On 09/29/16 22:38, Jason Merrill wrote:
> On Thu, Sep 29, 2016 at 3:58 PM, Bernd Edlinger
> <[email protected]> wrote:
>> Unfortunately, without that exception there is a false positive:
>>
>> In file included from ../../gcc-trunk/gcc/ada/gcc-interface/decl.c:30:0:
>> ../../gcc-trunk/gcc/ada/gcc-interface/decl.c: In function 'int
>> adjust_packed(tree, tree, int)':
>> ../../gcc-trunk/gcc/tree.h:1874:22: error: << on signed integer in
>> boolean context [-Werror=int-in-bool-context]
>> ? ((unsigned)1) << ((NODE)->type_common.align - 1) : 0)
>> ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Ah, this issue again: the shift isn't in boolean context, it's in
> integer context. I think we want to be a lot more conservative about
> these warnings in the arms of a COND_EXPR. In fact, I think the
> entire
>
> /* Distribute the conversion into the arms of a COND_EXPR. */
>
> section is wrong now that we're doing delayed folding.
>
Could you take care of this ?
For the warning, I think I can suppress it just while
the recursing into the condition arms.
As in this updated patch.
Is it OK?
Bernd.
gcc:
2016-09-29 Bernd Edlinger <[email protected]>
* doc/invoke.texi: Update -Wint-in-bool-context.
c-family:
2016-09-29 Bernd Edlinger <[email protected]>
* c-common.c (c_common_truthvalue_conversion): Warn for suspicious
left shift in boolean context.
cp:
2016-09-29 Bernd Edlinger <[email protected]>
* parser.c (cp_parser_condition): Fix a warning.
testsuite:
2016-09-29 Bernd Edlinger <[email protected]>
* c-c++-common/Wint-in-bool-context.c: Update test.
Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c (revision 240571)
+++ gcc/c-family/c-common.c (working copy)
@@ -4655,6 +4655,11 @@ c_common_truthvalue_conversion (location_t locatio
return c_common_truthvalue_conversion (location,
TREE_OPERAND (expr, 0));
+ case LSHIFT_EXPR:
+ warning_at (EXPR_LOCATION (expr), OPT_Wint_in_bool_context,
+ "<< in boolean context, did you mean '<' ?");
+ break;
+
case COND_EXPR:
if (warn_int_in_bool_context
&& !from_macro_definition_at (EXPR_LOCATION (expr)))
@@ -4676,6 +4681,8 @@ c_common_truthvalue_conversion (location_t locatio
{
tree op1 = TREE_OPERAND (expr, 1);
tree op2 = TREE_OPERAND (expr, 2);
+ int w = warn_int_in_bool_context;
+ warn_int_in_bool_context = 0;
/* In C++ one of the arms might have void type if it is throw. */
if (!VOID_TYPE_P (TREE_TYPE (op1)))
op1 = c_common_truthvalue_conversion (location, op1);
@@ -4683,10 +4690,13 @@ c_common_truthvalue_conversion (location_t locatio
op2 = c_common_truthvalue_conversion (location, op2);
expr = fold_build3_loc (location, COND_EXPR, truthvalue_type_node,
TREE_OPERAND (expr, 0), op1, op2);
+ warn_int_in_bool_context = w;
goto ret;
}
else
{
+ int w = warn_int_in_bool_context;
+ warn_int_in_bool_context = 0;
/* Folding will happen later for C. */
expr = build3 (COND_EXPR, truthvalue_type_node,
TREE_OPERAND (expr, 0),
@@ -4694,6 +4704,7 @@ c_common_truthvalue_conversion (location_t locatio
TREE_OPERAND (expr, 1)),
c_common_truthvalue_conversion (location,
TREE_OPERAND (expr, 2)));
+ warn_int_in_bool_context = w;
goto ret;
}
Index: gcc/cp/parser.c
===================================================================
--- gcc/cp/parser.c (revision 240571)
+++ gcc/cp/parser.c (working copy)
@@ -11244,7 +11244,7 @@ cp_parser_condition (cp_parser* parser)
{
tree pushed_scope;
bool non_constant_p;
- bool flags = LOOKUP_ONLYCONVERTING;
+ int flags = LOOKUP_ONLYCONVERTING;
/* Create the declaration. */
decl = start_decl (declarator, &type_specifiers,
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 240571)
+++ gcc/doc/invoke.texi (working copy)
@@ -6028,7 +6028,8 @@ of the C++ standard.
@opindex Wno-int-in-bool-context
Warn for suspicious use of integer values where boolean values are expected,
such as conditional expressions (?:) using non-boolean integer constants in
-boolean context, like @code{if (a <= b ? 2 : 3)}.
+boolean context, like @code{if (a <= b ? 2 : 3)}. Or left shifting in
+boolean context, like @code{for (a = 0; 1 << a; a++);}.
This warning is enabled by @option{-Wall}.
@item -Wno-int-to-pointer-cast
Index: gcc/testsuite/c-c++-common/Wint-in-bool-context.c
===================================================================
--- gcc/testsuite/c-c++-common/Wint-in-bool-context.c (revision 240571)
+++ gcc/testsuite/c-c++-common/Wint-in-bool-context.c (working copy)
@@ -25,5 +25,7 @@ int foo (int a, int b)
if (b ? 1+1 : 1) /* { dg-warning "boolean context" } */
return 7;
+ for (a = 0; 1 << a; a++); /* { dg-warning "boolean context" } */
+
return 0;
}
