[llvm] [cmake] Hardcode some `check_include_file` checks (PR #104706)

[Vlad Serebrennikov via llvm-commits]

================
@@ -17,6 +55,150 @@ include(CheckCompilerVersion)
 include(CheckProblematicConfigurations)
 include(HandleLLVMStdlib)
 
+if (ANDROID OR DRAGONFLY OR FREEBSD OR HAIKU OR LINUX OR NETBSD OR OPENBSD OR SOLARIS)
+  set(HAVE_DLFCN_H 1)
+  set(HAVE_ERRNO_H 1)
+  set(HAVE_FCNTL_H 1)
+  set(HAVE_FENV_H 1)
+  set(HAVE_LINK_H 1)
+  set(HAVE_MACH_MACH_H 0)
+  set(HAVE_MALLOC_MALLOC_H 0)
+  set(HAVE_PTHREAD_H 1)
+  set(HAVE_SIGNAL_H 1)
+  set(HAVE_SYS_IOCTL_H 1)
+  set(HAVE_SYS_MMAN_H 1)
+  set(HAVE_SYS_PARAM_H 1)
+  set(HAVE_SYS_RESOURCE_H 1)
+  set(HAVE_SYS_STAT_H 1)
+  set(HAVE_SYS_TIME_H 1)
+  set(HAVE_SYS_TYPES_H 1)
+  set(HAVE_SYSEXITS_H 1)
+  set(HAVE_TERMIOS_H 1)
+  set(HAVE_UNISTD_H 1)
+elseif (AIX)
+  set(HAVE_DLFCN_H 1)
+  set(HAVE_ERRNO_H 1)
+  set(HAVE_FCNTL_H 1)
+  set(HAVE_FENV_H 0)
+  set(HAVE_LINK_H 0)
+  set(HAVE_MACH_MACH_H 0)
+  set(HAVE_MALLOC_MALLOC_H 0)
+  set(HAVE_PTHREAD_H 1)
+  set(HAVE_SIGNAL_H 1)
+  set(HAVE_SYS_IOCTL_H 0)
+  set(HAVE_SYS_MMAN_H 0)
+  set(HAVE_SYS_PARAM_H 1)
+  set(HAVE_SYS_RESOURCE_H 0)
+  set(HAVE_SYS_STAT_H 1)
+  set(HAVE_SYS_TIME_H 0)
+  set(HAVE_SYS_TYPES_H 1)
+  set(HAVE_SYSEXITS_H 0)
+  set(HAVE_TERMIOS_H 1)
+  set(HAVE_UNISTD_H 1)
+elseif (APPLE)
+  set(HAVE_DLFCN_H 1)
+  set(HAVE_ERRNO_H 1)
+  set(HAVE_FCNTL_H 1)
+  set(HAVE_FENV_H 1)
+  set(HAVE_LINK_H 0)
+  set(HAVE_MACH_MACH_H 1)
+  set(HAVE_MALLOC_MALLOC_H 1)
+  set(HAVE_PTHREAD_H 1)
+  set(HAVE_SIGNAL_H 1)
+  set(HAVE_SYS_IOCTL_H 1)
+  set(HAVE_SYS_MMAN_H 1)
+  set(HAVE_SYS_PARAM_H 1)
+  set(HAVE_SYS_RESOURCE_H 1)
+  set(HAVE_SYS_STAT_H 1)
+  set(HAVE_SYS_TIME_H 1)
+  set(HAVE_SYS_TYPES_H 1)
+  set(HAVE_SYSEXITS_H 1)
+  set(HAVE_TERMIOS_H 1)
+  set(HAVE_UNISTD_H 1)
+elseif (CYGWIN)
+  set(HAVE_DLFCN_H 1)
+  set(HAVE_ERRNO_H 1)
+  set(HAVE_FCNTL_H 1)
+  set(HAVE_FENV_H 1)
+  set(HAVE_LINK_H 0)
+  set(HAVE_MACH_MACH_H 0)
+  set(HAVE_MALLOC_MALLOC_H 0)
+  set(HAVE_PTHREAD_H 1)
+  set(HAVE_SIGNAL_H 1)
+  set(HAVE_SYS_IOCTL_H 1)
+  set(HAVE_SYS_MMAN_H 1)
+  set(HAVE_SYS_PARAM_H 1)
+  set(HAVE_SYS_RESOURCE_H 1)
+  set(HAVE_SYS_STAT_H 1)
+  set(HAVE_SYS_TIME_H 1)
+  set(HAVE_SYS_TYPES_H 1)
+  set(HAVE_SYSEXITS_H 1)
+  set(HAVE_TERMIOS_H 1)
+  set(HAVE_UNISTD_H 1)
+elseif (PURE_WINDOWS)
+  set(HAVE_DLFCN_H 0)
+  set(HAVE_ERRNO_H 1)
+  set(HAVE_FCNTL_H 1)
+  set(HAVE_FENV_H 1)
+  set(HAVE_LINK_H 0)
+  set(HAVE_MACH_MACH_H 0)
+  set(HAVE_MALLOC_MALLOC_H 0)
+  set(HAVE_PTHREAD_H 0)
+  set(HAVE_SIGNAL_H 1)
+  set(HAVE_SYS_IOCTL_H 0)
+  set(HAVE_SYS_MMAN_H 0)
+  set(HAVE_SYS_PARAM_H 0)
+  set(HAVE_SYS_RESOURCE_H 0)
+  set(HAVE_SYS_STAT_H 1)
+  set(HAVE_SYS_TIME_H 0)
+  set(HAVE_SYS_TYPES_H 1)
+  set(HAVE_SYSEXITS_H 0)
+  set(HAVE_TERMIOS_H 0)
+elseif (ZOS)
+  # Confirmed in
+  # https://github.com/llvm/llvm-project/pull/104706#issuecomment-2297109613
+  set(HAVE_DLFCN_H 1)
+  set(HAVE_ERRNO_H 1)
+  set(HAVE_FCNTL_H 1)
+  set(HAVE_FENV_H 1)
+  set(HAVE_LINK_H 0)
+  set(HAVE_MACH_MACH_H 0)
+  set(HAVE_MALLOC_MALLOC_H 0)
+  set(HAVE_PTHREAD_H 1)
+  set(HAVE_SIGNAL_H 1)
+  set(HAVE_SYS_IOCTL_H 1)
+  set(HAVE_SYS_MMAN_H 1)
+  set(HAVE_SYS_PARAM_H 0)
+  set(HAVE_SYS_RESOURCE_H 1)
+  set(HAVE_SYS_STAT_H 1)
+  set(HAVE_SYS_TIME_H 1)
+  set(HAVE_SYS_TYPES_H 1)
+  set(HAVE_SYSEXITS_H 0)
+  set(HAVE_TERMIOS_H 1)
+  set(HAVE_UNISTD_H 1)
+else()
----------------
Endilll wrote:

> In theory, once you set the values, the check queries will early-out because they detect the cached value.

I've never felt I understood cache variables enough to feel comfortable relying on them. But I agree, this should be the case.

> Having it always call the check functions (even if the value is set) may make it easy to add platforms where some of these are known to exist, but others may not be.

Are you sure this would serve a practical purpose? If one cares enough to set some of them beforehand to improve configuration times, I don't see how they would not check the rest.

https://github.com/llvm/llvm-project/pull/104706