build: assume stdint.h

curl requires `stdint.h` from C99, and no longer builds without it since
v8.18.0 (after dropping VS2008 support). Assume it's available, drop
feature checks.

Also:
- drop duplicate `stdint.h` includes.
- introduce internal `HAVE_UINTPTR_T`, enabled by default.
- OS400: disable `HAVE_UINTPTR_T`.
- build: keep cmake pre-fill and `cmp-config.pl` exception because cmake
  and autotools both detect `stdint.h` implicitly.

Co-authored-by: Dan Fandrich
Ref: #20405
Ref: #20384
Follow-up to 2e1a045d89 #17931

Closes #20406

CMakeLists.txt

@@ -1497,7 +1497,6 @@ check_include_file("poll.h"           HAVE_POLL_H)
 check_include_file("pwd.h"            HAVE_PWD_H)
 check_include_file("stdatomic.h"      HAVE_STDATOMIC_H)
 check_include_file("stdbool.h"        HAVE_STDBOOL_H)
-check_include_file("stdint.h"         HAVE_STDINT_H)
 check_include_file("strings.h"        HAVE_STRINGS_H)
 check_include_file("stropts.h"        HAVE_STROPTS_H)
 check_include_file("termio.h"         HAVE_TERMIO_H)

configure.ac

@@ -4000,7 +4000,6 @@ AC_CHECK_HEADERS(
   libgen.h \
   locale.h \
   stdbool.h \
-  stdint.h \
   sys/filio.h \
   sys/eventfd.h,
 dnl to do if not found

lib/config-win32.h

@@ -46,11 +46,6 @@
 #define HAVE_STDBOOL_H 1
 #endif
 
-/* Define to 1 if you have the <stdint.h> header file. */
-#if defined(_MSC_VER) || defined(__MINGW32__)
-#define HAVE_STDINT_H 1
-#endif
-
 /* Define if you have the <sys/param.h> header file. */
 #ifdef __MINGW32__
 #define HAVE_SYS_PARAM_H 1

lib/curl_config-cmake.h.in

@@ -472,9 +472,6 @@
 /* Define to 1 if you have the sendmmsg function. */
 #cmakedefine HAVE_SENDMMSG 1
 
-/* Define to 1 if you have the <stdint.h> header file. */
-#cmakedefine HAVE_STDINT_H 1
-
 /* Define to 1 if you have the 'fsetxattr' function. */
 #cmakedefine HAVE_FSETXATTR 1
 

lib/curl_setup.h

@@ -466,9 +466,8 @@
 #include <curl/stdcheaders.h>
 #endif
 
-#if defined(HAVE_STDINT_H) || defined(USE_WOLFSSL)
 #include <stdint.h>
-#endif
+#define HAVE_UINTPTR_T  /* assume uintptr_t is provided by stdint.h */
 
 #ifdef __DJGPP__
 /* By default, DJGPP provides this type as a version of 'unsigned long' which
@@ -477,6 +476,11 @@
 #define uint32_t unsigned int
 #endif
 
+/* Disable uintptr_t for targets known to miss it from stdint.h */
+#ifdef __OS400__
+#undef HAVE_UINTPTR_T
+#endif
+
 #include <limits.h>
 
 #ifdef _WIN32

lib/curl_setup_once.h

@@ -62,7 +62,7 @@
 
 /* Macro to strip 'const' without triggering a compiler warning.
    Use it for APIs that do not or cannot support the const qualifier. */
-#ifdef HAVE_STDINT_H
+#ifdef HAVE_UINTPTR_T
 #  define CURL_UNCONST(p) ((void *)(uintptr_t)(const void *)(p))
 #else
 #  define CURL_UNCONST(p) ((void *)(p))  /* Fall back to simple cast */

lib/curlx/timeval.c

@@ -117,7 +117,6 @@ void curlx_pnow(struct curltime *pnow)
 
 #elif defined(HAVE_MACH_ABSOLUTE_TIME)
 
-#include <stdint.h>
 #include <mach/mach_time.h>
 
 void curlx_pnow(struct curltime *pnow)

lib/doh.h

@@ -25,10 +25,6 @@
  ***************************************************************************/
 #include "urldata.h"
 
-#ifdef USE_HTTPSRR
-# include <stdint.h>
-#endif
-
 #ifndef CURL_DISABLE_DOH
 
 typedef enum {

lib/dynhds.h

@@ -175,7 +175,6 @@ CURLcode Curl_dynhds_h1_dprint(struct dynhds *dynhds, struct dynbuf *dbuf);
 
 #ifdef USE_NGHTTP2
 
-#include <stdint.h>
 #include <nghttp2/nghttp2.h>
 
 nghttp2_nv *Curl_dynhds_to_nva(struct dynhds *dynhds, size_t *pcount);

lib/formdata.c

@@ -310,7 +310,7 @@ static CURLFORMcode FormAdd(struct curl_httppost **httppost,
   struct curl_httppost *lastnode = NULL;
 
 #define form_ptr_arg(t) (forms ? (t)(void *)avalue : va_arg(params, t))
-#ifdef HAVE_STDINT_H
+#ifdef HAVE_UINTPTR_T
 #define form_int_arg(t) (forms ? (t)(uintptr_t)avalue : va_arg(params, t))
 #else
 #define form_int_arg(t) (forms ? (t)(void *)avalue : va_arg(params, t))

lib/hostip.h

@@ -28,10 +28,6 @@
 #include "hash.h"
 #include "curlx/timeval.h" /* for curltime, timediff_t */
 
-#ifdef USE_HTTPSRR
-# include <stdint.h>
-#endif
-
 /* Allocate enough memory to hold the full name information structs and
  * everything. OSF1 is known to require at least 8872 bytes. The buffer
  * required for storing all possible aliases and IP numbers is according to

lib/http.h

@@ -58,11 +58,6 @@ extern const struct Curl_scheme Curl_scheme_https;
 
 #ifndef CURL_DISABLE_HTTP
 
-#ifdef USE_HTTP3
-#include <stdint.h>
-#endif
-
-
 struct dynhds;
 
 struct http_negotiation {

lib/http2.c

@@ -24,7 +24,6 @@
 #include "curl_setup.h"
 
 #if !defined(CURL_DISABLE_HTTP) && defined(USE_NGHTTP2)
-#include <stdint.h>
 #include <nghttp2/nghttp2.h>
 
 #include "urldata.h"

lib/vtls/cipher_suite.h

@@ -26,7 +26,6 @@
 #include "../curl_setup.h"
 
 #if defined(USE_MBEDTLS) || defined(USE_RUSTLS)
-#include <stdint.h>
 
 /* Lookup IANA id for cipher suite string, returns 0 if not recognized */
 uint16_t Curl_cipher_suite_lookup_id(const char *cs_str, size_t cs_len);