Re: [PATCH] Fix -Wmisleading indentation false-positive for do-while statement

[David Malcolm <dmalcolm at redhat dot com>]

On Tue, 2015-12-22 at 12:33 -0500, Patrick Palka wrote:
> We are emitting a bogus warning for the code
> 
>   do foo (0); while (flagA);
>               ^--- NEXT
>      ^------------ BODY
>   ^--------------- GUARD
> 
> In general I don't think we can get any useful indentation warning out
> of a do-while statement, so this patch makes it so that we just skip
> them.
> 
> Is this OK to commit after testing?

It looks like this is PR c++/69029.  FWIW, I agree with your rationale -
though perhaps we should instead update the frontends to not even call
into c-indentation.c for do-while statements?

> gcc/c-family/ChangeLog:
> 
> 	* c-indentation.c (should_warn_for_misleading_indentation):
> 	Don't warn about do-while statements.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* c-c++-common/Wisleading-indentation.c: Augment test.
> ---
>  gcc/c-family/c-indentation.c                         | 6 ++++++
>  gcc/testsuite/c-c++-common/Wmisleading-indentation.c | 2 ++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/gcc/c-family/c-indentation.c b/gcc/c-family/c-indentation.c
> index 638a9cf..1cbaab7 100644
> --- a/gcc/c-family/c-indentation.c
> +++ b/gcc/c-family/c-indentation.c
> @@ -202,6 +202,12 @@ should_warn_for_misleading_indentation (const token_indent_info &guard_tinfo,
>    if (line_table->seen_line_directive)
>      return false;
>  
> +  /* We can't usefully warn about do-while statements since the bodies of these
> +     statements are always explicitly delimited at both ends, so control flow is
> +     quite obvious.  */
> +  if (guard_tinfo.keyword == RID_DO)
> +    return false;
> +
>    /* If the token following the body is a close brace or an "else"
>       then while indentation may be sloppy, there is not much ambiguity
>       about control flow, e.g.
> diff --git a/gcc/testsuite/c-c++-common/Wmisleading-indentation.c b/gcc/testsuite/c-c++-common/Wmisleading-indentation.c
> index a3f5acd..72c21a0 100644
> --- a/gcc/testsuite/c-c++-common/Wmisleading-indentation.c
> +++ b/gcc/testsuite/c-c++-common/Wmisleading-indentation.c
> @@ -890,4 +890,6 @@ fn_39 (void)
>         i < 10;
>         i++);
>    foo (i);
> +
> +  do foo (0); while (flagA);
>  }