Rely on __func__ being supported

Previously we fell back to __FUNCTION__ and then NULL. As __func__ is in C99
that shouldn't be necessary anymore.

Solution.pm defined HAVE_FUNCNAME__FUNCTION instead of
HAVE_FUNCNAME__FUNC (originating in 4164e6636e2), as at some point in the past
MSVC only supported __FUNCTION__. Our minimum version supports __func__.

Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220807012914.ydz73yte6j3coulo@awork3.anarazel.de

config/c-compiler.m4

@@ -165,32 +165,6 @@ if (q != holder)
 fi])# PGAC_TYPE_128BIT_INT
 
 
-# PGAC_C_FUNCNAME_SUPPORT
-# -----------------------
-# Check if the C compiler understands __func__ (C99) or __FUNCTION__ (gcc).
-# Define HAVE_FUNCNAME__FUNC or HAVE_FUNCNAME__FUNCTION accordingly.
-AC_DEFUN([PGAC_C_FUNCNAME_SUPPORT],
-[AC_CACHE_CHECK(for __func__, pgac_cv_funcname_func_support,
-[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>],
-[printf("%s\n", __func__);])],
-[pgac_cv_funcname_func_support=yes],
-[pgac_cv_funcname_func_support=no])])
-if test x"$pgac_cv_funcname_func_support" = xyes ; then
-AC_DEFINE(HAVE_FUNCNAME__FUNC, 1,
-          [Define to 1 if your compiler understands __func__.])
-else
-AC_CACHE_CHECK(for __FUNCTION__, pgac_cv_funcname_function_support,
-[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>],
-[printf("%s\n", __FUNCTION__);])],
-[pgac_cv_funcname_function_support=yes],
-[pgac_cv_funcname_function_support=no])])
-if test x"$pgac_cv_funcname_function_support" = xyes ; then
-AC_DEFINE(HAVE_FUNCNAME__FUNCTION, 1,
-          [Define to 1 if your compiler understands __FUNCTION__.])
-fi
-fi])# PGAC_C_FUNCNAME_SUPPORT
-
-
 
 # PGAC_C_STATIC_ASSERT
 # --------------------

configure

@@ -14937,67 +14937,6 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __func__" >&5
-$as_echo_n "checking for __func__... " >&6; }
-if ${pgac_cv_funcname_func_support+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <stdio.h>
-int
-main ()
-{
-printf("%s\n", __func__);
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv_funcname_func_support=yes
-else
-  pgac_cv_funcname_func_support=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_funcname_func_support" >&5
-$as_echo "$pgac_cv_funcname_func_support" >&6; }
-if test x"$pgac_cv_funcname_func_support" = xyes ; then
-
-$as_echo "#define HAVE_FUNCNAME__FUNC 1" >>confdefs.h
-
-else
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __FUNCTION__" >&5
-$as_echo_n "checking for __FUNCTION__... " >&6; }
-if ${pgac_cv_funcname_function_support+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <stdio.h>
-int
-main ()
-{
-printf("%s\n", __FUNCTION__);
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv_funcname_function_support=yes
-else
-  pgac_cv_funcname_function_support=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_funcname_function_support" >&5
-$as_echo "$pgac_cv_funcname_function_support" >&6; }
-if test x"$pgac_cv_funcname_function_support" = xyes ; then
-
-$as_echo "#define HAVE_FUNCNAME__FUNCTION 1" >>confdefs.h
-
-fi
-fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for _Static_assert" >&5
 $as_echo_n "checking for _Static_assert... " >&6; }
 if ${pgac_cv__static_assert+:} false; then :

configure.ac

@@ -1635,7 +1635,6 @@ m4_defun([AC_PROG_CC_STDC], []) dnl We don't want that.
 AC_C_BIGENDIAN
 AC_C_INLINE
 PGAC_PRINTF_ARCHETYPE
-PGAC_C_FUNCNAME_SUPPORT
 PGAC_C_STATIC_ASSERT
 PGAC_C_TYPEOF
 PGAC_C_TYPES_COMPATIBLE

src/backend/storage/lmgr/s_lock.c

@@ -304,7 +304,7 @@ main()
 	printf("             if S_LOCK() and TAS() are working.\n");
 	fflush(stdout);
 
-	s_lock(&test_lock.lock, __FILE__, __LINE__, PG_FUNCNAME_MACRO);
+	s_lock(&test_lock.lock, __FILE__, __LINE__, __func__);
 
 	printf("S_LOCK_TEST: failed, lock not locked\n");
 	return 1;

src/include/c.h

@@ -360,17 +360,6 @@ typedef void (*pg_funcptr_t) (void);
  */
 #define FLEXIBLE_ARRAY_MEMBER	/* empty */
 
-/* Which __func__ symbol do we have, if any? */
-#ifdef HAVE_FUNCNAME__FUNC
-#define PG_FUNCNAME_MACRO	__func__
-#else
-#ifdef HAVE_FUNCNAME__FUNCTION
-#define PG_FUNCNAME_MACRO	__FUNCTION__
-#else
-#define PG_FUNCNAME_MACRO	NULL
-#endif
-#endif
-
 
 /* ----------------------------------------------------------------
  *				Section 2:	bool, true, false

src/include/pg_config.h.in

@@ -158,12 +158,6 @@
 /* Define to 1 if fseeko (and presumably ftello) exists and is declared. */
 #undef HAVE_FSEEKO
 
-/* Define to 1 if your compiler understands __func__. */
-#undef HAVE_FUNCNAME__FUNC
-
-/* Define to 1 if your compiler understands __FUNCTION__. */
-#undef HAVE_FUNCNAME__FUNCTION
-
 /* Define to 1 if you have __atomic_compare_exchange_n(int *, int *, int). */
 #undef HAVE_GCC__ATOMIC_INT32_CAS
 

src/include/storage/s_lock.h

@@ -768,7 +768,7 @@ extern int	tas_sema(volatile slock_t *lock);
 
 #if !defined(S_LOCK)
 #define S_LOCK(lock) \
-	(TAS(lock) ? s_lock((lock), __FILE__, __LINE__, PG_FUNCNAME_MACRO) : 0)
+	(TAS(lock) ? s_lock((lock), __FILE__, __LINE__, __func__) : 0)
 #endif	 /* S_LOCK */
 
 #if !defined(S_LOCK_FREE)
@@ -855,7 +855,7 @@ init_spin_delay(SpinDelayStatus *status,
 	status->func = func;
 }
 
-#define init_local_spin_delay(status) init_spin_delay(status, __FILE__, __LINE__, PG_FUNCNAME_MACRO)
+#define init_local_spin_delay(status) init_spin_delay(status, __FILE__, __LINE__, __func__)
 extern void perform_spin_delay(SpinDelayStatus *status);
 extern void finish_spin_delay(SpinDelayStatus *status);
 

src/include/utils/elog.h

@@ -140,7 +140,7 @@
 		if (__builtin_constant_p(elevel) && (elevel) >= ERROR ? \
 			errstart_cold(elevel, domain) : \
 			errstart(elevel, domain)) \
-			__VA_ARGS__, errfinish(__FILE__, __LINE__, PG_FUNCNAME_MACRO); \
+			__VA_ARGS__, errfinish(__FILE__, __LINE__, __func__); \
 		if (__builtin_constant_p(elevel) && (elevel) >= ERROR) \
 			pg_unreachable(); \
 	} while(0)
@@ -150,7 +150,7 @@
 		const int elevel_ = (elevel); \
 		pg_prevent_errno_in_scope(); \
 		if (errstart(elevel_, domain)) \
-			__VA_ARGS__, errfinish(__FILE__, __LINE__, PG_FUNCNAME_MACRO); \
+			__VA_ARGS__, errfinish(__FILE__, __LINE__, __func__); \
 		if (elevel_ >= ERROR) \
 			pg_unreachable(); \
 	} while(0)

src/tools/msvc/Solution.pm

@@ -250,8 +250,6 @@ sub GenerateFiles
 		HAVE_EXECINFO_H                             => undef,
 		HAVE_EXPLICIT_BZERO                         => undef,
 		HAVE_FSEEKO                                 => 1,
-		HAVE_FUNCNAME__FUNC                         => undef,
-		HAVE_FUNCNAME__FUNCTION                     => 1,
 		HAVE_GCC__ATOMIC_INT32_CAS                  => undef,
 		HAVE_GCC__ATOMIC_INT64_CAS                  => undef,
 		HAVE_GCC__SYNC_CHAR_TAS                     => undef,