Create function prototype as part of PG_FUNCTION_INFO_V1 macro

Because of gcc -Wmissing-prototypes, all functions in dynamically
loadable modules must have a separate prototype declaration.  This is
meant to detect global functions that are not declared in header files,
but in cases where the function is called via dfmgr, this is redundant.
Besides filling up space with boilerplate, this is a frequent source of
compiler warnings in extension modules.

We can fix that by creating the function prototype as part of the
PG_FUNCTION_INFO_V1 macro, which such modules have to use anyway.  That
makes the code of modules cleaner, because there is one less place where
the entry points have to be listed, and creates an additional check that
functions have the right prototype.

Remove now redundant prototypes from contrib and other modules.

src/include/fmgr.h

@@ -348,6 +348,7 @@ typedef const Pg_finfo_record *(*PGFInfoFunction) (void);
  *	doesn't hurt to add PGDLLIMPORT in case they don't.
  */
 #define PG_FUNCTION_INFO_V1(funcname) \
+Datum funcname(PG_FUNCTION_ARGS); \
 extern PGDLLEXPORT const Pg_finfo_record * CppConcat(pg_finfo_,funcname)(void); \
 const Pg_finfo_record * \
 CppConcat(pg_finfo_,funcname) (void) \

src/pl/plperl/plperl.c

@@ -240,12 +240,6 @@ static plperl_call_data *current_call_data = NULL;
 /**********************************************************************
  * Forward declarations
  **********************************************************************/
-Datum		plperl_call_handler(PG_FUNCTION_ARGS);
-Datum		plperl_inline_handler(PG_FUNCTION_ARGS);
-Datum		plperl_validator(PG_FUNCTION_ARGS);
-Datum		plperlu_call_handler(PG_FUNCTION_ARGS);
-Datum		plperlu_inline_handler(PG_FUNCTION_ARGS);
-Datum		plperlu_validator(PG_FUNCTION_ARGS);
 void		_PG_init(void);
 
 static PerlInterpreter *plperl_init_interp(void);

src/pl/plpgsql/src/plpgsql.h

@@ -950,9 +950,6 @@ extern void plpgsql_HashTableInit(void);
  * ----------
  */
 extern void _PG_init(void);
-extern Datum plpgsql_call_handler(PG_FUNCTION_ARGS);
-extern Datum plpgsql_inline_handler(PG_FUNCTION_ARGS);
-extern Datum plpgsql_validator(PG_FUNCTION_ARGS);
 
 /* ----------
  * Functions in pl_exec.c

src/pl/plpython/plpy_main.c

@@ -40,16 +40,6 @@
 #endif
 
 extern void _PG_init(void);
-extern Datum plpython_validator(PG_FUNCTION_ARGS);
-extern Datum plpython_call_handler(PG_FUNCTION_ARGS);
-extern Datum plpython_inline_handler(PG_FUNCTION_ARGS);
-
-#if PY_MAJOR_VERSION < 3
-/* Define aliases plpython2_call_handler etc */
-extern Datum plpython2_validator(PG_FUNCTION_ARGS);
-extern Datum plpython2_call_handler(PG_FUNCTION_ARGS);
-extern Datum plpython2_inline_handler(PG_FUNCTION_ARGS);
-#endif
 
 PG_MODULE_MAGIC;
 
@@ -58,6 +48,7 @@ PG_FUNCTION_INFO_V1(plpython_call_handler);
 PG_FUNCTION_INFO_V1(plpython_inline_handler);
 
 #if PY_MAJOR_VERSION < 3
+/* Define aliases plpython2_call_handler etc */
 PG_FUNCTION_INFO_V1(plpython2_validator);
 PG_FUNCTION_INFO_V1(plpython2_call_handler);
 PG_FUNCTION_INFO_V1(plpython2_inline_handler);

src/pl/tcl/pltcl.c

@@ -192,8 +192,6 @@ static pltcl_proc_desc *pltcl_current_prodesc = NULL;
 /**********************************************************************
  * Forward declarations
  **********************************************************************/
-Datum		pltcl_call_handler(PG_FUNCTION_ARGS);
-Datum		pltclu_call_handler(PG_FUNCTION_ARGS);
 void		_PG_init(void);
 
 static void pltcl_init_interp(pltcl_interp_desc *interp_desc, bool pltrusted);

src/test/regress/regress.c

@@ -28,18 +28,10 @@
 #define RDELIM			')'
 #define DELIM			','
 
-extern Datum regress_dist_ptpath(PG_FUNCTION_ARGS);
-extern Datum regress_path_dist(PG_FUNCTION_ARGS);
 extern PATH *poly2path(POLYGON *poly);
-extern Datum interpt_pp(PG_FUNCTION_ARGS);
 extern void regress_lseg_construct(LSEG *lseg, Point *pt1, Point *pt2);
-extern Datum overpaid(PG_FUNCTION_ARGS);
-extern Datum boxarea(PG_FUNCTION_ARGS);
 extern char *reverse_name(char *string);
 extern int	oldstyle_length(int n, text *t);
-extern Datum int44in(PG_FUNCTION_ARGS);
-extern Datum int44out(PG_FUNCTION_ARGS);
-extern Datum make_tuple_indirect(PG_FUNCTION_ARGS);
 
 #ifdef PG_MODULE_MAGIC
 PG_MODULE_MAGIC;
@@ -236,7 +228,6 @@ typedef struct
 
 WIDGET	   *widget_in(char *str);
 char	   *widget_out(WIDGET * widget);
-extern Datum pt_in_widget(PG_FUNCTION_ARGS);
 
 #define NARGS	3
 
@@ -341,7 +332,6 @@ static int	fd17b_level = 0;
 static int	fd17a_level = 0;
 static bool fd17b_recursion = true;
 static bool fd17a_recursion = true;
-extern Datum funny_dup17(PG_FUNCTION_ARGS);
 
 PG_FUNCTION_INFO_V1(funny_dup17);
 
@@ -453,9 +443,6 @@ funny_dup17(PG_FUNCTION_ARGS)
 	return PointerGetDatum(tuple);
 }
 
-extern Datum ttdummy(PG_FUNCTION_ARGS);
-extern Datum set_ttdummy(PG_FUNCTION_ARGS);
-
 #define TTDUMMY_INFINITY	999999
 
 static SPIPlanPtr splan = NULL;