[C++ Patch/RFC] PR 54194
Paolo Carlini
paolo.carlini@oracle.com
Mon Oct 8 10:03:00 GMT 2012
Hi,
in this PR submitter points out that in the -Wparentheses warning, for, eg,
char in[4]={0}, out[6];
out[1] = in[1] & 0x0F | ((in[3] & 0x3C) << 2);
warning: suggest parentheses around arithmetic in operand of ‘|’
[-Wparentheses]
the caret points to end of the expression, ie the final closing
parenthesis, which is rather misleading, because the problem is actually
in the first operand of '|'. Ideally I guess one would like to somehow
point to that first operand, but our infrastructure (shared with the C
front-end, at the moment) isn't really ready to do that, and probably we
would like to use a range (more than a caret) below the whole first
operand (the problem isn't really with & per se). Considering also what
we are already doing elsewhere, it seems to me that a straightforward
and good improvement is obtained by passing to warn_about_parentheses
the location of the outer operand (together with its code), as per the
attached patchlet: then in the example the caret points to the actual
'|' operator mentioned in the error message. Post 4.8.0 we can imagine
further improvements...
What do you think?
Thanks,
Paolo.
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-------------- next part --------------
Index: cp/typeck.c
===================================================================
--- cp/typeck.c (revision 192130)
+++ cp/typeck.c (working copy)
@@ -3630,7 +3630,8 @@ build_x_binary_op (location_t loc, enum tree_code
&& !error_operand_p (arg2)
&& (code != LSHIFT_EXPR
|| !CLASS_TYPE_P (TREE_TYPE (arg1))))
- warn_about_parentheses (code, arg1_code, orig_arg1, arg2_code, orig_arg2);
+ warn_about_parentheses (loc, code, arg1_code, orig_arg1,
+ arg2_code, orig_arg2);
if (processing_template_decl && expr != error_mark_node)
return build_min_non_dep (code, expr, orig_arg1, orig_arg2);
Index: c-family/c-common.c
===================================================================
--- c-family/c-common.c (revision 192130)
+++ c-family/c-common.c (working copy)
@@ -10428,7 +10428,7 @@ warn_array_subscript_with_type_char (tree index)
was enclosed in parentheses. */
void
-warn_about_parentheses (enum tree_code code,
+warn_about_parentheses (location_t loc, enum tree_code code,
enum tree_code code_left, tree arg_left,
enum tree_code code_right, tree arg_right)
{
@@ -10449,26 +10449,26 @@ void
{
case LSHIFT_EXPR:
if (code_left == PLUS_EXPR || code_right == PLUS_EXPR)
- warning (OPT_Wparentheses,
- "suggest parentheses around %<+%> inside %<<<%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around %<+%> inside %<<<%>");
else if (code_left == MINUS_EXPR || code_right == MINUS_EXPR)
- warning (OPT_Wparentheses,
- "suggest parentheses around %<-%> inside %<<<%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around %<-%> inside %<<<%>");
return;
case RSHIFT_EXPR:
if (code_left == PLUS_EXPR || code_right == PLUS_EXPR)
- warning (OPT_Wparentheses,
- "suggest parentheses around %<+%> inside %<>>%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around %<+%> inside %<>>%>");
else if (code_left == MINUS_EXPR || code_right == MINUS_EXPR)
- warning (OPT_Wparentheses,
- "suggest parentheses around %<-%> inside %<>>%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around %<-%> inside %<>>%>");
return;
case TRUTH_ORIF_EXPR:
if (code_left == TRUTH_ANDIF_EXPR || code_right == TRUTH_ANDIF_EXPR)
- warning (OPT_Wparentheses,
- "suggest parentheses around %<&&%> within %<||%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around %<&&%> within %<||%>");
return;
case BIT_IOR_EXPR:
@@ -10476,18 +10476,19 @@ void
|| code_left == PLUS_EXPR || code_left == MINUS_EXPR
|| code_right == BIT_AND_EXPR || code_right == BIT_XOR_EXPR
|| code_right == PLUS_EXPR || code_right == MINUS_EXPR)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around arithmetic in operand of %<|%>");
/* Check cases like x|y==z */
else if (TREE_CODE_CLASS (code_left) == tcc_comparison
|| TREE_CODE_CLASS (code_right) == tcc_comparison)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<|%>");
/* Check cases like !x | y */
else if (code_left == TRUTH_NOT_EXPR
&& !APPEARS_TO_BE_BOOLEAN_EXPR_P (code_right, arg_right))
- warning (OPT_Wparentheses, "suggest parentheses around operand of "
- "%<!%> or change %<|%> to %<||%> or %<!%> to %<~%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around operand of "
+ "%<!%> or change %<|%> to %<||%> or %<!%> to %<~%>");
return;
case BIT_XOR_EXPR:
@@ -10495,44 +10496,45 @@ void
|| code_left == PLUS_EXPR || code_left == MINUS_EXPR
|| code_right == BIT_AND_EXPR
|| code_right == PLUS_EXPR || code_right == MINUS_EXPR)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around arithmetic in operand of %<^%>");
/* Check cases like x^y==z */
else if (TREE_CODE_CLASS (code_left) == tcc_comparison
|| TREE_CODE_CLASS (code_right) == tcc_comparison)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<^%>");
return;
case BIT_AND_EXPR:
if (code_left == PLUS_EXPR || code_right == PLUS_EXPR)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around %<+%> in operand of %<&%>");
else if (code_left == MINUS_EXPR || code_right == MINUS_EXPR)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around %<-%> in operand of %<&%>");
/* Check cases like x&y==z */
else if (TREE_CODE_CLASS (code_left) == tcc_comparison
|| TREE_CODE_CLASS (code_right) == tcc_comparison)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<&%>");
/* Check cases like !x & y */
else if (code_left == TRUTH_NOT_EXPR
&& !APPEARS_TO_BE_BOOLEAN_EXPR_P (code_right, arg_right))
- warning (OPT_Wparentheses, "suggest parentheses around operand of "
- "%<!%> or change %<&%> to %<&&%> or %<!%> to %<~%>");
+ warning_at (loc, OPT_Wparentheses,
+ "suggest parentheses around operand of "
+ "%<!%> or change %<&%> to %<&&%> or %<!%> to %<~%>");
return;
case EQ_EXPR:
if (TREE_CODE_CLASS (code_left) == tcc_comparison
|| TREE_CODE_CLASS (code_right) == tcc_comparison)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<==%>");
return;
case NE_EXPR:
if (TREE_CODE_CLASS (code_left) == tcc_comparison
|| TREE_CODE_CLASS (code_right) == tcc_comparison)
- warning (OPT_Wparentheses,
+ warning_at (loc, OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<!=%>");
return;
@@ -10544,8 +10546,9 @@ void
|| (TREE_CODE_CLASS (code_right) == tcc_comparison
&& code_right != NE_EXPR && code_right != EQ_EXPR
&& INTEGRAL_TYPE_P (TREE_TYPE (arg_right)))))
- warning (OPT_Wparentheses, "comparisons like %<X<=Y<=Z%> do not "
- "have their mathematical meaning");
+ warning_at (loc, OPT_Wparentheses,
+ "comparisons like %<X<=Y<=Z%> do not "
+ "have their mathematical meaning");
return;
}
#undef NOT_A_BOOLEAN_EXPR_P
Index: c-family/c-common.h
===================================================================
--- c-family/c-common.h (revision 192130)
+++ c-family/c-common.h (working copy)
@@ -988,7 +988,8 @@ extern tree builtin_type_for_size (int, bool);
extern void c_common_mark_addressable_vec (tree);
extern void warn_array_subscript_with_type_char (tree);
-extern void warn_about_parentheses (enum tree_code,
+extern void warn_about_parentheses (location_t,
+ enum tree_code,
enum tree_code, tree,
enum tree_code, tree);
extern void warn_for_unused_label (tree label);
Index: c/c-typeck.c
===================================================================
--- c/c-typeck.c (revision 192130)
+++ c/c-typeck.c (working copy)
@@ -3261,7 +3261,8 @@ parser_build_binary_op (location_t location, enum
/* Check for cases such as x+y<<z which users are likely
to misinterpret. */
if (warn_parentheses)
- warn_about_parentheses (code, code1, arg1.value, code2, arg2.value);
+ warn_about_parentheses (input_location, code,
+ code1, arg1.value, code2, arg2.value);
if (warn_logical_op)
warn_logical_operator (input_location, code, TREE_TYPE (result.value),
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