On Wed, 2016-08-24 at 19:43 +0200, Marek Polacek wrote:
> This patch adds a fixit hint to -Wlogical-not-parentheses. When the
> LHS
> has a location, it prints:
>
> z.c: In function ‘int foo(int, int)’:
> z.c:12:11: warning: logical not is only applied to the left hand side
> of comparison [-Wlogical-not-parentheses]
> r += !a == b;
> ^~
> z.c:12:8: note: add parentheses around left hand side expression to
> silence this warning
> r += !a == b;
> ^~
> ( )
>
> Bootstrapped/regtested on x86_64-linux and ppc64le-redhat-linux, ok
> for trunk?
Thanks for writing new fix-it hints.
Can you split this up into two fix-its, one for each parenthesis, at
the appropriate locations? A single rich_location (and thus
diagnostic) can contain up to 3 fix-it hints at the moment. My hope
is that an IDE could, in theory, apply them; right now, the fixit is
effectively saying to make this change:
- r += !a == b;
+ r += ( )!a == b;
whereas presumably it should be making this change:
- r += !a == b;
+ r += (!a) == b;
You should be able to access the source end-point of the expression
via:
get_range_from_loc (line_table, loc).m_finish
Also, when writing testcases that involve -fdiagnostics-show-caret,
please use identifier names that are longer than one character: this
makes it easier to verify that we're using the correct ranges.
> 2016-08-24 Marek Polacek <pola...@redhat.com>
>
> * c-common.c (warn_logical_not_parentheses): Print fixit hints.
> * c-common.h (warn_logical_not_parentheses): Update
> declaration.
>
> * c-typeck.c (parser_build_binary_op): Pass LHS to
> warn_logical_not_parentheses.
>
> * parser.c (cp_parser_binary_expression): Pass LHS to
> warn_logical_not_parentheses.
>
> * c-c++-common/Wlogical-not-parentheses-2.c: New test.
>
> diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
> index 3feb910..a445df1 100644
> --- gcc/c-family/c-common.c
> +++ gcc/c-family/c-common.c
> @@ -1485,7 +1485,7 @@ warn_tautological_cmp (location_t loc, enum
> tree_code code, tree lhs, tree rhs)
>
> void
> warn_logical_not_parentheses (location_t location, enum tree_code
> code,
> - tree rhs)
> + tree lhs, tree rhs)
> {
> if (TREE_CODE_CLASS (code) != tcc_comparison
> || TREE_TYPE (rhs) == NULL_TREE
> @@ -1498,9 +1498,16 @@ warn_logical_not_parentheses (location_t
> location, enum tree_code code,
> && integer_zerop (rhs))
> return;
>
> - warning_at (location, OPT_Wlogical_not_parentheses,
> - "logical not is only applied to the left hand side of
> "
> - "comparison");
> + if (warning_at (location, OPT_Wlogical_not_parentheses,
> + "logical not is only applied to the left hand side
> of "
> + "comparison")
> + && EXPR_HAS_LOCATION (lhs))
> + {
> + rich_location richloc (line_table, EXPR_LOCATION (lhs));
> + richloc.add_fixit_insert (EXPR_LOCATION (lhs), "( )");
> + inform_at_rich_loc (&richloc, "add parentheses around left
> hand side "
> + "expression to silence this warning");
> + }
> }
>
> /* Warn if EXP contains any computations whose results are not used.
> diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
> index bc22baa..42ce969 100644
> --- gcc/c-family/c-common.h
> +++ gcc/c-family/c-common.h
> @@ -847,7 +847,8 @@ extern void overflow_warning (location_t, tree);
> extern bool warn_if_unused_value (const_tree, location_t);
> extern void warn_logical_operator (location_t, enum tree_code, tree,
> enum tree_code, tree, enum
> tree_code, tree);
> -extern void warn_logical_not_parentheses (location_t, enum
> tree_code, tree);
> +extern void warn_logical_not_parentheses (location_t, enum
> tree_code, tree,
> + tree);
> extern void warn_tautological_cmp (location_t, enum tree_code, tree,
> tree);
> extern void check_main_parameter_types (tree decl);
> extern bool c_determine_visibility (tree);
> diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
> index bc8728a..2f8d611 100644
> --- gcc/c/c-typeck.c
> +++ gcc/c/c-typeck.c
> @@ -3696,7 +3696,7 @@ parser_build_binary_op (location_t location,
> enum tree_code code,
> while (1);
> }
> if (TREE_CODE (TREE_TYPE (t)) != BOOLEAN_TYPE)
> - warn_logical_not_parentheses (location, code, arg2.value);
> + warn_logical_not_parentheses (location, code, arg1.value,
> arg2.value);
> }
>
> /* Warn about comparisons against string literals, with the
> exception
> diff --git gcc/cp/parser.c gcc/cp/parser.c
> index 690e928..d54cf8a 100644
> --- gcc/cp/parser.c
> +++ gcc/cp/parser.c
> @@ -8922,7 +8922,7 @@ cp_parser_binary_expression (cp_parser* parser,
> bool cast_p,
> || TREE_TYPE (current.lhs) == NULL_TREE
> || TREE_CODE (TREE_TYPE (current.lhs)) !=
> BOOLEAN_TYPE))
> warn_logical_not_parentheses (current.loc,
> current.tree_type,
> - maybe_constant_value (rhs));
> + current.lhs,
> maybe_constant_value (rhs));
>
> overload = NULL;
>
> diff --git gcc/testsuite/c-c++-common/Wlogical-not-parentheses-2.c
> gcc/testsuite/c-c++-common/Wlogical-not-parentheses-2.c
> index e69de29..c5c2aac 100644
> --- gcc/testsuite/c-c++-common/Wlogical-not-parentheses-2.c
> +++ gcc/testsuite/c-c++-common/Wlogical-not-parentheses-2.c
> @@ -0,0 +1,20 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Wlogical-not-parentheses -fdiagnostics-show-caret"
> } */
> +
> + /* Test fixit hints. */
> +
> +int
> +foo (int a, int b)
> +{
> + int r = 0;
> + r += (!a) == b;
> + r += !a == b; /* { dg-warning "logical not is only applied" } */
> +/* { dg-begin-multiline-output "" }
> + r += !a == b;
> + ^~
> + r += !a == b;
> + ^~
> + ( )
> + { dg-end-multiline-output "" } */
> + return r;
> +}
>
> Marek
