@@ -41,6 +41,16 @@
__BEGIN_DECLS
+/* Use __pacify_uint16 (N) instead of (uint16_t) (N) when the cast is helpful
+ only to pacify older GCC (e.g., GCC 10 -Wconversion) or non-GCC. */
+#if __GNUC_PREREQ (11, 0)
+# define __pacify_uint8(n) (n)
+# define __pacify_uint16(n) (n)
+#else
+# define __pacify_uint8(n) ((uint8_t) (n))
+# define __pacify_uint16(n) ((uint16_t) (n))
+#endif
+
/* Count leading zeros. */
extern unsigned int stdc_leading_zeros_uc (unsigned char __x)
__THROW __attribute_const__;
@@ -125,13 +135,13 @@ __clo32_inline (uint32_t __x)
static __always_inline unsigned int
__clo16_inline (uint16_t __x)
{
- return __clz16_inline (~__x);
+ return __clz16_inline (__pacify_uint16 (~__x));
}
static __always_inline unsigned int
__clo8_inline (uint8_t __x)
{
- return __clz8_inline (~__x);
+ return __clz8_inline (__pacify_uint8 (~__x));
}
# define stdc_leading_ones_uc(x) (__clo8_inline (x))
@@ -229,13 +239,13 @@ __cto32_inline (uint32_t __x)
static __always_inline unsigned int
__cto16_inline (uint16_t __x)
{
- return __ctz16_inline (~__x);
+ return __ctz16_inline (__pacify_uint16 (~__x));
}
static __always_inline unsigned int
__cto8_inline (uint8_t __x)
{
- return __ctz8_inline (~__x);
+ return __ctz8_inline (__pacify_uint8 (~__x));
}
# define stdc_trailing_ones_uc(x) (__cto8_inline (x))
@@ -698,13 +708,15 @@ __bf32_inline (uint32_t __x)
static __always_inline uint16_t
__bf16_inline (uint16_t __x)
{
- return __x == 0 ? 0 : ((uint16_t) 1) << (__bw16_inline (__x) - 1);
+ return __pacify_uint16 (__x == 0
+ ? 0 : ((uint16_t) 1) << (__bw16_inline (__x) - 1));
}
static __always_inline uint8_t
__bf8_inline (uint8_t __x)
{
- return __x == 0 ? 0 : ((uint8_t) 1) << (__bw8_inline (__x) - 1);
+ return __pacify_uint8 (__x == 0
+ ? 0 : ((uint8_t) 1) << (__bw8_inline (__x) - 1));
}
# define stdc_bit_floor_uc(x) ((unsigned char) __bf8_inline (x))
@@ -748,13 +760,19 @@ __bc32_inline (uint32_t __x)
static __always_inline uint16_t
__bc16_inline (uint16_t __x)
{
- return __x <= 1 ? 1 : ((uint16_t) 2) << (__bw16_inline (__x - 1) - 1);
+ return (uint16_t) (__x <= 1
+ ? 1
+ : ((uint16_t) 2)
+ << (__bw16_inline ((uint16_t) (__x - 1)) - 1));
}
static __always_inline uint8_t
__bc8_inline (uint8_t __x)
{
- return __x <= 1 ? 1 : ((uint8_t) 2) << (__bw8_inline (__x - 1) - 1);
+ return (uint8_t) (__x <= 1
+ ? 1
+ : ((uint8_t) 2)
+ << (__bw8_inline ((uint8_t) (__x - 1)) - 1));
}
# define stdc_bit_ceil_uc(x) ((unsigned char) __bc8_inline (x))
With gcc 6.5.0, 7.5.0, 8.5.0, and 9.5.0 the tst-stdbit-Wconversion issues the warnings: ../stdlib/stdbit.h: In function ‘__clo16_inline’: ../stdlib/stdbit.h:128:26: error: conversion to ‘uint16_t {aka short unsigned int}’ from ‘int’ may alter its value [-Werror=conversion] return __clz16_inline (~__x); ^ ../stdlib/stdbit.h: In function ‘__clo8_inline’: ../stdlib/stdbit.h:134:25: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion] return __clz8_inline (~__x); ^ ../stdlib/stdbit.h: In function ‘__cto16_inline’: ../stdlib/stdbit.h:232:26: error: conversion to ‘uint16_t {aka short unsigned int}’ from ‘int’ may alter its value [-Werror=conversion] return __ctz16_inline (~__x); ^ ../stdlib/stdbit.h: In function ‘__cto8_inline’: ../stdlib/stdbit.h:238:25: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion] return __ctz8_inline (~__x); ^ ../stdlib/stdbit.h: In function ‘__bf16_inline’: ../stdlib/stdbit.h:701:23: error: conversion to ‘uint16_t {aka short unsigned int}’ from ‘int’ may alter its value [-Werror=conversion] return __x == 0 ? 0 : ((uint16_t) 1) << (__bw16_inline (__x) - 1); ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../stdlib/stdbit.h: In function ‘__bf8_inline’: ../stdlib/stdbit.h:707:23: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion] return __x == 0 ? 0 : ((uint8_t) 1) << (__bw8_inline (__x) - 1); ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../stdlib/stdbit.h: In function ‘__bc16_inline’: ../stdlib/stdbit.h:751:59: error: conversion to ‘uint16_t {aka short unsigned int}’ from ‘int’ may alter its value [-Werror=conversion] return __x <= 1 ? 1 : ((uint16_t) 2) << (__bw16_inline (__x - 1) - 1); ^~~ ../stdlib/stdbit.h:751:23: error: conversion to ‘uint16_t {aka short unsigned int}’ from ‘int’ may alter its value [-Werror=conversion] return __x <= 1 ? 1 : ((uint16_t) 2) << (__bw16_inline (__x - 1) - 1); ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../stdlib/stdbit.h: In function ‘__bc8_inline’: ../stdlib/stdbit.h:757:57: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion] return __x <= 1 ? 1 : ((uint8_t) 2) << (__bw8_inline (__x - 1) - 1); ^~~ ../stdlib/stdbit.h:757:23: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion] return __x <= 1 ? 1 : ((uint8_t) 2) << (__bw8_inline (__x - 1) - 1); It seems to boiler down to __builtin_clz not having a variant for 8 or 16 bits. Fix it by explicit casting to the expected types. Checked on x86_64-linux-gnu and i686-linux-gnu with gcc 9.5.0. --- stdlib/stdbit.h | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-)