This patch implements a new warning that warns when controlling
expression of a switch has boolean value. (Intentionally I don't
warn if the controlling expression is (un)signed:1 bit-field.)
I guess the question is if this should be enabled by default or
deserves some new warning option. Since clang does the former,
I did it too and currently this warning is enabled by default.
Regtested/bootstrapped on x86_64-linux, ok for trunk?
2014-04-17 Marek Polacek <pola...@redhat.com>
PR c/60439
c/
* c-typeck.c (c_start_case): Warn if switch condition has boolean
value.
testsuite/
* gcc.dg/pr60439.c: New test.
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index 65aad45..91b1109 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -9344,6 +9344,28 @@ c_start_case (location_t switch_loc,
else
{
tree type = TYPE_MAIN_VARIANT (orig_type);
+ tree e = exp;
+ enum tree_code exp_code;
+
+ while (TREE_CODE (e) == COMPOUND_EXPR)
+ e = TREE_OPERAND (e, 1);
+ exp_code = TREE_CODE (e);
+
+ if (TREE_CODE (type) == BOOLEAN_TYPE
+ || exp_code == TRUTH_ANDIF_EXPR
+ || exp_code == TRUTH_AND_EXPR
+ || exp_code == TRUTH_ORIF_EXPR
+ || exp_code == TRUTH_OR_EXPR
+ || exp_code == TRUTH_XOR_EXPR
+ || exp_code == TRUTH_NOT_EXPR
+ || exp_code == EQ_EXPR
+ || exp_code == NE_EXPR
+ || exp_code == LE_EXPR
+ || exp_code == GE_EXPR
+ || exp_code == LT_EXPR
+ || exp_code == GT_EXPR)
+ warning_at (switch_cond_loc, 0,
+ "switch condition has boolean value");
if (!in_system_header_at (input_location)
&& (type == long_integer_type_node
diff --git gcc/testsuite/gcc.dg/pr60439.c gcc/testsuite/gcc.dg/pr60439.c
index e69de29..26e7c25 100644
--- gcc/testsuite/gcc.dg/pr60439.c
+++ gcc/testsuite/gcc.dg/pr60439.c
@@ -0,0 +1,112 @@
+/* PR c/60439 */
+/* { dg-do compile } */
+
+typedef _Bool bool;
+extern _Bool foo (void);
+
+void
+f1 (const _Bool b)
+{
+ switch (b) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+}
+
+void
+f2 (int a, int b)
+{
+ switch (a && b) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch ((bool) (a && b)) /* { dg-warning "switch condition has boolean
value" } */
+ case 1:
+ break;
+ switch ((a && b) || a) /* { dg-warning "switch condition has boolean value"
} */
+ case 1:
+ break;
+}
+
+void
+f3 (int a)
+{
+ switch (!!a) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (!a) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+}
+
+void
+f4 (void)
+{
+ switch (foo ()) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+}
+
+void
+f5 (int a)
+{
+ switch (a == 3) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (a != 3) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (a > 3) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (a < 3) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (a <= 3) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (a >= 3) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (foo (), foo (), a >= 42) /* { dg-warning "switch condition has
boolean value" } */
+ case 1:
+ break;
+ switch (a == 3, a & 4, a ^ 5, a)
+ case 1:
+ break;
+}
+
+void
+f6 (bool b)
+{
+ switch (b) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (!b) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+ switch (b++) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+}
+
+void
+f7 (void)
+{
+ bool b;
+ switch (b = 1) /* { dg-warning "switch condition has boolean value" } */
+ case 1:
+ break;
+}
+
+void
+f8 (int i)
+{
+ switch (i)
+ case 0:
+ break;
+ switch ((unsigned int) i)
+ case 0:
+ break;
+ switch ((bool) i) /* { dg-warning "switch condition has boolean value" } */
+ case 0:
+ break;
+}
Marek
