Build all Flex files standalone

The proposed Meson build system will need a way to ignore certain
generated files in order to coexist with the autoconf build system,
and C files generated by Flex which are #include'd into .y files make
this more difficult. In similar vein to 72b1e3a21, arrange for all Flex
C files to compile to their own .o targets.

Reviewed by Andres Freund

Discussion: https://www.postgresql.org/message-id/20220810171935.7k5zgnjwqzalzmtm%40awork3.anarazel.de
Discussion: https://www.postgresql.org/message-id/CAFBsxsF8Gc2StS3haXofshHCzqNMRXiSxvQEYGwnFsTmsdwNeg@mail.gmail.com

src/backend/replication/.gitignore

@@ -1,4 +1,6 @@
+/repl_gram.h
 /repl_gram.c
 /repl_scanner.c
+/syncrep_gram.h
 /syncrep_gram.c
 /syncrep_scanner.c

src/backend/replication/Makefile

@@ -16,10 +16,12 @@ override CPPFLAGS := -I. -I$(srcdir) $(CPPFLAGS)
 
 OBJS = \
 	repl_gram.o \
+	repl_scanner.o \
 	slot.o \
 	slotfuncs.o \
 	syncrep.o \
 	syncrep_gram.o \
+	syncrep_scanner.o \
 	walreceiver.o \
 	walreceiverfuncs.o \
 	walsender.o
@@ -28,11 +30,23 @@ SUBDIRS = logical
 
 include $(top_srcdir)/src/backend/common.mk
 
-# repl_scanner is compiled as part of repl_gram
-repl_gram.o: repl_scanner.c
+# See notes in src/backend/parser/Makefile about the following two rules
+repl_gram.h: repl_gram.c
+	touch $@
 
-# syncrep_scanner is compiled as part of syncrep_gram
-syncrep_gram.o: syncrep_scanner.c
+repl_gram.c: BISONFLAGS += -d
+
+# Force these dependencies to be known even without dependency info built:
+repl_gram.o repl_scanner.o: repl_gram.h
+
+# See notes in src/backend/parser/Makefile about the following two rules
+syncrep_gram.h: syncrep_gram.c
+	touch $@
+
+syncrep_gram.c: BISONFLAGS += -d
+
+# Force these dependencies to be known even without dependency info built:
+syncrep_gram.o syncrep_scanner.o: syncrep_gram.h
 
 # repl_gram.c, repl_scanner.c, syncrep_gram.c and syncrep_scanner.c
 # are in the distribution tarball, so they are not cleaned here.

src/backend/replication/repl_gram.y

@@ -416,5 +416,3 @@ ident_or_keyword:
 		;
 
 %%
-
-#include "repl_scanner.c"

src/backend/replication/repl_scanner.l

@@ -1,4 +1,4 @@
-%{
+%top{
 /*-------------------------------------------------------------------------
  *
  * repl_scanner.l
@@ -18,6 +18,15 @@
 #include "utils/builtins.h"
 #include "parser/scansup.h"
 
+/*
+ * NB: include repl_gram.h only AFTER including walsender_private.h, because
+ * walsender_private includes headers that define XLogRecPtr.
+ */
+#include "replication/walsender_private.h"
+#include "repl_gram.h"
+}
+
+%{
 /* Avoid exit() on fatal scanner errors (a bit ugly -- see yy_fatal_error) */
 #undef fprintf
 #define fprintf(file, fmt, msg)  fprintf_to_ereport(fmt, msg)
@@ -130,7 +139,7 @@ WAIT				{ return K_WAIT; }
 {space}+		{ /* do nothing */ }
 
 {digit}+		{
-					yylval.uintval = strtoul(yytext, NULL, 10);
+					replication_yylval.uintval = strtoul(yytext, NULL, 10);
 					return UCONST;
 				}
 
@@ -138,8 +147,8 @@ WAIT				{ return K_WAIT; }
 					uint32	hi,
 							lo;
 					if (sscanf(yytext, "%X/%X", &hi, &lo) != 2)
-						yyerror("invalid streaming start location");
-					yylval.recptr = ((uint64) hi) << 32 | lo;
+						replication_yyerror("invalid streaming start location");
+					replication_yylval.recptr = ((uint64) hi) << 32 | lo;
 					return RECPTR;
 				}
 
@@ -151,7 +160,7 @@ WAIT				{ return K_WAIT; }
 <xq>{quotestop}	{
 					yyless(1);
 					BEGIN(INITIAL);
-					yylval.str = litbufdup();
+					replication_yylval.str = litbufdup();
 					return SCONST;
 				}
 
@@ -173,9 +182,9 @@ WAIT				{ return K_WAIT; }
 
 					yyless(1);
 					BEGIN(INITIAL);
-					yylval.str = litbufdup();
-					len = strlen(yylval.str);
-					truncate_identifier(yylval.str, len, true);
+					replication_yylval.str = litbufdup();
+					len = strlen(replication_yylval.str);
+					truncate_identifier(replication_yylval.str, len, true);
 					return IDENT;
 				}
 
@@ -186,7 +195,7 @@ WAIT				{ return K_WAIT; }
 {identifier}	{
 					int			len = strlen(yytext);
 
-					yylval.str = downcase_truncate_identifier(yytext, len, true);
+					replication_yylval.str = downcase_truncate_identifier(yytext, len, true);
 					return IDENT;
 				}
 
@@ -195,7 +204,7 @@ WAIT				{ return K_WAIT; }
 					return yytext[0];
 				}
 
-<xq,xd><<EOF>>	{ yyerror("unterminated quoted string"); }
+<xq,xd><<EOF>>	{ replication_yyerror("unterminated quoted string"); }
 
 
 <<EOF>>			{
@@ -231,7 +240,7 @@ addlitchar(unsigned char ychar)
 }
 
 void
-yyerror(const char *message)
+replication_yyerror(const char *message)
 {
 	ereport(ERROR,
 			(errcode(ERRCODE_SYNTAX_ERROR),

src/backend/replication/syncrep_gram.y

@@ -112,5 +112,3 @@ create_syncrep_config(const char *num_sync, List *members, uint8 syncrep_method)
 
 	return config;
 }
-
-#include "syncrep_scanner.c"

src/backend/replication/syncrep_scanner.l

@@ -1,4 +1,4 @@
-%{
+%top{
 /*-------------------------------------------------------------------------
  *
  * syncrep_scanner.l
@@ -17,6 +17,15 @@
 
 #include "lib/stringinfo.h"
 
+/*
+ * NB: include syncrep_gram.h only AFTER including syncrep.h, because syncrep.h
+ * includes node definitions needed for YYSTYPE.
+ */
+#include "replication/syncrep.h"
+#include "syncrep_gram.h"
+}
+
+%{
 /* Avoid exit() on fatal scanner errors (a bit ugly -- see yy_fatal_error) */
 #undef fprintf
 #define fprintf(file, fmt, msg)  fprintf_to_ereport(fmt, msg)
@@ -82,28 +91,28 @@ xdinside		[^"]+
 				appendStringInfoString(&xdbuf, yytext);
 		}
 <xd>{xdstop} {
-				yylval.str = xdbuf.data;
+				syncrep_yylval.str = xdbuf.data;
 				xdbuf.data = NULL;
 				BEGIN(INITIAL);
 				return NAME;
 		}
 <xd><<EOF>> {
-				yyerror("unterminated quoted identifier");
+				syncrep_yyerror("unterminated quoted identifier");
 				return JUNK;
 		}
 
 {identifier} {
-				yylval.str = pstrdup(yytext);
+				syncrep_yylval.str = pstrdup(yytext);
 				return NAME;
 		}
 
 {digit}+	{
-				yylval.str = pstrdup(yytext);
+				syncrep_yylval.str = pstrdup(yytext);
 				return NUM;
 		}
 
 "*"		{
-				yylval.str = "*";
+				syncrep_yylval.str = "*";
 				return NAME;
 		}