cmake: move global headers to specific checks

Before this patch we added standard headers unconditionally to the
global list of headers used for feature checks. This is unnecessary
and also doesn't help CMake 'Generate' performance. This patch moves
these headers to each feature check where they are actually needed.
Stop using `stddef.h`, as it seems unnecessary.

I've used autotools' `m4/curl-functions.m4` to figure out these
dependencies.

Also delete checking for the C89 standard header `time.h`, that I
missed in the earlier commit.

Ref: 96c29900bcec32dd6bc8e9857c8871ff4b8b8ed9 #11940

Closes #11951

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 557ab026208a0272f41e94833ecff594760ca5b0..e57446ebbf5013429c65eef190007ce4e094c0c0 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -995,11 +995,6 @@ if(CURL_CA_PATH_SET AND NOT USE_OPENSSL AND NOT USE_MBEDTLS)
           "Set CURL_CA_PATH=none or enable one of those TLS backends.")
 endif()
 
-# TODO: offload these headers to the specific tests where they are needed.
-list(APPEND CURL_INCLUDES "string.h")
-list(APPEND CURL_INCLUDES "stdlib.h")
-list(APPEND CURL_INCLUDES "stddef.h")
-
 # Check for header files
 if(NOT UNIX)
   check_include_file_concat("windows.h"      HAVE_WINDOWS_H)
@@ -1044,7 +1039,6 @@ check_include_file_concat("strings.h"        HAVE_STRINGS_H)
 check_include_file_concat("stropts.h"        HAVE_STROPTS_H)
 check_include_file_concat("termio.h"         HAVE_TERMIO_H)
 check_include_file_concat("termios.h"        HAVE_TERMIOS_H)
-check_include_file_concat("time.h"           HAVE_TIME_H)
 check_include_file_concat("unistd.h"         HAVE_UNISTD_H)
 check_include_file_concat("utime.h"          HAVE_UTIME_H)
 
@@ -1082,18 +1076,18 @@ elseif(HAVE_LIBSOCKET)
 endif()
 
 check_symbol_exists(fchmod        "${CURL_INCLUDES}" HAVE_FCHMOD)
-check_symbol_exists(basename      "${CURL_INCLUDES}" HAVE_BASENAME)
+check_symbol_exists(basename      "${CURL_INCLUDES};string.h" HAVE_BASENAME)
 check_symbol_exists(socket        "${CURL_INCLUDES}" HAVE_SOCKET)
 check_symbol_exists(socketpair    "${CURL_INCLUDES}" HAVE_SOCKETPAIR)
 check_symbol_exists(recv          "${CURL_INCLUDES}" HAVE_RECV)
 check_symbol_exists(send          "${CURL_INCLUDES}" HAVE_SEND)
 check_symbol_exists(sendmsg       "${CURL_INCLUDES}" HAVE_SENDMSG)
 check_symbol_exists(select        "${CURL_INCLUDES}" HAVE_SELECT)
-check_symbol_exists(strdup        "${CURL_INCLUDES}" HAVE_STRDUP)
-check_symbol_exists(strtok_r      "${CURL_INCLUDES}" HAVE_STRTOK_R)
-check_symbol_exists(strcasecmp    "${CURL_INCLUDES}" HAVE_STRCASECMP)
-check_symbol_exists(stricmp       "${CURL_INCLUDES}" HAVE_STRICMP)
-check_symbol_exists(strcmpi       "${CURL_INCLUDES}" HAVE_STRCMPI)
+check_symbol_exists(strdup        "${CURL_INCLUDES};string.h" HAVE_STRDUP)
+check_symbol_exists(strtok_r      "${CURL_INCLUDES};string.h" HAVE_STRTOK_R)
+check_symbol_exists(strcasecmp    "${CURL_INCLUDES};string.h" HAVE_STRCASECMP)
+check_symbol_exists(stricmp       "${CURL_INCLUDES};string.h" HAVE_STRICMP)
+check_symbol_exists(strcmpi       "${CURL_INCLUDES};string.h" HAVE_STRCMPI)
 check_symbol_exists(alarm         "${CURL_INCLUDES}" HAVE_ALARM)
 check_symbol_exists(getppid       "${CURL_INCLUDES}" HAVE_GETPPID)
 check_symbol_exists(utimes        "${CURL_INCLUDES}" HAVE_UTIMES)
@@ -1106,15 +1100,15 @@ check_symbol_exists(getpwuid      "${CURL_INCLUDES}" HAVE_GETPWUID)
 check_symbol_exists(getpwuid_r    "${CURL_INCLUDES}" HAVE_GETPWUID_R)
 check_symbol_exists(geteuid       "${CURL_INCLUDES}" HAVE_GETEUID)
 check_symbol_exists(utime         "${CURL_INCLUDES}" HAVE_UTIME)
-check_symbol_exists(gmtime_r      "${CURL_INCLUDES}" HAVE_GMTIME_R)
+check_symbol_exists(gmtime_r      "${CURL_INCLUDES};stdlib.h;time.h" HAVE_GMTIME_R)
 
 check_symbol_exists(gethostbyname_r "${CURL_INCLUDES}" HAVE_GETHOSTBYNAME_R)
 
 check_symbol_exists(signal         "${CURL_INCLUDES}" HAVE_SIGNAL)
-check_symbol_exists(strtoll        "${CURL_INCLUDES}" HAVE_STRTOLL)
-check_symbol_exists(strerror_r     "${CURL_INCLUDES}" HAVE_STRERROR_R)
+check_symbol_exists(strtoll        "${CURL_INCLUDES};stdlib.h" HAVE_STRTOLL)
+check_symbol_exists(strerror_r     "${CURL_INCLUDES};stdlib.h;string.h" HAVE_STRERROR_R)
 check_symbol_exists(siginterrupt   "${CURL_INCLUDES}" HAVE_SIGINTERRUPT)
-check_symbol_exists(getaddrinfo    "${CURL_INCLUDES}" HAVE_GETADDRINFO)
+check_symbol_exists(getaddrinfo    "${CURL_INCLUDES};stdlib.h;string.h" HAVE_GETADDRINFO)
 if(WIN32)
   set(HAVE_GETADDRINFO_THREADSAFE ${HAVE_GETADDRINFO})
 endif()
@@ -1136,11 +1130,11 @@ if(NOT MSVC OR (MSVC_VERSION GREATER_EQUAL 1900))
   check_symbol_exists(snprintf       "stdio.h" HAVE_SNPRINTF)
 endif()
 check_function_exists(mach_absolute_time HAVE_MACH_ABSOLUTE_TIME)
-check_symbol_exists(inet_ntop      "${CURL_INCLUDES}" HAVE_INET_NTOP)
+check_symbol_exists(inet_ntop      "${CURL_INCLUDES};stdlib.h;string.h" HAVE_INET_NTOP)
 if(MSVC AND (MSVC_VERSION LESS_EQUAL 1600))
   set(HAVE_INET_NTOP OFF)
 endif()
-check_symbol_exists(inet_pton      "${CURL_INCLUDES}" HAVE_INET_PTON)
+check_symbol_exists(inet_pton      "${CURL_INCLUDES};stdlib.h;string.h" HAVE_INET_PTON)
 
 check_symbol_exists(fsetxattr "${CURL_INCLUDES}" HAVE_FSETXATTR)
 if(HAVE_FSETXATTR)