxsize = size_diffop (DECL_FIELD_OFFSET (nextf), DECL_FIELD_OFFSET (repr)); if (tree_fits_uhwi_p (maxsize)) diff --git a/gcc/testsuite/gcc.dg/pr101172.c b/gcc/testsuite/gcc.dg/pr101172.c new file mode 100644 index 0000000..b9d098b --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr101172.c @@ -0,0 +1,20 @@ +/* PR middle-end/101172 */ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +union U +{ + int a[3]; + struct + { + int a : 3; + struct this_struct var; /* { dg-error "field 'var' has incomplete type" } */ + } b; +}; + +const union U hello = {.a = {1, 2, 3}}; + +void foo() +{ + int x = hello.b.a; +} -- 2.7.4