Build backend/parser/scan.l and interfaces/ecpg/preproc/pgc.l standalone.

Now that we know about the %top{} trick, we can revert to building flex
lexers as separate .o files.  This is worth doing for a couple of reasons
besides sheer cleanliness.  We can narrow the scope of the -Wno-error flag
that's forced on scan.c.  Also, since these grammar and lexer files are
so large, splitting them into separate build targets should have some
advantages in build speed, particularly in parallel or ccache'd builds.

We have quite a few other .l files that could be changed likewise, but the
above arguments don't apply to them, so the benefit of fixing them seems
pretty minimal.  Leave the rest for some other day.

3 files changed, 8 insertions, 20 deletions

diff --git a/src/backend/parser/Makefile b/src/backend/parser/Makefile
index 0395bd5934a..9cc8946fa1b 100644
--- a/src/backend/parser/Makefile
+++ b/src/backend/parser/Makefile
@@ -12,7 +12,7 @@ include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -I. -I$(srcdir) $(CPPFLAGS)
 
-OBJS= analyze.o gram.o keywords.o kwlookup.o parser.o \
+OBJS= analyze.o gram.o scan.o keywords.o kwlookup.o parser.o \
       parse_agg.o parse_clause.o parse_coerce.o parse_collate.o parse_cte.o \
       parse_expr.o parse_func.o parse_node.o parse_oper.o parse_param.o \
       parse_relation.o parse_target.o parse_type.o parse_utilcmd.o scansup.o
@@ -20,12 +20,9 @@ OBJS= analyze.o gram.o keywords.o kwlookup.o parser.o \
 include $(top_srcdir)/src/backend/common.mk
 
 
-# scan is compiled as part of gram
-gram.o: scan.c
-
 # Latest flex causes warnings in this file.
 ifeq ($(GCC),yes)
-gram.o: CFLAGS += -Wno-error
+scan.o: CFLAGS += -Wno-error
 endif
 
 
@@ -47,7 +44,7 @@ scan.c: FLEX_NO_BACKUP=yes
 
 
 # Force these dependencies to be known even without dependency info built:
-gram.o keywords.o parser.o: gram.h
+gram.o scan.o keywords.o parser.o: gram.h
 
 
 # gram.c, gram.h, and scan.c are in the distribution tarball, so they
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index b9aeb3171f7..a74fb772e14 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -14908,13 +14908,3 @@ parser_init(base_yy_extra_type *yyext)
 {
 	yyext->parsetree = NIL;		/* in case grammar forgets to set it */
 }
-
-/*
- * Must undefine this stuff before including scan.c, since it has different
- * definitions for these macros.
- */
-#undef yyerror
-#undef yylval
-#undef yylloc
-
-#include "scan.c"
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index 69def847376..d6322766c7d 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -1,4 +1,4 @@
-%{
+%top{
 /*-------------------------------------------------------------------------
  *
  * scan.l
@@ -6,7 +6,7 @@
  *
  * NOTE NOTE NOTE:
  *
- * The rules in this file must be kept in sync with psql's lexer!!!
+ * The rules in this file must be kept in sync with psql's psqlscan.l!
  *
  * The rules are designed so that the scanner never has to backtrack,
  * in the sense that there is always a rule that can match the input
@@ -34,12 +34,13 @@
 #include <ctype.h>
 #include <unistd.h>
 
+#include "parser/gramparse.h"
 #include "parser/parser.h"				/* only needed for GUC variables */
-#include "parser/scanner.h"
 #include "parser/scansup.h"
 #include "mb/pg_wchar.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)