Rethink the generation rule for fmgroids.h macros.

Traditionally, the names of fmgroids.h macros for pg_proc OIDs
have been constructed from the prosrc field.  But sometimes the
same C function underlies multiple pg_proc entries, forcing us
to make an arbitrary choice of which OID to reference; the other
entries are then not namable via fmgroids.h.  Moreover, we could
not have macros at all for pg_proc entries that aren't for
C-coded functions.

Instead, use the proname field, and append the proargtypes field
(replacing inter-argument spaces with underscores) if proname is
not unique.  Special-casing unique entries such as F_OIDEQ removes
the need to change a lot of code.  Indeed, I can only find two
places in the tree that need to be adjusted; while this changes
quite a few existing entries in fmgroids.h, few of them are
referenced from C code.

With this patch, all entries in pg_proc.dat have macros in fmgroids.h.

Discussion: https://postgr.es/m/472274.1604258384@sss.pgh.pa.us

src/backend/optimizer/util/clauses.c

@@ -779,7 +779,7 @@ contain_volatile_functions_not_nextval(Node *clause)
 static bool
 contain_volatile_functions_not_nextval_checker(Oid func_id, void *context)
 {
-	return (func_id != F_NEXTVAL_OID &&
+	return (func_id != F_NEXTVAL &&
 			func_volatile(func_id) == PROVOLATILE_VOLATILE);
 }
 

src/backend/utils/Gen_fmgrtab.pl

@@ -64,22 +64,26 @@ foreach my $datfile (@ARGV)
 
 # Collect certain fields from pg_proc.dat.
 my @fmgr = ();
+my %proname_counts;
 
 foreach my $row (@{ $catalog_data{pg_proc} })
 {
 	my %bki_values = %$row;
 
-	# Select out just the rows for internal-language procedures.
-	next if $bki_values{prolang} ne 'internal';
-
 	push @fmgr,
 	  {
 		oid    => $bki_values{oid},
+		name   => $bki_values{proname},
+		lang   => $bki_values{prolang},
 		strict => $bki_values{proisstrict},
 		retset => $bki_values{proretset},
 		nargs  => $bki_values{pronargs},
+		args   => $bki_values{proargtypes},
 		prosrc => $bki_values{prosrc},
 	  };
+
+	# Count so that we can detect overloaded pronames.
+	$proname_counts{ $bki_values{proname} }++;
 }
 
 # Emit headers for both files
@@ -122,13 +126,10 @@ print $ofh <<OFH;
 /*
  *	Constant macros for the OIDs of entries in pg_proc.
  *
- *	NOTE: macros are named after the prosrc value, ie the actual C name
- *	of the implementing function, not the proname which may be overloaded.
- *	For example, we want to be able to assign different macro names to both
- *	char_text() and name_text() even though these both appear with proname
- *	'text'.  If the same C function appears in more than one pg_proc entry,
- *	its equivalent macro will be defined with the lowest OID among those
- *	entries.
+ *	F_XXX macros are named after the proname field; if that is not unique,
+ *	we append the proargtypes field, replacing spaces with underscores.
+ *	For example, we have F_OIDEQ because that proname is unique, but
+ *	F_POW_FLOAT8_FLOAT8 (among others) because that proname is not.
  */
 OFH
 
@@ -186,14 +187,20 @@ print $tfh <<TFH;
 
 TFH
 
-# Emit #define's and extern's -- only one per prosrc value
+# Emit fmgroids.h and fmgrprotos.h entries in OID order.
 my %seenit;
 foreach my $s (sort { $a->{oid} <=> $b->{oid} } @fmgr)
 {
-	next if $seenit{ $s->{prosrc} };
-	$seenit{ $s->{prosrc} } = 1;
-	print $ofh "#define F_" . uc $s->{prosrc} . " $s->{oid}\n";
-	print $pfh "extern Datum $s->{prosrc}(PG_FUNCTION_ARGS);\n";
+	my $sqlname = $s->{name};
+	$sqlname .= "_" . $s->{args} if ($proname_counts{ $s->{name} } > 1);
+	$sqlname =~ s/\s+/_/g;
+	print $ofh "#define F_" . uc $sqlname . " $s->{oid}\n";
+	# We want only one extern per internal-language function
+	if ($s->{lang} eq 'internal' && !$seenit{ $s->{prosrc} })
+	{
+		$seenit{ $s->{prosrc} } = 1;
+		print $pfh "extern Datum $s->{prosrc}(PG_FUNCTION_ARGS);\n";
+	}
 }
 
 # Create the fmgr_builtins table, collect data for fmgr_builtin_oid_index
@@ -206,22 +213,16 @@ my $last_builtin_oid = 0;
 my $fmgr_count       = 0;
 foreach my $s (sort { $a->{oid} <=> $b->{oid} } @fmgr)
 {
+	next if $s->{lang} ne 'internal';
+
+	print $tfh ",\n" if ($fmgr_count > 0);
 	print $tfh
 	  "  { $s->{oid}, $s->{nargs}, $bmap{$s->{strict}}, $bmap{$s->{retset}}, \"$s->{prosrc}\", $s->{prosrc} }";
 
 	$fmgr_builtin_oid_index[ $s->{oid} ] = $fmgr_count++;
 	$last_builtin_oid = $s->{oid};
-
-	if ($fmgr_count <= $#fmgr)
-	{
-		print $tfh ",\n";
-	}
-	else
-	{
-		print $tfh "\n";
-	}
 }
-print $tfh "};\n";
+print $tfh "\n};\n";
 
 printf $tfh qq|
 const int fmgr_nbuiltins = (sizeof(fmgr_builtins) / sizeof(FmgrBuiltin));

src/backend/utils/adt/ruleutils.c

@@ -10144,7 +10144,7 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 						RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
 
 						if (!IsA(rtfunc->funcexpr, FuncExpr) ||
-							((FuncExpr *) rtfunc->funcexpr)->funcid != F_ARRAY_UNNEST ||
+							((FuncExpr *) rtfunc->funcexpr)->funcid != F_UNNEST_ANYARRAY ||
 							rtfunc->funccolnames != NIL)
 						{
 							all_unnest = false;