/* Implement -Wparentheses for the unexpected C precedence rules, to
cover cases like x + y << z which readers are likely to
misinterpret. We have seen an expression in which CODE is a binary
- operator used to combine expressions headed by CODE_LEFT and
- CODE_RIGHT. CODE_LEFT and CODE_RIGHT may be ERROR_MARK, which
- means that that side of the expression was not formed using a
- binary operator, or it was enclosed in parentheses. */
+ operator used to combine expressions ARG_LEFT and ARG_RIGHT, which
+ before folding had CODE_LEFT and CODE_RIGHT. CODE_LEFT and
+ CODE_RIGHT may be ERROR_MARK, which means that that side of the
+ expression was not formed using a binary or unary operator, or it
+ was enclosed in parentheses. */
void
-warn_about_parentheses (enum tree_code code, enum tree_code code_left,
- enum tree_code code_right)
+warn_about_parentheses (enum tree_code code,
+ enum tree_code code_left, tree ARG_UNUSED (arg_left),
+ enum tree_code code_right, tree arg_right)
{
if (!warn_parentheses)
return;
- if (code == LSHIFT_EXPR || code == RSHIFT_EXPR)
+ /* This macro tests that the expression ARG with original tree code
+ CODE appears to be a boolean expression. or the result of folding a
+ boolean expression. */
+#define APPEARS_TO_BE_BOOLEAN_EXPR_P(CODE, ARG) \
+ (truth_value_p (TREE_CODE (ARG)) \
+ || TREE_CODE (TREE_TYPE (ARG)) == BOOLEAN_TYPE \
+ /* Folding may create 0 or 1 integers from other expressions. */ \
+ || ((CODE) != INTEGER_CST \
+ && (integer_onep (ARG) || integer_zerop (ARG))))
+
+ switch (code)
{
- if (code_left == PLUS_EXPR || code_left == MINUS_EXPR
- || code_right == PLUS_EXPR || code_right == MINUS_EXPR)
+ case LSHIFT_EXPR:
+ if (code_left == PLUS_EXPR || code_right == PLUS_EXPR)
warning (OPT_Wparentheses,
- "suggest parentheses around + or - inside shift");
- }
+ "suggest parentheses around %<+%> inside %<<<%>");
+ else if (code_left == MINUS_EXPR || code_right == MINUS_EXPR)
+ warning (OPT_Wparentheses,
+ "suggest parentheses around %<-%> inside %<<<%>");
+ return;
- if (code == TRUTH_ORIF_EXPR)
- {
- if (code_left == TRUTH_ANDIF_EXPR
- || code_right == TRUTH_ANDIF_EXPR)
+ case RSHIFT_EXPR:
+ if (code_left == PLUS_EXPR || code_right == PLUS_EXPR)
warning (OPT_Wparentheses,
- "suggest parentheses around && within ||");
- }
+ "suggest parentheses around %<+%> inside %<>>%>");
+ else if (code_left == MINUS_EXPR || code_right == MINUS_EXPR)
+ warning (OPT_Wparentheses,
+ "suggest parentheses around %<-%> inside %<>>%>");
+ return;
- if (code == BIT_IOR_EXPR)
- {
+ case TRUTH_ORIF_EXPR:
+ if (code_left == TRUTH_ANDIF_EXPR || code_right == TRUTH_ANDIF_EXPR)
+ warning (OPT_Wparentheses,
+ "suggest parentheses around %<&&%> within %<||%>");
+ return;
+
+ case BIT_IOR_EXPR:
if (code_left == BIT_AND_EXPR || code_left == BIT_XOR_EXPR
|| 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,
- "suggest parentheses around arithmetic in operand of |");
+ "suggest parentheses around arithmetic in operand of %<|%>");
/* Check cases like x|y==z */
- if (TREE_CODE_CLASS (code_left) == tcc_comparison
- || TREE_CODE_CLASS (code_right) == tcc_comparison)
+ else if (TREE_CODE_CLASS (code_left) == tcc_comparison
+ || TREE_CODE_CLASS (code_right) == tcc_comparison)
warning (OPT_Wparentheses,
- "suggest parentheses around comparison in operand of |");
- }
+ "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 %<~%>");
+ return;
- if (code == BIT_XOR_EXPR)
- {
+ case BIT_XOR_EXPR:
if (code_left == BIT_AND_EXPR
|| code_left == PLUS_EXPR || code_left == MINUS_EXPR
|| code_right == BIT_AND_EXPR
|| code_right == PLUS_EXPR || code_right == MINUS_EXPR)
warning (OPT_Wparentheses,
- "suggest parentheses around arithmetic in operand of ^");
+ "suggest parentheses around arithmetic in operand of %<^%>");
/* Check cases like x^y==z */
- if (TREE_CODE_CLASS (code_left) == tcc_comparison
- || TREE_CODE_CLASS (code_right) == tcc_comparison)
+ else if (TREE_CODE_CLASS (code_left) == tcc_comparison
+ || TREE_CODE_CLASS (code_right) == tcc_comparison)
warning (OPT_Wparentheses,
- "suggest parentheses around comparison in operand of ^");
- }
+ "suggest parentheses around comparison in operand of %<^%>");
+ return;
- if (code == BIT_AND_EXPR)
- {
- if (code_left == PLUS_EXPR || code_left == MINUS_EXPR
- || code_right == PLUS_EXPR || code_right == MINUS_EXPR)
+ case BIT_AND_EXPR:
+ if (code_left == PLUS_EXPR || code_right == PLUS_EXPR)
+ warning (OPT_Wparentheses,
+ "suggest parentheses around %<+%> in operand of %<&%>");
+ else if (code_left == MINUS_EXPR || code_right == MINUS_EXPR)
warning (OPT_Wparentheses,
- "suggest parentheses around + or - in operand of &");
+ "suggest parentheses around %<-%> in operand of %<&%>");
/* Check cases like x&y==z */
- if (TREE_CODE_CLASS (code_left) == tcc_comparison
- || TREE_CODE_CLASS (code_right) == tcc_comparison)
+ else if (TREE_CODE_CLASS (code_left) == tcc_comparison
+ || TREE_CODE_CLASS (code_right) == tcc_comparison)
warning (OPT_Wparentheses,
- "suggest parentheses around comparison in operand of &");
- }
+ "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 %<~%>");
+ return;
- if (code == EQ_EXPR || code == NE_EXPR)
- {
+ case EQ_EXPR:
if (TREE_CODE_CLASS (code_left) == tcc_comparison
|| TREE_CODE_CLASS (code_right) == tcc_comparison)
warning (OPT_Wparentheses,
- "suggest parentheses around comparison in operand of %s",
- code == EQ_EXPR ? "==" : "!=");
- }
- else if (TREE_CODE_CLASS (code) == tcc_comparison)
- {
- if ((TREE_CODE_CLASS (code_left) == tcc_comparison
- && code_left != NE_EXPR && code_left != EQ_EXPR)
- || (TREE_CODE_CLASS (code_right) == tcc_comparison
- && code_right != NE_EXPR && code_right != EQ_EXPR))
- warning (OPT_Wparentheses, "comparisons like X<=Y<=Z do not "
+ "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,
+ "suggest parentheses around comparison in operand of %<!=%>");
+ return;
+
+ default:
+ if (TREE_CODE_CLASS (code) == tcc_comparison
+ && ((TREE_CODE_CLASS (code_left) == tcc_comparison
+ && code_left != NE_EXPR && code_left != EQ_EXPR)
+ || (TREE_CODE_CLASS (code_right) == tcc_comparison
+ && code_right != NE_EXPR && code_right != EQ_EXPR)))
+ warning (OPT_Wparentheses, "comparisons like %<X<=Y<=Z%> do not "
"have their mathematical meaning");
+ return;
}
+#undef NOT_A_BOOLEAN_EXPR_P
}
/* If LABEL (a LABEL_DECL) has not been used, issue a warning. */
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