Re: [PATCH] PR c/71171: Fix uninitialized source_range in c_parser_postfix_expression

[Jeff Law <law at redhat dot com>]

On 05/18/2016 07:08 PM, David Malcolm wrote:
> PR c/71171 reports yet another instance of the src_range of a
> c_expr being used without initialization.  Investigation shows
> that this was due to error-handling, where the "value" field of
> a c_expr is set to error_mark_node without touching the
> src_range, leading to complaints from valgrind.
>
> This seems to be a common mistake, so this patch introduces a
> new method, c_expr::set_error, which sets the value to
> error_mark_node whilst initializing the src_range to
> UNKNOWN_LOCATION.
>
> This fixes the valgrind issue seen in PR c/71171, along with various
> similar issues seen when running the testsuite using the checker
> patch I posted here:
>   https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00887.html
> (this checker still doesn't fully work yet, but it seems to be good
> for easily detecting these issues without needing Valgrind).
>
> Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.
>
> OK for trunk and for gcc-6-branch?
>
> gcc/c/ChangeLog:
> 	PR c/71171
> 	* c-parser.c (c_parser_generic_selection): Use c_expr::set_error
> 	in error-handling.
> 	(c_parser_postfix_expression): Likewise.
> 	* c-tree.h (c_expr::set_error): New method.
> 	* c-typeck.c (parser_build_binary_op): In error-handling, ensure
> 	that result's range is initialized.
OK.
jeff