Audit the installed headers for C++ compatibility

C++ name mangling applies to symbols: variable and function names. The
rule of thumb is to enclose public symbols declarations in blocks:

    #ifdef __cplusplus
    extern "C" {
    #endif

    /* symbols go here */

    #ifdef __cplusplus
    }
    #endif

Symbols protected by CAML_INTERNALS blocks need not to be covered.

Headers that contain definitions incompatible with C++, such as
_Atomic, also need protection.

Changes

@@ -141,6 +141,9 @@ Working version
   (Florian Angeletti, report by Nailen Matschke, review by Gabriel Scherer, and
   Leo White)
 
+- #13541, #?????: Fix headers for C++ inclusion.
+  (Antonin Décimo, review by ?, report by Kate Deplaix)
+
 OCaml 5.3.0
 ___________
 

otherlibs/runtime_events/caml/runtime_events_consumer.h

@@ -21,6 +21,10 @@
 
 #include "caml/runtime_events.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Create a cursor to read events from an runtime_events. Cursors can be created
    for runtime_events in and out of process. An runtime_events may have
    multiple cursors reading from it at any point in time and a program may have
@@ -95,4 +99,8 @@ CAMLextern runtime_events_error caml_runtime_events_read_poll(
     void *callback_data,
     uintnat max_events, uintnat *events_consumed);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* CAML_RUNTIME_EVENTS_CONSUMER_H */

runtime/caml/address_class.h

@@ -43,6 +43,10 @@
 #include "misc.h"
 #include "mlvalues.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 CAMLextern uintnat caml_minor_heaps_start;
 CAMLextern uintnat caml_minor_heaps_end;
 
@@ -59,4 +63,8 @@ CAMLextern uintnat caml_minor_heaps_end;
 #define Is_in_heap_or_young(a) 1
 #define Is_in_value_area(a) 1
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* CAML_ADDRESS_CLASS_H */

runtime/caml/addrmap.h

@@ -17,6 +17,10 @@
 
 #include "mlvalues.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* An addrmap is a value -> value hashmap, where
    the values are blocks */
 
@@ -95,7 +99,8 @@ Caml_inline addrmap_iterator caml_addrmap_iterator(struct addrmap* t)
   return caml_addrmap_next(t, (uintnat)(-1));
 }
 
-
+#ifdef __cplusplus
+}
 #endif
 
 #endif /* CAML_ADDRMAP_H */

runtime/caml/backtrace.h

@@ -18,6 +18,10 @@
 
 #include "mlvalues.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* [caml_record_backtraces] controls backtrace recording.
  * This function can be called at runtime by user-code, or during
  * initialization if backtraces were requested.
@@ -27,6 +31,10 @@
  */
 CAMLextern void caml_record_backtraces(int);
 
+#ifdef __cplusplus
+}
+#endif
+
 #ifdef CAML_INTERNALS
 
 #include "exec.h"

runtime/caml/custom.h

@@ -75,6 +75,10 @@ CAMLextern mlsize_t caml_custom_get_max_major (void);
 /* Global variable moved to Caml_state in 4.10 */
 #define caml_compare_unordered (Caml_state_field(compare_unordered))
 
+#ifdef __cplusplus
+}
+#endif
+
 #ifdef CAML_INTERNALS
 extern struct custom_operations *
           caml_find_custom_operations(const char * ident);
@@ -89,8 +93,4 @@ extern const struct custom_operations caml_int64_ops;
 extern const struct custom_operations caml_ba_ops;
 #endif /* CAML_INTERNALS */
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* CAML_CUSTOM_H */

runtime/caml/domain.h

@@ -17,10 +17,6 @@
 #ifndef CAML_DOMAIN_H
 #define CAML_DOMAIN_H
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #ifdef CAML_INTERNALS
 
 #include <stdbool.h>
@@ -250,8 +246,4 @@ bool caml_free_domains(void);
 
 #endif /* CAML_INTERNALS */
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* CAML_DOMAIN_H */

runtime/caml/domain_state.h

@@ -22,6 +22,10 @@
 
 #include "misc.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define NUM_EXTRA_PARAMS 64
 typedef value extra_params_area[NUM_EXTRA_PARAMS];
 
@@ -67,4 +71,8 @@ CAMLnoret CAMLextern void caml_bad_caml_state(void);
 
 #define Caml_state_field(field) (Caml_state->field)
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* CAML_STATE_H */

runtime/caml/hooks.h

@@ -19,10 +19,6 @@
 #include "misc.h"
 #include "memory.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #ifdef CAML_INTERNALS
 
 #ifdef NATIVE_CODE
@@ -36,8 +32,4 @@ CAMLextern void (*caml_natdynlink_hook)(void* handle, const char* unit);
 
 #endif /* CAML_INTERNALS */
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* CAML_HOOKS_H */

runtime/caml/intext.h

@@ -131,6 +131,9 @@ void caml_free_extern_state (void);
 void caml_output_val (struct channel * chan, value v, value flags);
   /* Output [v] with flags [flags] on the channel [chan]. */
 
+value caml_input_val (struct channel * chan);
+  /* Read a structured value from the channel [chan]. */
+
 void caml_free_intern_state (void);
 
 /* Compression hooks */
@@ -160,11 +163,6 @@ CAMLextern intnat caml_output_value_to_block(value v, value flags,
      in bytes.  Return the number of bytes actually written in buffer.
      Raise [Failure] if buffer is too short. */
 
-#ifdef CAML_INTERNALS
-value caml_input_val (struct channel * chan);
-  /* Read a structured value from the channel [chan]. */
-#endif /* CAML_INTERNALS */
-
 CAMLextern value caml_input_val_from_string (value str, intnat ofs);
   /* Read a structured value from the OCaml string [str], starting
      at offset [ofs]. */

runtime/caml/minor_gc.h

@@ -39,6 +39,10 @@
   asize_t reserve;             \
 }
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Count of the total number of minor collections performed by the program */
 CAMLextern atomic_uintnat caml_minor_collections_count;
 
@@ -69,6 +73,10 @@ struct caml_minor_tables {
 
 CAMLextern void caml_minor_collection (void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #ifdef CAML_INTERNALS
 extern void caml_set_minor_heap_size (asize_t); /* size in bytes */
 extern void caml_empty_minor_heap_no_major_slice_from_stw

runtime/caml/osdeps.h

@@ -18,15 +18,6 @@
 #ifndef CAML_OSDEPS_H
 #define CAML_OSDEPS_H
 
-#ifdef _WIN32
-#include <time.h>
-
-extern unsigned short caml_win32_major;
-extern unsigned short caml_win32_minor;
-extern unsigned short caml_win32_build;
-extern unsigned short caml_win32_revision;
-#endif
-
 #ifdef CAML_INTERNALS
 
 #include "misc.h"
@@ -139,12 +130,14 @@ CAMLextern int caml_win32_isatty(int fd);
 
 CAMLextern void caml_expand_command_line (int *, wchar_t ***);
 
-CAMLextern clock_t caml_win32_clock(void);
-
 CAMLextern value caml_win32_xdg_defaults(void);
 
 CAMLextern value caml_win32_get_temp_path(void);
 
+#include <time.h>
+
+CAMLextern clock_t caml_win32_clock(void);
+
 #endif /* _WIN32 */
 
 /* Returns the current value of a counter that increments once per nanosecond.
@@ -162,6 +155,15 @@ extern void caml_init_os_params(void);
 
 #ifdef _WIN32
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern unsigned short caml_win32_major;
+extern unsigned short caml_win32_minor;
+extern unsigned short caml_win32_build;
+extern unsigned short caml_win32_revision;
+
 /* [caml_stat_strdup_to_utf16(s)] returns a null-terminated copy of [s],
    re-encoded in UTF-16.  The encoding of [s] is assumed to be UTF-8 if
    [caml_windows_unicode_runtime_enabled] is non-zero **and** [s] is valid
@@ -200,6 +202,10 @@ CAMLextern char* caml_stat_strdup_of_utf16(const wchar_t *s);
 */
 CAMLextern value caml_copy_string_of_utf16(const wchar_t *s);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _WIN32 */
 
 #endif /* CAML_OSDEPS_H */

runtime/caml/printexc.h

@@ -23,14 +23,14 @@
 extern "C" {
 #endif
 
-
 CAMLextern char * caml_format_exception (value);
-#ifdef CAML_INTERNALS
-CAMLnoret void caml_fatal_uncaught_exception (value);
-#endif /* CAML_INTERNALS */
 
 #ifdef __cplusplus
 }
 #endif
 
+#ifdef CAML_INTERNALS
+CAMLnoret void caml_fatal_uncaught_exception (value);
+#endif /* CAML_INTERNALS */
+
 #endif /* CAML_PRINTEXC_H */

runtime/caml/runtime_events.h

@@ -176,6 +176,10 @@ typedef enum {
   E_CURSOR_POLL_BUSY = -8,
 } runtime_events_error;
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Starts runtime_events. Needs to be called before
    [caml_runtime_events_create_cursor]. Needs the runtime lock held to call and
    will trigger a stop-the-world pause. */
@@ -197,6 +201,10 @@ CAMLextern void caml_runtime_events_resume(void);
    [0] otherwise. */
 CAMLextern int caml_runtime_events_are_active(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #ifdef CAML_INTERNALS
 
 struct runtime_events_buffer_header {

runtime/caml/signals.h

@@ -46,6 +46,13 @@ CAMLextern caml_result caml_process_pending_actions_res (void);
    kept around for compatibility. */
 CAMLextern value caml_process_pending_actions_exn (void);
 
+CAMLextern int caml_check_pending_actions (void);
+/* Returns 1 if there are pending actions, 0 otherwise. */
+
+#ifdef __cplusplus
+}
+#endif
+
 #ifdef CAML_INTERNALS
 
 value caml_process_pending_actions_with_root (value extra_root); // raises
@@ -72,12 +79,6 @@ value caml_process_pending_actions_with_root (value extra_root); // raises
 */
 
 caml_result caml_process_pending_actions_with_root_res (value extra_root);
-#endif
-
-CAMLextern int caml_check_pending_actions (void);
-/* Returns 1 if there are pending actions, 0 otherwise. */
-
-#ifdef CAML_INTERNALS
 
 #ifndef NSIG
 #define NSIG 65
@@ -112,10 +113,7 @@ CAMLextern void caml_free_signal_stack(void *);
 /* These hooks are not modified after other threads are spawned. */
 CAMLextern void (*caml_enter_blocking_section_hook)(void);
 CAMLextern void (*caml_leave_blocking_section_hook)(void);
-#endif /* CAML_INTERNALS */
 
-#ifdef __cplusplus
-}
-#endif
+#endif /* CAML_INTERNALS */
 
 #endif /* CAML_SIGNALS_H */

runtime/caml/sys.h

@@ -20,10 +20,6 @@
 
 #include "misc.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 CAMLextern char * caml_strerror(int errnum, char * buf, size_t buflen);
 
 #define NO_ARG Val_int(0)
@@ -37,10 +33,6 @@ CAMLextern void caml_sys_init (const char_os * exe_name, char_os ** argv);
 
 CAMLnoret CAMLextern void caml_do_exit (int);
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* CAML_INTERNALS */
 
 #endif /* CAML_SYS_H */

runtime/caml/tsan.h

@@ -15,6 +15,10 @@
 #ifndef CAML_TSAN_H
 #define CAML_TSAN_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Macro used to deactivate thread sanitizer on some functions. */
 #define CAMLno_tsan
 /* `__has_feature` is present in Clang and recent GCCs (14 and later). Older
@@ -72,6 +76,9 @@ extern void AnnotateHappensAfter(const char *f, int l, void *addr);
 #  define CAMLno_tsan_for_perf CAMLno_tsan
 #endif
 
+#ifdef __cplusplus
+}
+#endif
 
 #ifdef CAML_INTERNALS