Re: [PATCH 1/2] Fix new -Wparentheses warnings encountered during bootstrap

[Bernd Schmidt <bschmidt@redhat.com>]

On 03/31/2016 10:53 PM, Patrick Palka wrote:
> This patch fixes the new -Wparentheses warnings (implemented by the
> subsequent patch) that are encountered during bootstrap:
>
> /home/patrick/code/gcc/gcc/omp-low.c: In function ‘void scan_sharing_clauses(tree, omp_context*, bool)’:
> /home/patrick/code/gcc/gcc/omp-low.c:2381:6: error: suggest explicit braces to avoid ambiguous ‘else’ [-Werror=parentheses]
>     if (scan_array_reductions)
>        ^
> /home/patrick/code/gcc/gcc/gimplify.c: In function ‘gimple* gimplify_omp_ordered(tree, gimple_seq)’:
> /home/patrick/code/gcc/gcc/gimplify.c:9880:6: error: suggest explicit braces to avoid ambiguous ‘else’ [-Werror=parentheses]
>     if (gimplify_omp_ctxp)
>        ^
> In file included from /home/patrick/code/gcc/gcc/cp/optimize.c:25:0:
> /home/patrick/code/gcc/gcc/cp/optimize.c: In function ‘void populate_clone_array(tree, tree_node**)’:
> /home/patrick/code/gcc/gcc/cp/cp-tree.h:2529:6: error: suggest explicit braces to avoid ambiguous ‘else’ [-Werror=parentheses]
>     if (TREE_CODE (FN) == FUNCTION_DECL   \
>        ^
> /home/patrick/code/gcc/gcc/cp/optimize.c:222:3: note: in expansion of macro ‘FOR_EACH_CLONE’
>     FOR_EACH_CLONE (clone, fn)
>     ^~~~~~~~~~~~~~
> /home/patrick/code/gcc/gcc/fortran/openmp.c: In function ‘gfc_omp_udr* gfc_find_omp_udr(gfc_namespace*, const char*, gfc_typespec*)’:
> /home/patrick/code/gcc/gcc/fortran/openmp.c:177:10: error: suggest explicit braces to avoid ambiguous ‘else’ [-Werror=parentheses]
>         if (st != NULL)
>            ^
>
> In each case I think the warning is harmless since the indentation of
> the code in question corresponds to how the "else" is actually parsed
> so I fixed each case simply by enclosing the entire body of the outer
> "if" in braces.
>
> The FOR_EACH_CLONE change resolves the cp/optimize.c warning.  It
> adjusts the layout of the macro from
>
>    if (p)
>      for (...)
>
> to
>
>    if (!p)
>      ;
>    else for (...)
>
> so that an "else" encountered in the body of the for-statement can no
> longer possibly bind to the outer "if (p)" conditional.
>
> Is this OK to commit after bootstrap + regtesting?

I think this is OK, now or in stage1 depending on whether the warning 
improvements go in now or later.

I see a patch for the C++ side fixing the warning, do you also intend to 
do C?


Bernd