stdlib: Fix stdbit.h with -Wconversion for older gcc

[thirdparty/glibc.git] / stdlib / stdbit.h

diff --git a/stdlib/stdbit.h b/stdlib/stdbit.h
index 773b2ab72dcae8bdbf6e9acb33eb7525125de5dc..61165dd72592b87721bd6e1601f3b51d4289df8f 100644 (file)
--- a/stdlib/stdbit.h
+++ b/stdlib/stdbit.h
@@ -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 __pacify_uint16 (__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 __pacify_uint8 (__x <= 1
+                        ? 1
+                        : ((uint8_t) 2)
+                          << (__bw8_inline ((uint8_t) (__x - 1)) - 1));
 }
 
 # define stdc_bit_ceil_uc(x) ((unsigned char) __bc8_inline (x))