update C language headers to LLVM 18

release/18.x branch, commit 78b99c73ee4b96fe9ce0e294d4632326afb2db42

lib/include/module.modulemap

@@ -153,10 +153,163 @@ module _Builtin_intrinsics [system] [extern_c] {
   }
 }
 
-module _Builtin_stddef_max_align_t [system] [extern_c] {
-  header "__stddef_max_align_t.h"
+// Start -fbuiltin-headers-in-system-modules affected modules
+
+// The following modules all ignore their headers when
+// -fbuiltin-headers-in-system-modules is passed, and many of
+// those headers join system modules when present.
+
+// e.g. if -fbuiltin-headers-in-system-modules is passed, then
+// float.h will not be in the _Builtin_float module (that module
+// will be empty). If there is a system module that declares
+// `header "float.h"`, then the builtin float.h will join
+// that module. The system float.h (if present) will be treated
+// as a textual header in the sytem module.
+module _Builtin_float [system] {
+  header "float.h"
+  export *
 }
 
+module _Builtin_inttypes [system] {
+  header "inttypes.h"
+  export *
+}
+
+module _Builtin_iso646 [system] {
+  header "iso646.h"
+  export *
+}
+
+module _Builtin_limits [system] {
+  header "limits.h"
+  export *
+}
+
+module _Builtin_stdalign [system] {
+  header "stdalign.h"
+  export *
+}
+
+module _Builtin_stdarg [system] {
+  textual header "stdarg.h"
+
+  explicit module __gnuc_va_list {
+    header "__stdarg___gnuc_va_list.h"
+    export *
+  }
+
+  explicit module __va_copy {
+    header "__stdarg___va_copy.h"
+    export *
+  }
+
+  explicit module va_arg {
+    header "__stdarg_va_arg.h"
+    export *
+  }
+
+  explicit module va_copy {
+    header "__stdarg_va_copy.h"
+    export *
+  }
+
+  explicit module va_list {
+    header "__stdarg_va_list.h"
+    export *
+  }
+}
+
+module _Builtin_stdatomic [system] {
+  header "stdatomic.h"
+  export *
+}
+
+module _Builtin_stdbool [system] {
+  header "stdbool.h"
+  export *
+}
+
+module _Builtin_stddef [system] {
+  textual header "stddef.h"
+
+  // __stddef_max_align_t.h is always in this module, even if
+  // -fbuiltin-headers-in-system-modules is passed.
+  explicit module max_align_t {
+    header "__stddef_max_align_t.h"
+    export *
+  }
+
+  explicit module null {
+    header "__stddef_null.h"
+    export *
+  }
+
+  explicit module nullptr_t {
+    header "__stddef_nullptr_t.h"
+    export *
+  }
+
+  explicit module offsetof {
+    header "__stddef_offsetof.h"
+    export *
+  }
+
+  explicit module ptrdiff_t {
+    header "__stddef_ptrdiff_t.h"
+    export *
+  }
+
+  explicit module rsize_t {
+    header "__stddef_rsize_t.h"
+    export *
+  }
+
+  explicit module size_t {
+    header "__stddef_size_t.h"
+    export *
+  }
+
+  explicit module unreachable {
+    header "__stddef_unreachable.h"
+    export *
+  }
+
+  explicit module wchar_t {
+    header "__stddef_wchar_t.h"
+    export *
+  }
+}
+
+// wint_t is provided by <wchar.h> and not <stddef.h>. It's here
+// for compatibility, but must be explicitly requested. Therefore
+// __stddef_wint_t.h is not part of _Builtin_stddef. It is always in
+// this module even if -fbuiltin-headers-in-system-modules is passed.
+module _Builtin_stddef_wint_t [system] {
+  header "__stddef_wint_t.h"
+  export *
+}
+
+module _Builtin_stdint [system] {
+  header "stdint.h"
+  export *
+}
+
+module _Builtin_stdnoreturn [system] {
+  header "stdnoreturn.h"
+  export *
+}
+
+module _Builtin_tgmath [system] {
+  header "tgmath.h"
+  export *
+}
+
+module _Builtin_unwind [system] {
+  header "unwind.h"
+  export *
+}
+// End -fbuiltin-headers-in-system-modules affected modules
+
 module opencl_c {
   requires opencl
   header "opencl-c.h"