Use GCC's -Wsuggest-attribute warning

configure.ac

@@ -1066,6 +1066,14 @@ for flag in '-Wimplicit-fallthrough=5' '-Wimplicit-fallthrough'; do
     [cc_warnings="$cc_warnings $flag"; break], [], [$warn_error_flag])
 done
 
+# Use -Wsuggest-attribute=attribute_name if supported
+# Don't apply pure to primitives. const has some false-positive suggestions.
+for attribute_name in noreturn malloc format; do
+  AX_CHECK_COMPILE_FLAG([-Wsuggest-attribute=$attribute_name],
+    [cc_warnings="$cc_warnings -Wsuggest-attribute=$attribute_name"], [],
+    [$warn_error_flag])
+done
+
 AS_CASE([$enable_warn_error,OCAML__DEVELOPMENT_VERSION],
   [yes,*|,true],
     [cc_warnings="$cc_warnings $warn_error_flag"])

ocamltest/run.h

@@ -25,6 +25,7 @@
 typedef char_os **array;
 
 typedef void Logger(void *, const char *, va_list ap);
+#define Logger CAMLformat(__printf__, 2, 0) Logger
 
 typedef struct {
   char_os *program;

ocamltest/run_common.h

@@ -25,11 +25,13 @@ static int is_defined(const char_os *str)
   return (str != NULL) && (*str != 0);
 }
 
+CAMLformat(__printf__, 2, 0)
 static void defaultLogger(void *where, const char *format, va_list ap)
 {
   vfprintf(stderr, format, ap);
 }
 
+CAMLformat(__printf__, 3, 4)
 static void mylog(Logger *logger, void *loggerData, const char *fmt, ...)
 {
   va_list ap;
@@ -38,6 +40,7 @@ static void mylog(Logger *logger, void *loggerData, const char *fmt, ...)
   va_end(ap);
 }
 
+CAMLformat(__printf__, 4, 5)
 static void error_with_location(
   const char *file, int line,
   const command_settings *settings,

ocamltest/run_stubs.c

@@ -58,6 +58,7 @@ static void free_cstringvect(array v)
   caml_stat_free(v);
 }
 
+CAMLformat(__printf__, 2, 0)
 static void logToChannel(void *voidchannel, const char *fmt, va_list ap)
 {
   struct channel *channel = (struct channel *) voidchannel;

ocamltest/run_unix.c

@@ -46,7 +46,7 @@ error_with_location(__FILE__, __LINE__, settings, msg, ## __VA_ARGS__)
   For a more portable (but also more complex) solution, see
   http://stackoverflow.com/questions/20818800/variadic-macro-and-trailing-comma
 */
-
+CAMLformat(__printf__, 4, 5)
 static void myperror_with_location(
   const char *file, int line,
   const command_settings *settings,

otherlibs/unix/execv.c

@@ -20,7 +20,7 @@
 #include <caml/osdeps.h>
 #include "caml/unixsupport.h"
 
-CAMLprim value caml_unix_execv(value path, value args)
+CAMLnoret CAMLprim void caml_unix_execv(value path, value args)
 {
   char_os * wpath;
   char_os ** argv;
@@ -31,6 +31,4 @@ CAMLprim value caml_unix_execv(value path, value args)
   caml_stat_free(wpath);
   caml_unix_cstringvect_free(argv);
   caml_uerror("execv", path);
-  return Val_unit;                  /* never reached, but suppress warnings */
-                                /* from smart compilers */
 }

otherlibs/unix/execve.c

@@ -20,7 +20,7 @@
 #include <caml/osdeps.h>
 #include "caml/unixsupport.h"
 
-CAMLprim value caml_unix_execve(value path, value args, value env)
+CAMLnoret CAMLprim void caml_unix_execve(value path, value args, value env)
 {
   char_os ** argv;
   char_os ** envp;
@@ -34,6 +34,4 @@ CAMLprim value caml_unix_execve(value path, value args, value env)
   caml_unix_cstringvect_free(argv);
   caml_unix_cstringvect_free(envp);
   caml_uerror("execve", path);
-  return Val_unit;                  /* never reached, but suppress warnings */
-                                /* from smart compilers */
 }

otherlibs/unix/execvp.c

@@ -22,7 +22,7 @@
 #include <caml/osdeps.h>
 #include "caml/unixsupport.h"
 
-CAMLprim value caml_unix_execvp(value path, value args)
+CAMLnoret CAMLprim void caml_unix_execvp(value path, value args)
 {
   char_os ** argv;
   char_os * wpath;
@@ -33,8 +33,6 @@ CAMLprim value caml_unix_execvp(value path, value args)
   caml_stat_free(wpath);
   caml_unix_cstringvect_free(argv);
   caml_uerror("execvp", path);
-  return Val_unit;                  /* never reached, but suppress warnings */
-                                    /* from smart compilers */
 }
 
 #ifndef HAS_EXECVPE
@@ -43,7 +41,7 @@ int caml_unix_execvpe_emulation(const char * name,
                            char * const envp[]);
 #endif
 
-CAMLprim value caml_unix_execvpe(value path, value args, value env)
+CAMLnoret CAMLprim void caml_unix_execvpe(value path, value args, value env)
 {
   char_os ** argv;
   char_os ** envp;
@@ -63,8 +61,6 @@ CAMLprim value caml_unix_execvpe(value path, value args, value env)
   caml_unix_cstringvect_free(argv);
   caml_unix_cstringvect_free(envp);
   caml_unix_error(err, "execvpe", path);
-  return Val_unit;                  /* never reached, but suppress warnings */
-                                    /* from smart compilers */
 }
 
 #ifndef HAS_EXECVPE

otherlibs/unix/exit.c

@@ -16,9 +16,7 @@
 #include <caml/mlvalues.h>
 #include "caml/unixsupport.h"
 
-CAMLprim value caml_unix_exit(value n)
+CAMLnoret CAMLprim void caml_unix_exit(value n)
 {
   _exit(Int_val(n));
-  return Val_unit;                  /* never reached, but suppress warnings */
-                                    /* from smart compilers */
 }

runtime/caml/addrmap.h

@@ -36,7 +36,8 @@ value caml_addrmap_lookup(struct addrmap* t, value k);
 #define ADDRMAP_NOT_PRESENT ((value)(0))
 #define ADDRMAP_INVALID_KEY ((value)(0))
 
-value* caml_addrmap_insert_pos(struct addrmap* t, value k);
+value* caml_addrmap_insert_pos(struct addrmap* t, value k)
+  CAMLreturns_nonnull;
 
 /* must not already be present */
 void caml_addrmap_insert(struct addrmap* t, value k, value v);

runtime/caml/alloc.h

@@ -56,10 +56,7 @@ CAMLextern value caml_copy_nativeint (intnat);  /* defined in [ints.c] */
 CAMLextern value caml_alloc_array (value (*funct) (char const *),
                                    char const * const * array);
 CAMLextern value caml_alloc_sprintf(const char * format, ...)
-#if __has_attribute(format) || defined(__GNUC__)
-  __attribute__ ((format (printf, 1, 2)))
-#endif
-;
+  CAMLformat(__printf__, 1, 2);
 CAMLextern value caml_alloc_some(value);
 
 typedef void (*final_fun)(value);

runtime/caml/custom.h

@@ -83,7 +83,8 @@ CAMLextern mlsize_t caml_custom_get_max_major (void);
 extern struct custom_operations *
           caml_find_custom_operations(const char * ident);
 extern struct custom_operations *
-          caml_final_custom_operations(void (*fn)(value));
+          caml_final_custom_operations(void (*fn)(value))
+  CAMLreturns_nonnull;
 
 extern void caml_init_custom_operations(void);
 

runtime/caml/debugger.h

@@ -37,7 +37,12 @@ void caml_debugger_init (void);
 void caml_debugger (enum event_kind event, value param);
 CAMLextern void caml_debugger_cleanup_fork (void);
 
-opcode_t caml_debugger_saved_instruction(code_t pc);
+#if !defined(HAS_SOCKETS) || defined(NATIVE_CODE)
+CAMLnoret void
+#else
+opcode_t
+#endif
+caml_debugger_saved_instruction(code_t pc);
 
 /* Communication protocol */
 

runtime/caml/domain_state.h

@@ -51,7 +51,7 @@ enum {
   #define Caml_state_opt caml_state
 #else
 #if __has_attribute(pure) || defined(__GNUC__)
-  __attribute__((pure))
+  __attribute__((__pure__))
 #endif
   CAMLextern caml_domain_state* caml_get_domain_state(void);
   #define Caml_state_opt (caml_get_domain_state())

runtime/caml/dynlink.h

@@ -44,7 +44,8 @@ extern void caml_free_shared_libs(void);
 /* If found, parse $OCAMLLIB/ld.conf, $CAMLLIB/ld.conf and stdlib/ld.conf in
    that order and add the lines read to table. */
 extern char_os * caml_parse_ld_conf(const char_os * stdlib,
-                                    struct ext_table * table);
+                                    struct ext_table * table)
+  CAMLreturns_nonnull;
 
 #endif /* CAML_INTERNALS */
 

runtime/caml/io.h

@@ -66,9 +66,9 @@ enum {
 /* Creating and closing channels from C */
 
 CAMLextern void caml_close_channel (struct channel *);
-CAMLalloc(caml_close_channel, 1) CAMLreturns_nonnull()
+CAMLalloc(caml_close_channel, 1) CAMLreturns_nonnull
 CAMLextern struct channel * caml_open_descriptor_in (int);
-CAMLalloc(caml_close_channel, 1) CAMLreturns_nonnull()
+CAMLalloc(caml_close_channel, 1) CAMLreturns_nonnull
 CAMLextern struct channel * caml_open_descriptor_out (int);
 CAMLextern file_offset caml_channel_size (struct channel *);
 CAMLextern void caml_seek_in (struct channel *, file_offset);

runtime/caml/memory.h

@@ -86,7 +86,7 @@ CAMLextern void caml_stat_free(caml_stat_block);
    (in bytes) and returns a pointer to it. It throws an OCaml exception in case
    the request fails, and so requires the runtime lock to be held.
 */
-CAMLmalloc(caml_stat_free, 1, 1) CAMLreturns_nonnull()
+CAMLmalloc(caml_stat_free, 1, 1) CAMLreturns_nonnull
 CAMLextern caml_stat_block caml_stat_alloc(asize_t);
 
 /* [caml_stat_alloc_noexc(size)] allocates a memory block of the requested
@@ -102,7 +102,7 @@ CAMLextern caml_stat_block caml_stat_alloc_noexc(asize_t);
    well as the unaligned [block] (as an output parameter). It throws an OCaml
    exception in case the request fails, and so requires the runtime lock.
 */
-CAMLaligned_alloc(caml_stat_free, 1, 1, 2) CAMLreturns_nonnull()
+CAMLaligned_alloc(caml_stat_free, 1, 1, 2) CAMLreturns_nonnull
 CAMLextern void* caml_stat_alloc_aligned(asize_t, int modulo, caml_stat_block*);
 
 /* [caml_stat_alloc_aligned_noexc] is a variant of [caml_stat_alloc_aligned]
@@ -129,7 +129,7 @@ CAMLextern caml_stat_block caml_stat_calloc_noexc(asize_t, asize_t);
    portion is indeterminate. The function throws an OCaml exception in case the
    request fails, and so requires the runtime lock to be held.
 */
-CAMLrealloc(2) CAMLreturns_nonnull()
+CAMLrealloc(2) CAMLreturns_nonnull
 CAMLextern caml_stat_block caml_stat_resize(caml_stat_block, asize_t);
 
 /* [caml_stat_resize_noexc] is a variant of [caml_stat_resize] that returns NULL
@@ -146,7 +146,7 @@ typedef char* caml_stat_string;
    copy of the null-terminated string [s]. It throws an OCaml exception in case
    the request fails, and so requires the runtime lock to be held.
 */
-CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull()
+CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull
 CAMLextern caml_stat_string caml_stat_strdup(const char *s);
 
 /* [caml_stat_strdup_noexc] is a variant of [caml_stat_strdup] that returns NULL
@@ -160,7 +160,7 @@ CAMLextern caml_stat_string caml_stat_strdup_noexc(const char *s);
  * obvious equivalents of [caml_stat_strdup] and
  * [caml_stat_strdup_noexc] for wide characters.
  */
-CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull()
+CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull
 CAMLextern wchar_t* caml_stat_wcsdup(const wchar_t *s);
 CAMLalloc(caml_stat_free, 1)
 CAMLextern wchar_t* caml_stat_wcsdup_noexc(const wchar_t *s);
@@ -172,7 +172,7 @@ CAMLextern wchar_t* caml_stat_wcsdup_noexc(const wchar_t *s);
    implementation of the Windows-only functions
    caml_stat_char_array_{to,from}_utf16.
 */
-CAMLmalloc(caml_stat_free, 1, 2) CAMLreturns_nonnull()
+CAMLmalloc(caml_stat_free, 1, 2) CAMLreturns_nonnull
 CAMLextern caml_stat_string caml_stat_memdup(const char *s, asize_t size,
                                              asize_t *out_size);
 
@@ -181,10 +181,10 @@ CAMLextern caml_stat_string caml_stat_memdup(const char *s, asize_t size,
    except for the very last one. It throws an OCaml exception in case the
    request fails, and so requires the runtime lock to be held.
 */
-CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull()
+CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull
 CAMLextern caml_stat_string caml_stat_strconcat(int n, ...);
 #ifdef _WIN32
-CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull()
+CAMLalloc(caml_stat_free, 1) CAMLreturns_nonnull
 CAMLextern wchar_t* caml_stat_wcsconcat(int n, ...);
 #endif