When deleting an SQL function that does not exist, return without doing

anything at all rather than creating a tombstone function.  In this way,
function deletes that happen inside virtual-table destructors that are run
when a database connection is closing do not create new tombstones in the
function table after the function table has already been purged.
[forum:/forumpost/726219164b|forum post 726219164b].

FossilOrigin-Name: 391c73132c80df944fb49a17d8fe78203c54ac48f968ee9dd9dd8c769c0b4b10

2 files changed, 10 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 785b646d2..bd92f7661 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1884,6 +1884,10 @@ int sqlite3CreateFunc(
     }else{
       sqlite3ExpirePreparedStatements(db, 0);
     }
+  }else if( xSFunc==0 && xFinal==0 ){
+    /* Trying to delete a function that does not exist.  This is a no-op.
+    ** https://sqlite.org/forum/forumpost/726219164b */
+    return SQLITE_OK;
   }
 
   p = sqlite3FindFunction(db, zFunctionName, nArg, (u8)enc, 1);
diff --git a/src/test8.c b/src/test8.c
index f984c2e5f..7a532346e 100644
--- a/src/test8.c
+++ b/src/test8.c
@@ -389,6 +389,7 @@ static int echoDestructor(sqlite3_vtab *pVtab){
 typedef struct EchoModule EchoModule;
 struct EchoModule {
   Tcl_Interp *interp;
+  sqlite3 *db;
 };
 
 /*
@@ -1352,6 +1353,9 @@ extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
 extern const char *sqlite3ErrName(int);
 
 static void moduleDestroy(void *p){
+  EchoModule *pMod = (EchoModule*)p;
+  sqlite3_create_function(pMod->db, "function_that_does_not_exist_0982ma98",
+                          SQLITE_ANY, 1, 0, 0, 0, 0);
   sqlite3_free(p);
 }
 
@@ -1376,6 +1380,7 @@ static int SQLITE_TCLAPI register_echo_module(
   /* Virtual table module "echo" */
   pMod = sqlite3_malloc(sizeof(EchoModule));
   pMod->interp = interp;
+  pMod->db = db;
   rc = sqlite3_create_module_v2(
       db, "echo", &echoModule, (void*)pMod, moduleDestroy
   );
@@ -1384,6 +1389,7 @@ static int SQLITE_TCLAPI register_echo_module(
   if( rc==SQLITE_OK ){
     pMod = sqlite3_malloc(sizeof(EchoModule));
     pMod->interp = interp;
+    pMod->db = db;
     rc = sqlite3_create_module_v2(db, "echo_v2", 
         &echoModuleV2, (void*)pMod, moduleDestroy
     );