dbug: correct trace for DBUG_RETURN(func()); -- gcc only

when func1 calls func2 from DBUG_RETURN, dbug shows the trace as
| > func1
| < func1
| > func2
| < func2
because DBUG_LEAVE happens before func2(). Change that to invoke
DBUG_LEAVE when the local variable goes out of scope. This uses
gcc specific __attribute__((cleanup)).

cmake/os/WindowsCache.cmake

@@ -320,6 +320,7 @@ IF(MSVC_VERSION GREATER 1310)
 SET(HAVE_VSNPRINTF 1 CACHE  INTERNAL "")
 ENDIF()
 SET(HAVE_WEAK_SYMBOL CACHE  INTERNAL "")
+SET(HAVE_ATTRIBUTE_CLEANUP CACHE  INTERNAL "")
 SET(HAVE_WORDS_BIGENDIAN TRUE CACHE  INTERNAL "")
 SET(WORDS_BIGENDIAN CACHE  INTERNAL "")
 SET(HAVE__S_IFIFO 1 CACHE  INTERNAL "")

config.h.cmake

@@ -465,7 +465,7 @@
 
 #cmakedefine HAVE_WEAK_SYMBOL 1
 #cmakedefine HAVE_ABI_CXA_DEMANGLE 1
-
+#cmakedefine HAVE_ATTRIBUTE_CLEANUP 1
 
 #cmakedefine HAVE_POSIX_SIGNALS 1
 #cmakedefine HAVE_BSD_SIGNALS 1

configure.cmake

@@ -910,6 +910,14 @@ CHECK_C_SOURCE_COMPILES("
     HAVE_WEAK_SYMBOL
 )
 
+CHECK_C_SOURCE_COMPILES("
+    void foo(int *x) { }
+    int main() {
+      int a __attribute__((cleanup(foo)));
+      return 0;
+    }"
+    HAVE_ATTRIBUTE_CLEANUP
+)
 
 CHECK_CXX_SOURCE_COMPILES("
     #include <new>

dbug/dbug.c

@@ -1106,6 +1106,7 @@ void _db_enter_(const char *_func_, const char *_file_,
   }
   save_errno= errno;
 
+  _stack_frame_->line= -1;
   _stack_frame_->func= cs->func;
   _stack_frame_->file= cs->file;
   cs->func=  _func_;
@@ -1161,14 +1162,17 @@ void _db_enter_(const char *_func_, const char *_file_,
  *
  */
 
-void _db_return_(uint _line_, struct _db_stack_frame_ *_stack_frame_)
+void _db_return_(struct _db_stack_frame_ *_stack_frame_)
 {
   int save_errno=errno;
   uint _slevel_= _stack_frame_->level & ~TRACE_ON;
   CODE_STATE *cs;
   get_code_state_or_return;
 
-  if (cs->framep != _stack_frame_)
+  if (_stack_frame_->line == 0)
+    return;
+
+  if (_stack_frame_->line == -1 || cs->framep != _stack_frame_)
   {
     char buf[512];
     my_snprintf(buf, sizeof(buf), ERR_MISSING_RETURN, cs->func);
@@ -1183,7 +1187,7 @@ void _db_return_(uint _line_, struct _db_stack_frame_ *_stack_frame_)
     {
       if (!cs->locked)
         pthread_mutex_lock(&THR_LOCK_dbug);
-      DoPrefix(cs, _line_);
+      DoPrefix(cs, _stack_frame_->line);
       Indent(cs, cs->level);
       (void) fprintf(cs->stack->out_file->file, "<%s\n", cs->func);
       DbugFlush(cs);

include/my_dbug.h

@@ -30,6 +30,7 @@ struct _db_stack_frame_ {
   const char *func;      /* function name of the previous stack frame       */
   const char *file;      /* filename of the function of previous frame      */
   uint level;            /* this nesting level, highest bit enables tracing */
+  int line;              /* line of DBUG_RETURN                             */
   struct _db_stack_frame_ *prev; /* pointer to the previous frame */
 };
 
@@ -48,7 +49,7 @@ extern  void _db_set_(const char *control);
 extern  void _db_set_init_(const char *control);
 extern void _db_enter_(const char *_func_, const char *_file_, uint _line_,
                        struct _db_stack_frame_ *_stack_frame_);
-extern  void _db_return_(uint _line_, struct _db_stack_frame_ *_stack_frame_);
+extern  void _db_return_(struct _db_stack_frame_ *_stack_frame_);
 extern  void _db_pargs_(uint _line_,const char *keyword);
 extern  void _db_doprnt_(const char *format,...)
   ATTRIBUTE_FORMAT(printf, 1, 2);
@@ -63,12 +64,24 @@ extern void dbug_swap_code_state(void **code_state_store);
 extern void dbug_free_code_state(void **code_state_store);
 extern  const char* _db_get_func_(void);
 
+#define DBUG_LEAVE do { \
+    _db_stack_frame_.line= __LINE__; \
+    _db_return_ (&_db_stack_frame_); \
+    _db_stack_frame_.line= 0; \
+  } while(0)
+
+#ifdef HAVE_ATTRIBUTE_CLEANUP
+#define DBUG_ENTER(a) struct _db_stack_frame_ _db_stack_frame_  __attribute__((cleanup(_db_return_))); \
+        _db_enter_ (a,__FILE__,__LINE__,&_db_stack_frame_)
+#define DBUG_RETURN(a1) do { _db_stack_frame_.line=__LINE__; return(a1);} while(0)
+#define DBUG_VOID_RETURN do { _db_stack_frame_.line=__LINE__; return;} while(0)
+#else
 #define DBUG_ENTER(a) struct _db_stack_frame_ _db_stack_frame_; \
         _db_enter_ (a,__FILE__,__LINE__,&_db_stack_frame_)
-#define DBUG_LEAVE _db_return_ (__LINE__, &_db_stack_frame_)
-
 #define DBUG_RETURN(a1) do {DBUG_LEAVE; return(a1);} while(0)
 #define DBUG_VOID_RETURN do {DBUG_LEAVE; return;} while(0)
+#endif
+
 #define DBUG_EXECUTE(keyword,a1) \
         do {if (_db_keyword_(0, (keyword), 0)) { a1 }} while(0)
 #define DBUG_EXECUTE_IF(keyword,a1) \