From 05ef50d08aa8d78e0346d8c60e44a03d1e6ffb40 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Mon, 23 Apr 2018 00:25:31 +0000
Subject: [PATCH] Fix an unreachable branch associated with stack overflow in
 the LEMON-generated parser.

FossilOrigin-Name: e3064ba3b68ca2a1c54561756e8c898866a19ef6e785d315171cd47827a50c85
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 tool/lempar.c | 20 ++++++++++----------
 3 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/manifest b/manifest
index fbd61bf9a3..70324922b1 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Performance\simprovements\son\sthe\smain\sloop\sof\sthe\sLEMON-generated\sparser.
-D 2018-04-21T22:40:08.247
+C Fix\san\sunreachable\sbranch\sassociated\swith\sstack\soverflow\sin\sthe\nLEMON-generated\sparser.
+D 2018-04-23T00:25:31.966
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 5ce9343cba9c189046f1afe6d2bcc1f68079439febc05267b98aec6ecc752439
@@ -1645,7 +1645,7 @@ F tool/genfkey.test 4196a8928b78f51d54ef58e99e99401ab2f0a7e5
 F tool/getlock.c f4c39b651370156cae979501a7b156bdba50e7ce
 F tool/kvtest-speed.sh 4761a9c4b3530907562314d7757995787f7aef8f
 F tool/lemon.c 33892e2a243865f73e6c6e7cecce3c6eb4bb95db4a3d9d86d146c8064feb92fd
-F tool/lempar.c 01f28a4d245f0ea480fab1147c1244fe50434cea924ce258b3e8570a6340a0d3
+F tool/lempar.c bf7db78e7213f1d51516710483eab506fd52bf632c7abfb3e2e9b885c90c03e1
 F tool/libvers.c caafc3b689638a1d88d44bc5f526c2278760d9b9
 F tool/loadfts.c c3c64e4d5e90e8ba41159232c2189dba4be7b862
 F tool/logest.c 11346aa019e2e77a00902aa7d0cabd27bd2e8cca
@@ -1725,7 +1725,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P dcf2bafc159179859b91ffea3a4ebd70b5ca6de9e1d515eaf9afde8cfff26c6c
-R 30c687ea8cbf9562ea971a83f0b60716
+P fec1ebadeb9d6b55b19a1c159c543fd7ae67b3307c4caee4d2541bd783630e23
+R ab0db3a54428a9f0725860ac9691f760
 U drh
-Z 5f81242a2fad2cc1a6991b9a8c5f4a01
+Z 527d3a0e1a395ba78e820e4cf3bc4ff9
diff --git a/manifest.uuid b/manifest.uuid
index febf97a27e..cf70910739 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fec1ebadeb9d6b55b19a1c159c543fd7ae67b3307c4caee4d2541bd783630e23
\ No newline at end of file
+e3064ba3b68ca2a1c54561756e8c898866a19ef6e785d315171cd47827a50c85
\ No newline at end of file
diff --git a/tool/lempar.c b/tool/lempar.c
index d2b700a8cf..885cefe143 100644
--- a/tool/lempar.c
+++ b/tool/lempar.c
@@ -747,13 +747,19 @@ static YYACTIONTYPE yy_reduce(
 #if YYSTACKDEPTH>0 
     if( yypParser->yytos>=yypParser->yystackEnd ){
       yyStackOverflow(yypParser);
-      return YY_ACCEPT_ACTION;
+      /* The call to yyStackOverflow() above pops the stack until it is
+      ** empty, causing the main parser loop to exit.  So the return value
+      ** is never used and does not matter. */
+      return 0;
     }
 #else
     if( yypParser->yytos>=&yypParser->yystack[yypParser->yystksz-1] ){
       if( yyGrowStack(yypParser) ){
         yyStackOverflow(yypParser);
-        return YY_ACCEPT_ACTION;
+        /* The call to yyStackOverflow() above pops the stack until it is
+        ** empty, causing the main parser loop to exit.  So the return value
+        ** is never used and does not matter. */
+        return 0;
       }
       yymsp = yypParser->yytos;
     }
@@ -930,14 +936,8 @@ void Parse(
 #endif
       break;
     }else if( yyact==YY_ACCEPT_ACTION ){
-      /* YY_ACCEPT_ACTION also happens on a stack overflow.  We distingush
-      ** the two cases by observing that on a true accept, there should be
-      ** a single token left on the stack, whereas on a stack overflow,
-      ** the stack has been popped (by yyStackOverflow()) to be empty */
-      if( yypParser->yytos > yypParser->yystack ){
-        yypParser->yytos--;
-        yy_accept(yypParser);
-      }
+      yypParser->yytos--;
+      yy_accept(yypParser);
       return;
     }else{
       assert( yyact == YY_ERROR_ACTION );