Re: [PATCH] C FE: implement fix-it hint for -Wmissing-braces

[Jeff Law]

On 11/11/2016 06:30 PM, David Malcolm wrote:

This patch implements fix-it hints to -Wmissing-braces, showing where to
add braces.

For example:

  $ cat test.c
  int arr_2_3_2[2][3][2] =
    { 0, 1, 2, 3, 4, 5,
      6, 7, 8, 9, 10, 11};

  $ ./xgcc -B. -c test.c -Wall -fdiagnostics-generate-patch
  test.c:2:3: warning: missing braces around initializer [-Wmissing-braces]
     { 0, 1, 2, 3, 4, 5,
     ^
       {
       {   } {   } {   }
                       }
       6, 7, 8, 9, 10, 11};
       {
       {   } {   } {     }
                         }
  --- test.c
  +++ test.c
  @@ -1,3 +1,3 @@
   int arr_2_3_2[2][3][2] =
  -  { 0, 1, 2, 3, 4, 5,
  -    6, 7, 8, 9, 10, 11};
  +  { {{0, 1}, {2, 3}, {4, 5}},
  +    {{6, 7}, {8, 9}, {10, 11}}};

Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu; adds
29 PASS results to gcc.sum.

OK for trunk?

gcc/c/ChangeLog:
        * c-parser.c (c_parser_declaration_or_fndef): Create a
        rich_location at init_loc and parse it to start_init.
        (last_init_list_comma): New global.
        (c_parser_braced_init): Update last_init_list_comma when parsing
        commas.  Pass it to pop_init_level.  Pass location of closing
        brace to pop_init_level.
        (c_parser_postfix_expression_after_paren_type): Create a
        rich_location at type_loc and parse it to start_init.
        (c_parser_omp_declare_reduction): Likewise for loc.
        * c-tree.h (start_init): Add rich_location * param.
        (pop_init_level): Add location_t param.
        * c-typeck.c (struct initializer_stack): Add field
        "missing_brace_richloc".
        (start_init): Add richloc param, use it to initialize
        the stack node's missing_brace_richloc.
        (last_init_list_comma): New decl.
        (finish_implicit_inits): Pass last_init_list_comma to
        pop_init_level.
        (push_init_level): When finding missing open braces, add fix-it
        hints to the richloc.
        (pop_init_level): Add "insert_before" param and pass it
        when calling pop_init_level.  Add fixits about missing
        close braces to any richloc.  Use the richloc for the
        -Wmissing-braces warning.
        (set_designator): Pass last_init_list_comma to pop_init_level.
        (process_init_element): Likewise.

gcc/testsuite/ChangeLog:
        * gcc.dg/Wmissing-braces-fixits.c: New test case.

I'm a bit unsure about how useful this is in practice.  But OK.

jeff