diff --git a/manifest b/manifest
index 298d9f0ab3..347a5b8ce1 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Tighter\schecking\sof\saccess\sconstraints\son\sunion\smembers\sin\sSrcItem.\nImproved\sinvariant\schecking.
-D 2024-08-20T19:09:59.313
+C Remove\sunreachable\scode.
+D 2024-08-20T20:01:21.013
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -702,7 +702,7 @@ F src/btmutex.c 79a43670447eacc651519a429f6ece9fd638563cf95b469d6891185ddae2b522
 F src/btree.c 8b42fc7d9efdb2df05c30e8f91ff6cfbd979724ae24bf90269028468b7a13333
 F src/btree.h 55066f513eb095db935169dab1dc2f7c7a747ef223c533f5d4ad4dfed346cbd0
 F src/btreeInt.h 98aadb6dcb77b012cab2574d6a728fad56b337fc946839b9898c4b4c969e30b6
-F src/build.c 69d79a255a6a0547f5e99a1726c3cbd363fa221c4f0458425abc7ba59efb9f83
+F src/build.c c5522b5faf8128227678e194275cefaeb4d063f55dbe70bcff745f1b63a187cf
 F src/callback.c db3a45e376deff6a16c0058163fe0ae2b73a2945f3f408ca32cf74960b28d490
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 64e4b1227b4ed123146f0aa2989131d1fbd9b927b11e80c9d58c6a68f9cd5ce3
@@ -749,18 +749,18 @@ F src/os_win.c 6ff43bac175bd9ed79e7c0f96840b139f2f51d01689a638fd05128becf94908a
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c b08600ebf0db90b6d1e9b8b6577c6fa3877cbe1a100bd0b2899e4c6e9adad4b3
 F src/pager.h 4b1140d691860de0be1347474c51fee07d5420bd7f802d38cbab8ea4ab9f538a
-F src/parse.y 967e0a712de8bee4b2cf82bd9efa36b68afd03cc486d4ea77a945feb49b057dc
+F src/parse.y 5972b7d00af4c8d96fdad781af1ea1d5d51fc3b907ad61bda60e49503274e5ed
 F src/pcache.c 588cc3c5ccaaadde689ed35ce5c5c891a1f7b1f4d1f56f6cf0143b74d8ee6484
 F src/pcache.h 1497ce1b823cf00094bb0cf3bac37b345937e6f910890c626b16512316d3abf5
 F src/pcache1.c 49516ad7718a3626f28f710fa7448ef1fce3c07fd169acbb4817341950264319
 F src/pragma.c 52bfbf6dfd668b69b5eb9bd1186e3a67367c8453807150d6e75239229924f684
 F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c d99931f45416652895e502328ca49fe782cfc4e1ebdcda13b3736d991ebf42ce
-F src/printf.c 17054fb94ffcf7a28362e9a5af4a0f813bd0c52200ae408eeebddc81feed9274
+F src/printf.c 6a87534ebfb9e5346011191b1f3a7ebc457f5938c7e4feeea478ecf53f6a41b2
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c 9afed5fd7b9111633bdb74a73cdc47324e28e4dc6c27113e3e9aee38fb9422ab
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 7addcd53d8f9bef2d47a7e47faeb1f6e401dba02f1f338f532298a24657ea4e6
+F src/select.c 6f1651ca254a6856c2ec5b8a0188bc226e7a454d6741d3f71ebcd631ce147807
 F src/shell.c.in 94571558b0fb28c37a5cf6dbd6ea27285341023a28a8cb5795cd2768fab67704
 F src/sqlite.h.in 1ad9110150773c38ebababbad11b5cb361bcd3997676dec1c91ac5e0416a7b86
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -2205,8 +2205,8 @@ F vsixtest/vsixtest.tcl 6195aba1f12a5e10efc2b8c0009532167be5e301abe5b31385638080
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P bc5f5ce59e1e4323422bda7d002310923f927a03b4fd42749bf04f6c9853956b
-R ee08ce1ecc132f8a5f905e65ae160cc1
+P fd72d3400a8fe5747f494eee81654698acee350bb95b9db269e87d857af03492
+R ed1ab5c9cb5cf9505f2201c6b302f119
 U drh
-Z 01685802d904a82a17f4e5855c564d7e
+Z 40ddef7af9ce2e2b1803942ebd50a97a
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 06a9d2670a..33f57517e4 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fd72d3400a8fe5747f494eee81654698acee350bb95b9db269e87d857af03492
+17699329aa8e234c6793a38db5ca05def9395b287bcc8bc05493b824327edb59
diff --git a/src/build.c b/src/build.c
index b2386035d8..74577ed0d5 100644
--- a/src/build.c
+++ b/src/build.c
@@ -5012,7 +5012,7 @@ int sqlite3SrcItemAttachSubquery(
   int dupSelect      /* If true, attach a copy of pSelect, not pSelect itself.*/
 ){
   Subquery *p;
-  if( pSelect==0 ) return SQLITE_OK;
+  assert( pSelect!=0 );
   assert( pItem->fg.isSubquery==0 );
   if( pItem->fg.fixedSchema ){
     pItem->u4.pSchema = 0;
diff --git a/src/parse.y b/src/parse.y
index a47c587547..926dd6e7d1 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -748,9 +748,8 @@ seltablist(A) ::= stl_prefix(A) nm(Y) dbnm(D) LP exprlist(E) RP as(Z) on_using(N
           pNew->u4.pSubq = pOld->u4.pSubq;
           pOld->u4.pSubq = 0;
           pOld->fg.isSubquery = 0;
-          if( pNew->u4.pSubq->pSelect
-           && (pNew->u4.pSubq->pSelect->selFlags & SF_NestedFrom)!=0
-          ){
+          assert( pNew->u4.pSubq!=0 && pNew->u4.pSubq->pSelect!=0 );
+          if( (pNew->u4.pSubq->pSelect->selFlags & SF_NestedFrom)!=0 ){
             pNew->fg.isNestedFrom = 1;
           }
         }else{
diff --git a/src/printf.c b/src/printf.c
index be7ffc8c76..a140565146 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -858,7 +858,7 @@ void sqlite3_str_vappendf(
           sqlite3_str_appendall(pAccum, pItem->zName);
         }else if( pItem->zAlias ){
           sqlite3_str_appendall(pAccum, pItem->zAlias);
-        }else if( pItem->fg.isSubquery ){/* Because of tag-20240424-1 */
+        }else if( ALWAYS(pItem->fg.isSubquery) ){/* Because of tag-20240424-1 */
           Select *pSel = pItem->u4.pSubq->pSelect;
           assert( pSel!=0 ); 
           if( pSel->selFlags & SF_NestedFrom ){
@@ -870,8 +870,6 @@ void sqlite3_str_vappendf(
           }else{
             sqlite3_str_appendf(pAccum, "(subquery-%u)", pSel->selId);
           }
-        }else{
-          sqlite3_str_appendf(pAccum, "(unknown-data-source-%p)", pItem);
         }
         length = width = 0;
         break;
diff --git a/src/select.c b/src/select.c
index 39955dd60a..655221b067 100644
--- a/src/select.c
+++ b/src/select.c
@@ -4523,10 +4523,7 @@ static int flattenSubquery(
     pSub1 = 0;
   }
   assert( pSubitem->fg.isSubquery==0 );
-  if( pSubitem->fg.fixedSchema==0 ){
-    sqlite3DbFree(db, pSubitem->u4.zDatabase);
-    pSubitem->u4.zDatabase = 0;
-  }
+  assert( pSubitem->fg.fixedSchema==0 );
   sqlite3DbFree(db, pSubitem->zName);
   sqlite3DbFree(db, pSubitem->zAlias);
   pSubitem->zName = 0;
@@ -5601,7 +5598,6 @@ static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){
   /* If we reach this point, that means the transformation is required. */
 
   pParse = pWalker->pParse;
-  if( pParse->nErr ) return WRC_Abort;
   db = pParse->db;
   pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
   if( pNew==0 ) return WRC_Abort;