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Date: Thu, 25 May 2023 16:44:59 +0200
From: Jens Gustedt <Jens.Gustedt@...ia.fr>
To: musl@...ts.openwall.com
Subject: [C23 const 1/2] C23: change bsearch to a macro that respects the const contract
This adds a macro interface to stdlib that has an additional cast of
the return value to `void const*` for the case that the argument to
the call was also const-qualified. Nothing changes for the function
itself, only the identifier has to be protected with (), such that the
macro does not expand for the function declaration or definition.
---
include/stdlib.h | 12 +++++++++++-
src/include/stdlib.h | 2 ++
src/stdlib/bsearch.c | 2 +-
3 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/include/stdlib.h b/include/stdlib.h
index 68ccd467..f5281777 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -60,7 +60,17 @@ char *getenv (const char *);
int system (const char *);
-void *bsearch (const void *, const void *, size_t, size_t, int (*)(const void *, const void *));
+void * (bsearch) (const void *, const void *, size_t, size_t, int (*)(const void *, const void *));
+#if __STDC_VERSION__ > 201112L
+# define bsearch(K, B, N, S, C) \
+ _Generic( \
+ /* ensure conversion to a void pointer */ \
+ 1 ? (B) : (void*)1, \
+ void const*: (void const*)bsearch((K), (void const*)(B), (N), (S), (C)), \
+ /* volatile qualification of *B is an error for this call */ \
+ default: bsearch((K), (B), (N), (S), (C)) \
+)
+#endif
void qsort (void *, size_t, size_t, int (*)(const void *, const void *));
int abs (int);
diff --git a/src/include/stdlib.h b/src/include/stdlib.h
index 812b04de..f0b03df9 100644
--- a/src/include/stdlib.h
+++ b/src/include/stdlib.h
@@ -16,4 +16,6 @@ hidden void *__libc_calloc(size_t, size_t);
hidden void *__libc_realloc(void *, size_t);
hidden void __libc_free(void *);
+#undef bsearch
+
#endif
diff --git a/src/stdlib/bsearch.c b/src/stdlib/bsearch.c
index fe050ea3..4f62ea37 100644
--- a/src/stdlib/bsearch.c
+++ b/src/stdlib/bsearch.c
@@ -1,6 +1,6 @@
#include <stdlib.h>
-void *bsearch(const void *key, const void *base, size_t nel, size_t width, int (*cmp)(const void *, const void *))
+void *(bsearch)(const void *key, const void *base, size_t nel, size_t width, int (*cmp)(const void *, const void *))
{
void *try;
int sign;
--
2.34.1
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