Merge pull request ocaml#12714 from MisterDA/cc-Wundef

Warn if an undefined identifier is evaluated in an `#if` directive (enable `-Wundef`)

Changes

@@ -571,6 +571,12 @@ Working version
    review by Vincent Laviron, KC Sivaramakrishnan and Xavier Leroy,
    report by Vesa Karvonen and Carine Morel)
 
+- #12714: check whether macros are defined before using them to ensure
+  that the headers can always be used in code which turns on -Wundef
+  (or equivalent).
+  (Antonin Décimo, review by Miod Vallat, Gabriel Scherer,
+   Xavier Leroy, and David Allsopp)
+
 OCaml 5.1.1
 -----------
 

configure.ac

@@ -770,7 +770,7 @@ AS_CASE([$ocaml_cv_cc_vendor],
   [outputobj='-o '
   warn_error_flag='-Werror'
   cc_warnings="-Wall -Wint-conversion -Wstrict-prototypes \
--Wold-style-definition"])
+-Wold-style-definition -Wundef"])
 
 # Use -Wold-style-declaration if supported
 AX_CHECK_COMPILE_FLAG([-Wold-style-declaration],

otherlibs/unix/getcwd.c

@@ -21,7 +21,7 @@
 #include <caml/osdeps.h>
 #include "unixsupport.h"
 
-#if !defined (_WIN32) && !macintosh
+#if !defined(_WIN32)
 #include <sys/param.h>
 #endif
 

otherlibs/unix/gethost.c

@@ -31,11 +31,6 @@
 
 #define NETDB_BUFFER_SIZE 10000
 
-#ifdef _WIN32
-#define GETHOSTBYADDR_IS_REENTRANT 1
-#define GETHOSTBYNAME_IS_REENTRANT 1
-#endif
-
 static value alloc_one_addr_4(char const *a)
 {
   return caml_alloc_initialized_string(4, a);
@@ -101,7 +96,15 @@ CAMLprim value caml_unix_gethostbyaddr(value a)
 #if HAS_IPV6
   }
 #endif
-#if HAS_GETHOSTBYADDR_R == 7
+#if !defined(HAS_GETHOSTBYADDR_R)
+#ifdef _WIN32
+  caml_enter_blocking_section();
+#endif
+  hp = gethostbyaddr(adr, addr_len, addr_type);
+#ifdef _WIN32
+  caml_leave_blocking_section();
+#endif
+#elif HAS_GETHOSTBYADDR_R == 7
   struct hostent h;
   char buffer[NETDB_BUFFER_SIZE];
   int h_errnop;
@@ -118,14 +121,6 @@ CAMLprim value caml_unix_gethostbyaddr(value a)
                        &h, buffer, sizeof(buffer), &hp, &h_errnop);
   caml_leave_blocking_section();
   if (rc != 0) hp = NULL;
-#else
-#ifdef GETHOSTBYADDR_IS_REENTRANT
-  caml_enter_blocking_section();
-#endif
-  hp = gethostbyaddr(adr, addr_len, addr_type);
-#ifdef GETHOSTBYADDR_IS_REENTRANT
-  caml_leave_blocking_section();
-#endif
 #endif
   if (hp == (struct hostent *) NULL) caml_raise_not_found();
   return alloc_host_entry(hp);
@@ -135,7 +130,7 @@ CAMLprim value caml_unix_gethostbyname(value name)
 {
   struct hostent * hp;
   char * hostname;
-#if HAS_GETHOSTBYNAME_R
+#ifdef HAS_GETHOSTBYNAME_R
   struct hostent h;
   char buffer[NETDB_BUFFER_SIZE];
   int err;
@@ -145,7 +140,15 @@ CAMLprim value caml_unix_gethostbyname(value name)
 
   hostname = caml_stat_strdup(String_val(name));
 
-#if HAS_GETHOSTBYNAME_R == 5
+#if !defined(HAS_GETHOSTBYNAME_R)
+#ifdef _WIN32
+  caml_enter_blocking_section();
+#endif
+  hp = gethostbyname(hostname);
+#ifdef _WIN32
+  caml_leave_blocking_section();
+#endif
+#elif HAS_GETHOSTBYNAME_R == 5
   {
     caml_enter_blocking_section();
     hp = gethostbyname_r(hostname, &h, buffer, sizeof(buffer), &err);
@@ -159,14 +162,6 @@ CAMLprim value caml_unix_gethostbyname(value name)
     caml_leave_blocking_section();
     if (rc != 0) hp = NULL;
   }
-#else
-#ifdef GETHOSTBYNAME_IS_REENTRANT
-  caml_enter_blocking_section();
-#endif
-  hp = gethostbyname(hostname);
-#ifdef GETHOSTBYNAME_IS_REENTRANT
-  caml_leave_blocking_section();
-#endif
 #endif
 
   caml_stat_free(hostname);

runtime/caml/fiber.h

@@ -101,6 +101,8 @@ struct stack_info {
 #elif defined(TARGET_power)
 /* ELF ABI: 4 reserved words at bottom of C stack */
   #define Reserved_space_c_stack_link 4 * 8
+#else
+  #define Reserved_space_c_stack_link 0
 #endif
 
 /* This structure is used for storing the OCaml return pointer when

runtime/caml/misc.h

@@ -42,8 +42,9 @@
   #define CAMLdeprecated_typedef(name, type) typedef type name
 #endif
 
-#if defined(__GNUC__) && __STDC_VERSION__ >= 199901L \
- || defined(_MSC_VER) && _MSC_VER >= 1925
+#if defined(__GNUC__)                                           \
+    && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L \
+    || defined(_MSC_VER) && _MSC_VER >= 1925
 
 #define CAML_STRINGIFY(x) #x
 #ifdef _MSC_VER
@@ -84,9 +85,10 @@ CAMLdeprecated_typedef(addr, char *);
    Note: CAMLnoreturn is a different macro defined in memory.h,
    to be used in function bodies rather than as a function attribute.
 */
-#if __STDC_VERSION__ >= 202300L || __cplusplus >= 201103L
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202300L    \
+    || defined(__cplusplus) && __cplusplus >= 201103L
   #define CAMLnoret [[noreturn]]
-#elif __STDC_VERSION__ >= 201112L
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
   #define CAMLnoret _Noreturn
 #elif defined(__GNUC__)
   #define CAMLnoret  __attribute__ ((noreturn))
@@ -561,7 +563,7 @@ CAMLextern int caml_snwprintf(wchar_t * buf,
 #    define CAMLno_asan __attribute__((no_sanitize("address")))
 #  endif
 #else
-#  if __SANITIZE_ADDRESS__
+#  if defined(__SANITIZE_ADDRESS__)
 #    undef CAMLno_asan
 #    define CAMLno_asan __attribute__((no_sanitize_address))
 #  endif

runtime/caml/tsan.h

@@ -34,7 +34,7 @@
 #    endif
 #  endif
 #else
-#  if __SANITIZE_THREAD__
+#  if defined(__SANITIZE_THREAD__)
 #    undef CAMLreally_no_tsan
 #    define CAMLreally_no_tsan __attribute__((no_sanitize_thread))
 #  endif

runtime/misc.c

@@ -15,7 +15,7 @@
 
 #define CAML_INTERNALS
 
-#if _MSC_VER >= 1400 && _MSC_VER < 1700
+#if defined(_MSC_VER) && _MSC_VER >= 1400 && _MSC_VER < 1700
 /* Microsoft introduced a regression in Visual Studio 2005 (technically it's
    not present in the Windows Server 2003 SDK which has a pre-release version)
    and the abort function ceased to be declared __declspec(noreturn). This was

runtime/startup_byt.c

@@ -404,7 +404,7 @@ static void do_print_config(void)
          "false");
 #endif
   printf("windows_unicode: %s\n",
-#if WINDOWS_UNICODE
+#if defined(WINDOWS_UNICODE) && WINDOWS_UNICODE != 0
          "true");
 #else
          "false");