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[PATCH] support: Increase usability of TEST_COMPARE
- From: fweimer at redhat dot com (Florian Weimer)
- To: libc-alpha at sourceware dot org
- Date: Mon, 08 Jan 2018 13:31:11 +0100
- Subject: [PATCH] support: Increase usability of TEST_COMPARE
- Authentication-results: sourceware.org; auth=none
The previous implementation of the TEST_COMPARE macro would fail
to compile code like this:
int ret = res_send (query, sizeof (query), buf, sizeof (buf));
TEST_COMPARE (ret,
sizeof (query)
+ 2 /* Compression reference. */
+ 2 + 2 + 4 + 2 /* Type, class, TTL, RDATA length. */
+ 1 /* Pascal-style string length. */
+ strlen (expected_name));
This resulted in a failed static assertion, "integer conversions
may alter sign of operands". A user of the TEST_COMPARE would have
to add a cast to fix this.
This patch reverts to the original proposed solution of a run-time
check, making TEST_COMPARE usable for comparisons of numbers with
types with different signedness in more contexts.
2018-01-08 Florian Weimer <fweimer@redhat.com>
* support/check.h (TEST_COMPARE): Allow sign mismatch at compile
time. Pass positive flag instead of negative flag to
support_test_compare_failure.
(support_test_compare_failure): Change negative parameter to
positive.
* support/support_test_compare_failure.c (report)
(support_test_compare_failure): Likewise.
* support/tst-test_compare.c (return_ssize_t, return_int): New.
(do_test): Check int/size_t, ssize_t/size_t comparisons.
diff --git a/support/check.h b/support/check.h
index de8fce0dc1..2ac25a187c 100644
--- a/support/check.h
+++ b/support/check.h
@@ -95,7 +95,9 @@ void support_record_failure (void);
typedef __typeof__ (+ (right)) __right_type; \
__left_type __left_value = (left); \
__right_type __right_value = (right); \
- /* Prevent use with floating-point and boolean types. */ \
+ int __left_is_positive = __left_value > 0; \
+ int __right_is_positive = __right_value > 0; \
+ /* Prevent use with floating-point types. */ \
_Static_assert ((__left_type) 1.0 == (__left_type) 1.5, \
"left value has floating-point type"); \
_Static_assert ((__right_type) 1.0 == (__right_type) 1.5, \
@@ -105,33 +107,18 @@ void support_record_failure (void);
"left value fits into long long"); \
_Static_assert (sizeof (__right_value) <= sizeof (long long), \
"right value fits into long long"); \
- /* Make sure that integer conversions does not alter the sign. */ \
- enum \
- { \
- __left_is_unsigned = (__left_type) -1 > 0, \
- __right_is_unsigned = (__right_type) -1 > 0, \
- __unsigned_left_converts_to_wider = (__left_is_unsigned \
- && (sizeof (__left_value) \
- < sizeof (__right_value))), \
- __unsigned_right_converts_to_wider = (__right_is_unsigned \
- && (sizeof (__right_value) \
- < sizeof (__left_value))) \
- }; \
- _Static_assert (__left_is_unsigned == __right_is_unsigned \
- || __unsigned_left_converts_to_wider \
- || __unsigned_right_converts_to_wider, \
- "integer conversions may alter sign of operands"); \
/* Compare the value. */ \
- if (__left_value != __right_value) \
+ if (__left_value != __right_value \
+ || __left_is_positive != __right_is_positive) \
/* Pass the sign for printing the correct value. */ \
support_test_compare_failure \
(__FILE__, __LINE__, \
- #left, __left_value, __left_value < 0, sizeof (__left_type), \
- #right, __right_value, __right_value < 0, sizeof (__right_type)); \
+ #left, __left_value, __left_is_positive, sizeof (__left_type), \
+ #right, __right_value, __right_is_positive, sizeof (__right_type)); \
})
-/* Internal implementation of TEST_COMPARE. LEFT_NEGATIVE and
- RIGHT_NEGATIVE are used to store the sign separately, so that both
+/* Internal implementation of TEST_COMPARE. LEFT_POSITIVE and
+ RIGHT_POSITIVE are used to store the sign separately, so that both
unsigned long long and long long arguments fit into LEFT_VALUE and
RIGHT_VALUE, and the function can still print the original value.
LEFT_SIZE and RIGHT_SIZE specify the size of the argument in bytes,
@@ -139,11 +126,11 @@ void support_record_failure (void);
void support_test_compare_failure (const char *file, int line,
const char *left_expr,
long long left_value,
- int left_negative,
+ int left_positive,
int left_size,
const char *right_expr,
long long right_value,
- int right_negative,
+ int right_positive,
int right_size);
diff --git a/support/support_test_compare_failure.c b/support/support_test_compare_failure.c
index a789283f86..e5596fd121 100644
--- a/support/support_test_compare_failure.c
+++ b/support/support_test_compare_failure.c
@@ -20,14 +20,14 @@
#include <support/check.h>
static void
-report (const char *which, const char *expr, long long value, int negative,
+report (const char *which, const char *expr, long long value, int positive,
int size)
{
printf (" %s: ", which);
- if (negative)
- printf ("%lld", value);
- else
+ if (positive)
printf ("%llu", (unsigned long long) value);
+ else
+ printf ("%lld", value);
unsigned long long mask
= (~0ULL) >> (8 * (sizeof (unsigned long long) - size));
printf (" (0x%llx); from: %s\n", (unsigned long long) value & mask, expr);
@@ -37,11 +37,11 @@ void
support_test_compare_failure (const char *file, int line,
const char *left_expr,
long long left_value,
- int left_negative,
+ int left_positive,
int left_size,
const char *right_expr,
long long right_value,
- int right_negative,
+ int right_positive,
int right_size)
{
support_record_failure ();
@@ -50,6 +50,6 @@ support_test_compare_failure (const char *file, int line,
file, line, left_size * 8, right_size * 8);
else
printf ("%s:%d: numeric comparison failure\n", file, line);
- report (" left", left_expr, left_value, left_negative, left_size);
- report ("right", right_expr, right_value, right_negative, right_size);
+ report (" left", left_expr, left_value, left_positive, left_size);
+ report ("right", right_expr, right_value, right_positive, right_size);
}
diff --git a/support/tst-test_compare.c b/support/tst-test_compare.c
index 340268fadf..123ba1bc3c 100644
--- a/support/tst-test_compare.c
+++ b/support/tst-test_compare.c
@@ -42,6 +42,22 @@ struct bitfield
unsigned long long int u63 : 63;
};
+/* Functions which return signed sizes are common, so test that these
+ results can readily checked using TEST_COMPARE. */
+
+static int
+return_ssize_t (void)
+{
+ return 4;
+}
+
+static int
+return_int (void)
+{
+ return 4;
+}
+
+
static int
do_test (void)
{
@@ -53,6 +69,8 @@ do_test (void)
unsigned short u16 = 3;
TEST_COMPARE (i8, u16);
}
+ TEST_COMPARE (return_ssize_t (), sizeof (char[4]));
+ TEST_COMPARE (return_int (), sizeof (char[4]));
struct bitfield bitfield = { 0 };
TEST_COMPARE (bitfield.i2, bitfield.i3);