Improved error messages when an ALTER TABLE RENAME COLUMN fails due to a

duplicate column name.

FossilOrigin-Name: 37d11b8e8224a8b241ff57b9c4b9499db39dde4ddcb56ff8b03a3d08091a4c11

4 files changed, 26 insertions, 11 deletions

diff --git a/src/alter.c b/src/alter.c
index f908933cd..09cbd75bc 100644
--- a/src/alter.c
+++ b/src/alter.c
@@ -1126,7 +1126,6 @@ static void renameColumnFunc(
 
     for(pFKey=sParse.pNewTable->pFKey; pFKey; pFKey=pFKey->pNextFrom){
       for(i=0; i<pFKey->nCol; i++){
-        RenameToken *pTok = 0;
         if( bFKOnly==0 && pFKey->aCol[i].iFrom==sCtx.iCol ){
           renameTokenFind(&sParse, &sCtx, (void*)&pFKey->aCol[i]);
         }
diff --git a/src/prepare.c b/src/prepare.c
index 14017d879..4d4b98d8a 100644
--- a/src/prepare.c
+++ b/src/prepare.c
@@ -25,15 +25,23 @@ static void corruptSchema(
   const char *zExtra   /* Error information */
 ){
   sqlite3 *db = pData->db;
-  if( !db->mallocFailed && (db->flags & SQLITE_WriteSchema)==0 ){
+  if( db->mallocFailed ){
+    pData->rc = SQLITE_NOMEM_BKPT;
+  }else if( pData->pzErrMsg[0]!=0 ){
+    /* A error message has already been generated.  Do not overwrite it */
+  }else if( pData->mInitFlags & INITFLAG_AlterTable ){
+    *pData->pzErrMsg = sqlite3DbStrDup(db, zExtra);
+    pData->rc = SQLITE_ERROR;
+  }else if( db->flags & SQLITE_WriteSchema ){
+    pData->rc = SQLITE_CORRUPT_BKPT;
+  }else{
     char *z;
     if( zObj==0 ) zObj = "?";
     z = sqlite3MPrintf(db, "malformed database schema (%s)", zObj);
     if( zExtra && zExtra[0] ) z = sqlite3MPrintf(db, "%z - %s", z, zExtra);
-    sqlite3DbFree(db, *pData->pzErrMsg);
     *pData->pzErrMsg = z;
+    pData->rc = SQLITE_CORRUPT_BKPT;
   }
-  pData->rc = db->mallocFailed ? SQLITE_NOMEM_BKPT : SQLITE_CORRUPT_BKPT;
 }
 
 /*
@@ -132,7 +140,7 @@ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
 ** auxiliary databases.  Return one of the SQLITE_ error codes to
 ** indicate success or failure.
 */
-int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){
+int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){
   int rc;
   int i;
 #ifndef SQLITE_OMIT_DEPRECATED
@@ -167,6 +175,7 @@ int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){
   initData.iDb = iDb;
   initData.rc = SQLITE_OK;
   initData.pzErrMsg = pzErrMsg;
+  initData.mInitFlags = mFlags;
   sqlite3InitCallback(&initData, 3, (char **)azArg, 0);
   if( initData.rc ){
     rc = initData.rc;
@@ -373,14 +382,14 @@ int sqlite3Init(sqlite3 *db, char **pzErrMsg){
   assert( db->nDb>0 );
   /* Do the main schema first */
   if( !DbHasProperty(db, 0, DB_SchemaLoaded) ){
-    rc = sqlite3InitOne(db, 0, pzErrMsg);
+    rc = sqlite3InitOne(db, 0, pzErrMsg, 0);
     if( rc ) return rc;
   }
   /* All other schemas after the main schema. The "temp" schema must be last */
   for(i=db->nDb-1; i>0; i--){
     assert( i==1 || sqlite3BtreeHoldsMutex(db->aDb[i].pBt) );
     if( !DbHasProperty(db, i, DB_SchemaLoaded) ){
-      rc = sqlite3InitOne(db, i, pzErrMsg);
+      rc = sqlite3InitOne(db, i, pzErrMsg, 0);
       if( rc ) return rc;
     }
   }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 7b01bb27f..e7d86ba3b 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3329,9 +3329,15 @@ typedef struct {
   char **pzErrMsg;    /* Error message stored here */
   int iDb;            /* 0 for main database.  1 for TEMP, 2.. for ATTACHed */
   int rc;             /* Result code stored here */
+  u32 mInitFlags;     /* Flags controlling error messages */
 } InitData;
 
 /*
+** Allowed values for mInitFlags
+*/
+#define INITFLAG_AlterTable   0x0001  /* This is a reparse after ALTER TABLE */
+
+/*
 ** Structure containing global configuration data for the SQLite library.
 **
 ** This structure also contains some state information.
@@ -3801,7 +3807,7 @@ void sqlite3ExprListDelete(sqlite3*, ExprList*);
 u32 sqlite3ExprListFlags(const ExprList*);
 int sqlite3Init(sqlite3*, char**);
 int sqlite3InitCallback(void*, int, char**, char**);
-int sqlite3InitOne(sqlite3*, int, char**);
+int sqlite3InitOne(sqlite3*, int, char**, u32);
 void sqlite3Pragma(Parse*,Token*,Token*,Token*,int);
 #ifndef SQLITE_OMIT_VIRTUALTABLE
 Module *sqlite3PragmaVtabRegister(sqlite3*,const char *zName);
diff --git a/src/vdbe.c b/src/vdbe.c
index 62abaa301..c8ee9860f 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -5722,7 +5722,8 @@ case OP_SqlExec: {
 /* Opcode: ParseSchema P1 * * P4 *
 **
 ** Read and parse all entries from the SQLITE_MASTER table of database P1
-** that match the WHERE clause P4. 
+** that match the WHERE clause P4.  If P4 is a NULL pointer, then the
+** entire schema for P1 is reparsed.
 **
 ** This opcode invokes the parser to create a new virtual machine,
 ** then runs the new virtual machine.  It is thus a re-entrant opcode.
@@ -5751,11 +5752,11 @@ case OP_ParseSchema: {
   if( pOp->p4.z==0 ){
     sqlite3SchemaClear(db->aDb[iDb].pSchema);
     db->mDbFlags &= ~DBFLAG_SchemaKnownOk;
-    rc = sqlite3InitOne(db, iDb, &p->zErrMsg);
+    rc = sqlite3InitOne(db, iDb, &p->zErrMsg, INITFLAG_AlterTable);
     db->mDbFlags |= DBFLAG_SchemaChange;
   }else
 #endif
-  /* Used to be a conditional */ {
+  {
     zMaster = MASTER_NAME;
     initData.db = db;
     initData.iDb = pOp->p1;