From d3ec02d38e704f93edcbc162c614523b9fc6f7f0 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Fri, 12 Jun 2009 02:27:14 +0000
Subject: [PATCH] Modifications to the parser to eliminate unreachable code.
 (CVS 6749)

FossilOrigin-Name: 457e0b245b1833c0d297bc6f4ff9785e6a2cee02
---
 manifest      | 14 +++++++-------
 manifest.uuid |  2 +-
 src/parse.y   | 12 +++++++++---
 tool/lempar.c | 14 ++++++++++++++
 4 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/manifest b/manifest
index 8419bf4776..6bd0ad70f3 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Honor\sthe\sSQLITE_OPEN_READONLY\sflag\seven\son\sa\s:memory:\sor\stemporary\sdatabase,\neven\sthough\ssuch\sa\sdatabase\sis\spointless.\s\sTicket\s#3908.\s(CVS\s6748)
-D 2009-06-11T17:32:45
+C Modifications\sto\sthe\sparser\sto\seliminate\sunreachable\scode.\s(CVS\s6749)
+D 2009-06-12T02:27:15
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 8b8fb7823264331210cddf103831816c286ba446
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -148,7 +148,7 @@ F src/os_unix.c e55d977c516ed880a2f83f0610b019efd9f8bc06
 F src/os_win.c 725c38a524d168ce280446ad8761d731bc516405
 F src/pager.c efdd56a49622fe87d5cf4b6e69aeb62b45bcb9b0
 F src/pager.h 73f481a308a873ccd626d97331c081db3b53e2e5
-F src/parse.y 07690df997d50b3fdb5e5121e5a27f1a080db13d
+F src/parse.y 5d6ab0304cdbe6f156e763adba9b95bac2800a10
 F src/pcache.c 395f752a13574120bd7513a400ba02a265aaa76d
 F src/pcache.h 9b927ccc5a538e31b4c3bc7eec4f976db42a1324
 F src/pcache1.c 97e7e8e6e34026fb43b47d08532b0c02e959c26c
@@ -714,7 +714,7 @@ F tool/fragck.tcl 5265a95126abcf6ab357f7efa544787e5963f439
 F tool/genfkey.README cf68fddd4643bbe3ff8e31b8b6d8b0a1b85e20f4
 F tool/genfkey.test 405a43d54f1646bfaa7a84b03bb959aef62a3a49
 F tool/lemon.c 1a94e70103e59f20df8f81539a453629df2aa523
-F tool/lempar.c aeba88b8566ff66f8a67c96b3eb2dd95e7d8908d
+F tool/lempar.c d2fbe360eb398075947ba6de9197f99247d3d5a8
 F tool/mkkeywordhash.c 511a848b2ac7a3d93f36adc1e1086b4c5741224b
 F tool/mkopts.tcl 66ac10d240cc6e86abd37dc908d50382f84ff46e x
 F tool/mkspeedsql.tcl a1a334d288f7adfe6e996f2e712becf076745c97
@@ -733,7 +733,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P 1fdb3e1e9af0672072f133dde06594fea2ef13c5
-R 823b08d915257a93dc411921f9d74d82
+P 73ba841ac1ed39fb09b3917bafe0ce349e88eb04
+R 75fd71147dd2bc566349956acaaf3bc9
 U drh
-Z ad0e99c3cc9d6218240a0d7748e56426
+Z c4d949dc1090f86c65a60e0c95668a95
diff --git a/manifest.uuid b/manifest.uuid
index 8edfb50ab6..2447cc1304 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-73ba841ac1ed39fb09b3917bafe0ce349e88eb04
\ No newline at end of file
+457e0b245b1833c0d297bc6f4ff9785e6a2cee02
\ No newline at end of file
diff --git a/src/parse.y b/src/parse.y
index d30f89f269..9401e13cd4 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -14,7 +14,7 @@
 ** the parser.  Lemon will also generate a header file containing
 ** numeric codes for all of the tokens.
 **
-** @(#) $Id: parse.y,v 1.278 2009/05/28 01:00:55 drh Exp $
+** @(#) $Id: parse.y,v 1.279 2009/06/12 02:27:15 drh Exp $
 */
 
 // All token codes are small integers with #defines that begin with "TK_"
@@ -53,6 +53,12 @@
 %include {
 #include "sqliteInt.h"
 
+/*
+** Disable all error recovery processing in the parser push-down
+** automaton.
+*/
+#define YYNOERRORRECOVERY 1
+
 /*
 ** An instance of this structure holds information about the
 ** LIMIT clause of a SELECT statement.
@@ -479,7 +485,7 @@ from(A) ::= FROM seltablist(X). {
 //
 stl_prefix(A) ::= seltablist(X) joinop(Y).    {
    A = X;
-   if( A && A->nSrc>0 ) A->a[A->nSrc-1].jointype = (u8)Y;
+   if( ALWAYS(A && A->nSrc>0) ) A->a[A->nSrc-1].jointype = (u8)Y;
 }
 stl_prefix(A) ::= .                           {A = 0;}
 seltablist(A) ::= stl_prefix(X) nm(Y) dbnm(D) as(Z) indexed_opt(I) on_opt(N) using_opt(U). {
@@ -573,7 +579,7 @@ sortlist(A) ::= sortlist(X) COMMA sortitem(Y) sortorder(Z). {
 }
 sortlist(A) ::= sortitem(Y) sortorder(Z). {
   A = sqlite3ExprListAppend(pParse,0,Y);
-  if( A && A->a ) A->a[0].sortOrder = (u8)Z;
+  if( A && ALWAYS(A->a) ) A->a[0].sortOrder = (u8)Z;
 }
 sortitem(A) ::= expr(X).   {A = X.pExpr;}
 
diff --git a/tool/lempar.c b/tool/lempar.c
index 8ca1e3b9eb..4ab90c2479 100644
--- a/tool/lempar.c
+++ b/tool/lempar.c
@@ -608,6 +608,7 @@ static void yy_reduce(
 /*
 ** The following code executes when the parse fails
 */
+#ifndef YYNOERRORRECOVERY
 static void yy_parse_failed(
   yyParser *yypParser           /* The parser */
 ){
@@ -623,6 +624,7 @@ static void yy_parse_failed(
 %%
   ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
 }
+#endif /* YYNOERRORRECOVERY */
 
 /*
 ** The following code executes when a syntax error first occurs.
@@ -790,6 +792,18 @@ void Parse(
       }
       yypParser->yyerrcnt = 3;
       yyerrorhit = 1;
+#elif defined(YYNOERRORRECOVERY)
+      /* If the YYNOERRORRECOVERY macro is defined, then do not attempt to
+      ** do any kind of error recovery.  Instead, simply invoke the syntax
+      ** error routine and continue going as if nothing had happened.
+      **
+      ** Applications can set this macro (for example inside %include) if
+      ** they intend to abandon the parse upon the first syntax error seen.
+      */
+      yy_syntax_error(yypParser,yymajor,yyminorunion);
+      yy_destructor(yypParser,(YYCODETYPE)yymajor,&yyminorunion);
+      yymajor = YYNOCODE;
+      
 #else  /* YYERRORSYMBOL is not defined */
       /* This is what we do if the grammar does not define ERROR:
       **