Add the SQLITE_RESULT_SUBTYPE flag for application-defined functions. Add

the -DSQLITE_STRICT_SUBTYPE=1 compile-time option that raises an error if
any function invokes sqlite3_result_subtype() without the SQLITE_RESULT_SUBTYPE
flag.  SQLITE_RESULT_SUBTYPE prevents an indexed value of that function from
being used to replace an equivalent expression, since the indexed expression
does not carry the subtype.

FossilOrigin-Name: 65a9cfc466d3d904af50fa5eba46d29c5a24e7dde06e5c50c03b343723be7441

10 files changed, 153 insertions, 66 deletions

diff --git a/manifest b/manifest
index 2fb4ef463..9925ad5ea 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C JSON5\sbug\sfix:\s\sEscape\sdouble-quotes\sthat\soccur\sinside\sof\ssingle-quoted\sstrings.
-D 2023-11-09T01:56:55.242
+C Add\sthe\sSQLITE_RESULT_SUBTYPE\sflag\sfor\sapplication-defined\sfunctions.\s\sAdd\nthe\s-DSQLITE_STRICT_SUBTYPE=1\scompile-time\soption\sthat\sraises\san\serror\sif\nany\sfunction\sinvokes\ssqlite3_result_subtype()\swithout\sthe\sSQLITE_RESULT_SUBTYPE\nflag.\s\sSQLITE_RESULT_SUBTYPE\sprevents\san\sindexed\svalue\sof\sthat\sfunction\sfrom\nbeing\sused\sto\sreplace\san\sequivalent\sexpression,\ssince\sthe\sindexed\sexpression\ndoes\snot\scarry\sthe\ssubtype.
+D 2023-11-09T17:42:46.938
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -681,10 +681,10 @@ F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
 F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
-F src/json.c 955a46d0ac0d4958fb84c2ed1c2e1eafde262a00edc7a31e7e04aecf137778c7
+F src/json.c b2045aafc52f0475dc5d723d11cc0aaa9e1d233a28031b08c8174a3e407ed50c
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 7432c944ff197046d67a1207790a1b13eec4548c85a9457eb0896bb3641dfb36
-F src/main.c e1bc8864834697503d370d94613be945d05ca1c5ebdda43e7d5c8ee8c48d433c
+F src/main.c 1b89f3de98d1b59fec5bac1d66d6ece21f703821b8eaa0d53d9604c35309f6f9
 F src/malloc.c f016922435dc7d1f1f5083a03338a3e91f8c67ce2c5bdcfa4cdef62e612f5fcc
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 3bb59158c38e05f6270e761a9f435bf19827a264c13d1631c58b84bdc96d73b2
@@ -723,10 +723,10 @@ F src/resolve.c 31229276a8eb5b5de1428cd2d80f6f1cf8ffc5248be25e47cf575df12f1b8f23
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
 F src/select.c a19daa26e95f7245106a31f288b2f50c72d1f2cc156703f04c8c91450e111515
 F src/shell.c.in aebfbedaa7706d2c73ab7366a19fc8bc40ea68b70d2529f7feef54e6eb077ea2
-F src/sqlite.h.in a0fce680a40fe81b13eae3749d001134d9fe0a43aecc09a8986520d5119acfcd
+F src/sqlite.h.in 4f841d3d117b830ee5ee45e8d89ceff1195f3ebb72d041ace8d116ba4c103b35
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 3f046c04ea3595d6bfda99b781926b17e672fd6d27da2ba6d8d8fc39981dcb54
-F src/sqliteInt.h fde93552e5bfc8ed59d689c6ff3b982f05b9944eff57067bdc21adf39a79037c
+F src/sqliteInt.h 08efc0ad9ddbbc5ea859111521dff2c4cecc589c0c9a3e4840c927663b31445b
 F src/sqliteLimit.h 33b1c9baba578d34efe7dfdb43193b366111cdf41476b1e82699e14c11ee1fb6
 F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -794,7 +794,7 @@ F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
 F src/vdbe.c 14479441337135eed8e290fb1d4abb7db657d93217a3b1ea8a2f031d3895536a
 F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
 F src/vdbeInt.h 949669dfd8a41550d27dcb905b494f2ccde9a2e6c1b0b04daa1227e2e74c2b2c
-F src/vdbeapi.c fe654b1f54e1feebcaed6c2ae3ed035cc65bfeb9a1169bed866abc42bfc63ff6
+F src/vdbeapi.c dd812ddd2f7806519e9d492c820456f86628bb6014b559034506e7f9d7f683c5
 F src/vdbeaux.c dffcf79e7e415fcd6e4c8ac1ec7124cae5257018443adf09551c807655b04993
 F src/vdbeblob.c 13f9287b55b6356b4b1845410382d6bede203ceb29ef69388a4a3d007ffacbe5
 F src/vdbemem.c 0012d5f01cc866833847c2f3ae4c318ac53a1cb3d28acad9c35e688039464cf0
@@ -806,11 +806,11 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 01e051a1e713d9eabdb25df38602837cec8f4c2cae448ce2cf6accc87af903e9
 F src/wal.h ba252daaa94f889f4b2c17c027e823d9be47ce39da1d3799886bbd51f0490452
 F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
-F src/where.c 313ce81270d2a414672370e1ee74e65949ad620519193d4cac2986d073cbc8a0
+F src/where.c d6ac0f598e725412af5b4484fe98187a129f3c8778c7dbc18ac7477294e190ca
 F src/whereInt.h 4b38c5889514e3aead3f27d0ee9a26e47c3f150efc59e2a8b4e3bc8835e4d7a1
 F src/wherecode.c 5d77db30a2a3dd532492ae882de114edba2fae672622056b1c7fd61f5917a8f1
 F src/whereexpr.c dc5096eca5ed503999be3bdee8a90c51361289a678d396a220912e9cb73b3c00
-F src/window.c ad21e2b73ec75acc79dde2576c573f54a338b0c49e9de847ce984f9b9595b5e2
+F src/window.c 5b1387d59df30d481ed14cceef5f4d1dab1f8752aa106ba72c8b62777bd139d2
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test ce1aafc86e110685b324e9a763eab4f2a73f737842ec3b687bd965867de90627
 F test/affinity3.test f094773025eddf31135c7ad4cde722b7696f8eb07b97511f98585addf2a510a9
@@ -1266,7 +1266,7 @@ F test/index8.test caa097735c91dbc23d8a402f5e63a2a03c83840ba3928733ed7f9a03f8a91
 F test/index9.test 2ac891806a4136ef3e91280477e23114e67575207dc331e6797fa0ed9379f997
 F test/indexA.test 11d84f6995e6e5b9d8315953fb1b6d29772ee7c7803ee9112715e7e4dd3e4974
 F test/indexedby.test f21eca4f7a6ffe14c8500a7ad6cd53166666c99e5ccd311842a28bc94a195fe0
-F test/indexexpr1.test 62558b1cfd7ccbe7bc015849cc6d1a13ef124e80cbd5b3a98dc66c3c9cce0cf4
+F test/indexexpr1.test 833f511213a5e26549186813f0566bd72f978177a7e6e98a2d2dd695de3c670d
 F test/indexexpr2.test 1c382e81ef996d8ae8b834a74f2a9013dddf59214c32201d7c8a656d739f999a
 F test/indexfault.test 98d78a8ff1f5335628b62f886a1cb7c7dac1ef6d48fa39c51ec871c87dce9811
 F test/init.test 15c823093fdabbf7b531fe22cf037134d09587a7
@@ -2139,9 +2139,9 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 36259009c5b581ea692e8c86f505783336e4615bb5134e3afd5498f10eb36239
-Q +1c98d46d60ef1494bd8b7561c7d0cd5aafc178201a6f1f0da25dea6140b91cd0
-R 1e3ac99732ab4ea8b7a813491da4d5ab
+P 6cc57bb2ce92f64af59c569696d4fbd08183feffaeee560450d13370d60f96d5
+Q +ba789a7804ab96d81b15d6ef6fed1f802fa69db47cf91d368933e55289fa1d6e
+R 69f002c2820c1b9e462a76de68ba462a
 U drh
-Z 1d80f11149e195a71e53f694d5b1d56f
+Z bed442c06ca9c36150f2f0b4e625ecbc
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 27ccaef05..bbff5fbc9 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-6cc57bb2ce92f64af59c569696d4fbd08183feffaeee560450d13370d60f96d5
\ No newline at end of file
+65a9cfc466d3d904af50fa5eba46d29c5a24e7dde06e5c50c03b343723be7441
\ No newline at end of file
diff --git a/src/json.c b/src/json.c
index f1ad0900d..de7143bb1 100644
--- a/src/json.c
+++ b/src/json.c
@@ -839,7 +839,8 @@ static void jsonReturnJson(
   JsonParse *pParse,          /* The complete JSON */
   JsonNode *pNode,            /* Node to return */
   sqlite3_context *pCtx,      /* Return value for this function */
-  int bGenerateAlt            /* Also store the rendered text in zAlt */
+  int bGenerateAlt,           /* Also store the rendered text in zAlt */
+  int omitSubtype             /* Do not call sqlite3_result_subtype() */
 ){
   JsonString s;
   if( pParse->oom ){
@@ -854,7 +855,7 @@ static void jsonReturnJson(
       pParse->nAlt = s.nUsed;
     }
     jsonResult(&s);
-    sqlite3_result_subtype(pCtx, JSON_SUBTYPE);
+    if( !omitSubtype ) sqlite3_result_subtype(pCtx, JSON_SUBTYPE);
   }
 }
 
@@ -895,7 +896,8 @@ static u32 jsonHexToInt4(const char *z){
 static void jsonReturn(
   JsonParse *pParse,          /* Complete JSON parse tree */
   JsonNode *pNode,            /* Node to return */
-  sqlite3_context *pCtx       /* Return value for this function */
+  sqlite3_context *pCtx,      /* Return value for this function */
+  int omitSubtype             /* Do not call sqlite3_result_subtype() */
 ){
   switch( pNode->eType ){
     default: {
@@ -1041,7 +1043,7 @@ static void jsonReturn(
     }
     case JSON_ARRAY:
     case JSON_OBJECT: {
-      jsonReturnJson(pParse, pNode, pCtx, 0);
+      jsonReturnJson(pParse, pNode, pCtx, 0, omitSubtype);
       break;
     }
   }
@@ -2393,7 +2395,7 @@ static void jsonParseFunc(
   printf("iSubst    = %u\n", p->iSubst);
   printf("iHold     = %u\n", p->iHold);
   jsonDebugPrintNodeEntries(p->aNode, p->nNode);
-  jsonReturnJson(p, p->aNode, ctx, 1);
+  jsonReturnJson(p, p->aNode, ctx, 1, 0);
 }
 
 /*
@@ -2579,15 +2581,14 @@ static void jsonExtractFunc(
       }
       if( pNode ){
         if( flags & JSON_JSON ){
-          jsonReturnJson(p, pNode, ctx, 0);
+          jsonReturnJson(p, pNode, ctx, 0, 0);
         }else{
-          jsonReturn(p, pNode, ctx);
-          sqlite3_result_subtype(ctx, 0);
+          jsonReturn(p, pNode, ctx, 1);
         }
       }
     }else{
       pNode = jsonLookup(p, zPath, 0, ctx);
-      if( p->nErr==0 && pNode ) jsonReturn(p, pNode, ctx);
+      if( p->nErr==0 && pNode ) jsonReturn(p, pNode, ctx, 0);
     }
   }else{
     /* Two or more PATH arguments results in a JSON array with each
@@ -2713,7 +2714,7 @@ static void jsonPatchFunc(
   if( pResult && pX->oom==0 ){
     jsonDebugPrintParse(pX);
     jsonDebugPrintNode(pResult);
-    jsonReturnJson(pX, pResult, ctx, 0);
+    jsonReturnJson(pX, pResult, ctx, 0, 0);
   }else{
     sqlite3_result_error_nomem(ctx);
   }
@@ -2792,7 +2793,7 @@ static void jsonRemoveFunc(
     }
   }
   if( (pParse->aNode[0].jnFlags & JNODE_REMOVE)==0 ){
-    jsonReturnJson(pParse, pParse->aNode, ctx, 1);
+    jsonReturnJson(pParse, pParse->aNode, ctx, 1, 0);
   }
 remove_done:
   jsonDebugPrintParse(p);
@@ -2921,7 +2922,7 @@ static void jsonReplaceFunc(
       jsonReplaceNode(ctx, pParse, (u32)(pNode - pParse->aNode), argv[i+1]);
     }
   }
-  jsonReturnJson(pParse, pParse->aNode, ctx, 1);
+  jsonReturnJson(pParse, pParse->aNode, ctx, 1, 0);
 replace_err:
   jsonDebugPrintParse(pParse);
   jsonParseFree(pParse);
@@ -2975,7 +2976,7 @@ static void jsonSetFunc(
     }
   }
   jsonDebugPrintParse(pParse);
-  jsonReturnJson(pParse, pParse->aNode, ctx, 1);
+  jsonReturnJson(pParse, pParse->aNode, ctx, 1, 0);
 jsonSetDone:
   jsonParseFree(pParse);
 }
@@ -3490,7 +3491,7 @@ static int jsonEachColumn(
     case JEACH_KEY: {
       if( p->i==0 ) break;
       if( p->eType==JSON_OBJECT ){
-        jsonReturn(&p->sParse, pThis, ctx);
+        jsonReturn(&p->sParse, pThis, ctx, 0);
       }else if( p->eType==JSON_ARRAY ){
         u32 iKey;
         if( p->bRecursive ){
@@ -3506,7 +3507,7 @@ static int jsonEachColumn(
     }
     case JEACH_VALUE: {
       if( pThis->jnFlags & JNODE_LABEL ) pThis++;
-      jsonReturn(&p->sParse, pThis, ctx);
+      jsonReturn(&p->sParse, pThis, ctx, 0);
       break;
     }
     case JEACH_TYPE: {
@@ -3517,7 +3518,7 @@ static int jsonEachColumn(
     case JEACH_ATOM: {
       if( pThis->jnFlags & JNODE_LABEL ) pThis++;
       if( pThis->eType>=JSON_ARRAY ) break;
-      jsonReturn(&p->sParse, pThis, ctx);
+      jsonReturn(&p->sParse, pThis, ctx, 0);
       break;
     }
     case JEACH_ID: {
@@ -3810,34 +3811,43 @@ static sqlite3_module jsonTreeModule = {
 void sqlite3RegisterJsonFunctions(void){
 #ifndef SQLITE_OMIT_JSON
   static FuncDef aJsonFunc[] = {
-    JFUNCTION(json,               1, 0,  jsonRemoveFunc),
-    JFUNCTION(json_array,        -1, 0,  jsonArrayFunc),
-    JFUNCTION(json_array_length,  1, 0,  jsonArrayLengthFunc),
-    JFUNCTION(json_array_length,  2, 0,  jsonArrayLengthFunc),
-    JFUNCTION(json_error_position,1, 0,  jsonErrorFunc),
-    JFUNCTION(json_extract,      -1, 0,  jsonExtractFunc),
-    JFUNCTION(->,                 2, JSON_JSON, jsonExtractFunc),
-    JFUNCTION(->>,                2, JSON_SQL, jsonExtractFunc),
-    JFUNCTION(json_insert,       -1, 0,  jsonSetFunc),
-    JFUNCTION(json_object,       -1, 0,  jsonObjectFunc),
-    JFUNCTION(json_patch,         2, 0,  jsonPatchFunc),
-    JFUNCTION(json_quote,         1, 0,  jsonQuoteFunc),
-    JFUNCTION(json_remove,       -1, 0,  jsonRemoveFunc),
-    JFUNCTION(json_replace,      -1, 0,  jsonReplaceFunc),
-    JFUNCTION(json_set,          -1, JSON_ISSET,  jsonSetFunc),
-    JFUNCTION(json_type,          1, 0,  jsonTypeFunc),
-    JFUNCTION(json_type,          2, 0,  jsonTypeFunc),
-    JFUNCTION(json_valid,         1, 0,  jsonValidFunc),
-#if SQLITE_DEBUG
-    JFUNCTION(json_parse,         1, 0,  jsonParseFunc),
-    JFUNCTION(json_test1,         1, 0,  jsonTest1Func),
+    /*                     calls sqlite3_result_subtype()                    */
+    /*                                  |                                    */
+    /*              Uses cache ______   |   __ calls sqlite3_value_subtype() */
+    /*                               |  |  |                                 */
+    /*          Num args _________   |  |  |   ___ Flags                     */
+    /*                            |  |  |  |  |                              */
+    /*                            |  |  |  |  |                              */
+    JFUNCTION(json,               1, 1, 1, 0, 0,          jsonRemoveFunc),
+    JFUNCTION(json_array,        -1, 0, 1, 1, 0,          jsonArrayFunc),
+    JFUNCTION(json_array_length,  1, 1, 0, 0, 0,          jsonArrayLengthFunc),
+    JFUNCTION(json_array_length,  2, 1, 0, 0, 0,          jsonArrayLengthFunc),
+    JFUNCTION(json_error_position,1, 1, 0, 0, 0,          jsonErrorFunc),
+    JFUNCTION(json_extract,      -1, 1, 1, 0, 0,          jsonExtractFunc),
+    JFUNCTION(->,                 2, 1, 1, 0, JSON_JSON,  jsonExtractFunc),
+    JFUNCTION(->>,                2, 1, 0, 0, JSON_SQL,   jsonExtractFunc),
+    JFUNCTION(json_insert,       -1, 1, 1, 1, 0,          jsonSetFunc),
+    JFUNCTION(json_object,       -1, 0, 1, 1, 0,          jsonObjectFunc),
+    JFUNCTION(json_patch,         2, 1, 1, 0, 0,          jsonPatchFunc),
+    JFUNCTION(json_quote,         1, 0, 1, 1, 0,          jsonQuoteFunc),
+    JFUNCTION(json_remove,       -1, 1, 1, 0, 0,          jsonRemoveFunc),
+    JFUNCTION(json_replace,      -1, 1, 1, 1, 0,          jsonReplaceFunc),
+    JFUNCTION(json_set,          -1, 1, 1, 1, JSON_ISSET, jsonSetFunc),
+    JFUNCTION(json_type,          1, 1, 0, 0, 0,          jsonTypeFunc),
+    JFUNCTION(json_type,          2, 1, 0, 0, 0,          jsonTypeFunc),
+    JFUNCTION(json_valid,         1, 1, 0, 0, 0,          jsonValidFunc),
+#ifdef SQLITE_DEBUG
+    JFUNCTION(json_parse,         1, 1, 1, 0, 0,          jsonParseFunc),
+    JFUNCTION(json_test1,         1, 1, 0, 1, 0,          jsonTest1Func),
 #endif
     WAGGREGATE(json_group_array,  1, 0, 0,
        jsonArrayStep, jsonArrayFinal, jsonArrayValue, jsonGroupInverse,
-       SQLITE_SUBTYPE|SQLITE_UTF8|SQLITE_DETERMINISTIC),
+       SQLITE_SUBTYPE|SQLITE_RESULT_SUBTYPE|SQLITE_UTF8|
+       SQLITE_DETERMINISTIC),
     WAGGREGATE(json_group_object, 2, 0, 0,
        jsonObjectStep, jsonObjectFinal, jsonObjectValue, jsonGroupInverse,
-       SQLITE_SUBTYPE|SQLITE_UTF8|SQLITE_DETERMINISTIC)
+       SQLITE_SUBTYPE|SQLITE_RESULT_SUBTYPE|SQLITE_UTF8|
+       SQLITE_DETERMINISTIC)
   };
   sqlite3InsertBuiltinFuncs(aJsonFunc, ArraySize(aJsonFunc));
 #endif
diff --git a/src/main.c b/src/main.c
index fbe00f5fa..6acfdc325 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1914,7 +1914,7 @@ int sqlite3CreateFunc(
   assert( SQLITE_FUNC_CONSTANT==SQLITE_DETERMINISTIC );
   assert( SQLITE_FUNC_DIRECT==SQLITE_DIRECTONLY );
   extraFlags = enc &  (SQLITE_DETERMINISTIC|SQLITE_DIRECTONLY|
-                       SQLITE_SUBTYPE|SQLITE_INNOCUOUS);
+                       SQLITE_SUBTYPE|SQLITE_INNOCUOUS|SQLITE_RESULT_SUBTYPE);
   enc &= (SQLITE_FUNC_ENCMASK|SQLITE_ANY);
 
   /* The SQLITE_INNOCUOUS flag is the same bit as SQLITE_FUNC_UNSAFE.  But
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 2317d98f7..53c037c3b 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -5573,13 +5573,27 @@ int sqlite3_create_window_function(
 ** </dd>
 **
 ** [[SQLITE_SUBTYPE]] <dt>SQLITE_SUBTYPE</dt><dd>
-** The SQLITE_SUBTYPE flag indicates to SQLite that a function may call
+** The SQLITE_SUBTYPE flag indicates to SQLite that a function might call
 ** [sqlite3_value_subtype()] to inspect the sub-types of its arguments.
-** Specifying this flag makes no difference for scalar or aggregate user
-** functions. However, if it is not specified for a user-defined window
-** function, then any sub-types belonging to arguments passed to the window
-** function may be discarded before the window function is called (i.e.
-** sqlite3_value_subtype() will always return 0).
+** This flag instructs SQLite to omit some corner-case optimizations that
+** might disrupt the operation of the [sqlite3_value_subtype()] function,
+** causing it to return zero rather than the correct subtype().
+** SQL functions that invokes [sqlite3_value_subtype()] should have this
+** property.  If the SQLITE_SUBTYPE property is omitted, then the return
+** value from [sqlite3_value_subtype()] might sometimes be zero even though
+** a non-zero subtype was specified by the function argument expression.
+**
+** [[SQLITE_RESULT_SUBTYPE]] <dt>SQLITE_RESULT_SUBTYPE</dt><dd>
+** The SQLITE_RESULT_SUBTYPE flag indicates to SQLite that a function might call
+** [sqlite3_result_subtype()] to cause a sub-type to be associated with its
+** result.
+** Every function that invokes [sqlite3_result_subtype()] should have this
+** property.  If it does not, then the call to [sqlite3_result_subtype()]
+** might become a no-op if the function is used as term in an
+** [expression index].  On the other hand, SQL functions that never invoke
+** [sqlite3_result_subtype()] should avoid setting this property, as the
+** purpose of this property is to disable certain optimizations that are
+** incompatible with subtypes.
 ** </dd>
 ** </dl>
 */
@@ -5587,6 +5601,7 @@ int sqlite3_create_window_function(
 #define SQLITE_DIRECTONLY       0x000080000
 #define SQLITE_SUBTYPE          0x000100000
 #define SQLITE_INNOCUOUS        0x000200000
+#define SQLITE_RESULT_SUBTYPE   0x001000000
 
 /*
 ** CAPI3REF: Deprecated Functions
@@ -5783,6 +5798,12 @@ int sqlite3_value_encoding(sqlite3_value*);
 ** information can be used to pass a limited amount of context from
 ** one SQL function to another.  Use the [sqlite3_result_subtype()]
 ** routine to set the subtype for the return value of an SQL function.
+**
+** Every [application-defined SQL function] that invoke this interface
+** should include the [SQLITE_SUBTYPE] property in the text
+** encoding argument when the function is [sqlite3_create_function|registered].
+** If the [SQLITE_SUBTYPE] property is omitted, then sqlite3_value_subtype()
+** might return zero instead of the upstream subtype in some corner cases.
 */
 unsigned int sqlite3_value_subtype(sqlite3_value*);
 
@@ -6202,6 +6223,20 @@ int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
 ** higher order bits are discarded.
 ** The number of subtype bytes preserved by SQLite might increase
 ** in future releases of SQLite.
+**
+** Every [application-defined SQL function] that invokes this interface
+** should include the [SQLITE_RESULT_SUBTYPE] property in its
+** text encoding argument when the SQL function is
+** [sqlite3_create_function|registered].  If the [SQLITE_RESULT_SUBTYPE]
+** property is omitted from the function that invokes sqlite3_result_subtype(),
+** then in some cases the sqlite3_result_subtype() might fail to set
+** the result subtype.
+**
+** If SQLite is compiled with -DSQLITE_STRICT_SUBTYPE=1, then any
+** SQL function that invokes the sqlite3_result_subtype() interface
+** and that does not have the SQLITE_RESULT_SUBTYPE property will raise
+** an error.  Future versions of SQLite might enable -DSQLITE_STRICT_SUBTYPE=1
+** by default.
 */
 void sqlite3_result_subtype(sqlite3_context*,unsigned int);
 
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 079f5bd77..6d88c7ab4 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2018,10 +2018,11 @@ struct FuncDestructor {
 #define SQLITE_FUNC_WINDOW   0x00010000 /* Built-in window-only function */
 #define SQLITE_FUNC_INTERNAL 0x00040000 /* For use by NestedParse() only */
 #define SQLITE_FUNC_DIRECT   0x00080000 /* Not for use in TRIGGERs or VIEWs */
-#define SQLITE_FUNC_SUBTYPE  0x00100000 /* Result likely to have sub-type */
+/* SQLITE_SUBTYPE            0x00100000 // Consumer of subtypes */
 #define SQLITE_FUNC_UNSAFE   0x00200000 /* Function has side effects */
 #define SQLITE_FUNC_INLINE   0x00400000 /* Functions implemented in-line */
 #define SQLITE_FUNC_BUILTIN  0x00800000 /* This is a built-in function */
+/*  SQLITE_RESULT_SUBTYPE    0x01000000 // Generator of subtypes */
 #define SQLITE_FUNC_ANYORDER 0x08000000 /* count/min/max aggregate */
 
 /* Identifier numbers for each in-line function */
@@ -2113,9 +2114,10 @@ struct FuncDestructor {
 #define MFUNCTION(zName, nArg, xPtr, xFunc) \
   {nArg, SQLITE_FUNC_BUILTIN|SQLITE_FUNC_CONSTANT|SQLITE_UTF8, \
    xPtr, 0, xFunc, 0, 0, 0, #zName, {0} }
-#define JFUNCTION(zName, nArg, iArg, xFunc) \
-  {nArg, SQLITE_FUNC_BUILTIN|SQLITE_DETERMINISTIC|\
-   SQLITE_FUNC_CONSTANT|SQLITE_UTF8|SQLITE_FUNC_RUNONLY, \
+#define JFUNCTION(zName, nArg, bUseCache, bWS, bRS, iArg, xFunc) \
+  {nArg, SQLITE_FUNC_BUILTIN|SQLITE_DETERMINISTIC|SQLITE_FUNC_CONSTANT|\
+   SQLITE_UTF8|((bUseCache)*SQLITE_FUNC_RUNONLY)|\
+   ((bRS)*SQLITE_SUBTYPE)|((bWS)*SQLITE_RESULT_SUBTYPE), \
    SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, 0, #zName, {0} }
 #define INLINE_FUNC(zName, nArg, iArg, mFlags) \
   {nArg, SQLITE_FUNC_BUILTIN|\
diff --git a/src/vdbeapi.c b/src/vdbeapi.c
index 31ebbc697..3d4b9f76d 100644
--- a/src/vdbeapi.c
+++ b/src/vdbeapi.c
@@ -531,6 +531,18 @@ void sqlite3_result_subtype(sqlite3_context *pCtx, unsigned int eSubtype){
 #ifdef SQLITE_ENABLE_API_ARMOR
   if( pCtx==0 ) return;
 #endif
+#if defined(SQLITE_STRICT_SUBTYPE) && SQLITE_STRICT_SUBTYPE+0!=0
+  if( pCtx->pFunc!=0
+   && (pCtx->pFunc->funcFlags & SQLITE_RESULT_SUBTYPE)==0
+  ){
+    char zErr[200];
+    sqlite3_snprintf(sizeof(zErr), zErr,
+                     "misuse of sqlite3_result_subtype() by %s()", 
+                     pCtx->pFunc->zName);
+    sqlite3_result_error(pCtx, zErr, -1);
+    return;
+  }
+#endif /* SQLITE_STRICT_SUBTYPE */
   pOut = pCtx->pOut;
   assert( sqlite3_mutex_held(pOut->db->mutex) );
   pOut->eSubtype = eSubtype & 0xff;
diff --git a/src/where.c b/src/where.c
index 05ae24f7b..555bd6a34 100644
--- a/src/where.c
+++ b/src/where.c
@@ -5810,6 +5810,20 @@ static SQLITE_NOINLINE void whereAddIndexedExpr(
       continue;
     }
     if( sqlite3ExprIsConstant(pExpr) ) continue;
+    if( pExpr->op==TK_FUNCTION ){
+      /* Functions that might set a subtype should not be replaced by the
+      ** value taken from an expression index since the index omits the
+      ** subtype.  https://sqlite.org/forum/forumpost/68d284c86b082c3e */
+      int n;
+      FuncDef *pDef;
+      sqlite3 *db = pParse->db;
+      assert( ExprUseXList(pExpr) );
+      n = ALWAYS(pExpr->x.pList) ? pExpr->x.pList->nExpr : 0;
+      pDef = sqlite3FindFunction(db, pExpr->u.zToken, n, ENC(db), 0);
+      if( NEVER(pDef==0) || (pDef->funcFlags & SQLITE_RESULT_SUBTYPE)!=0 ){
+        continue;
+      }
+    }
     p = sqlite3DbMallocRaw(pParse->db,  sizeof(IndexedExpr));
     if( p==0 ) break;
     p->pIENext = pParse->pIdxEpr;
diff --git a/src/window.c b/src/window.c
index 2c449592d..62df349fb 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1038,7 +1038,7 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
       assert( ExprUseXList(pWin->pOwner) );
       assert( pWin->pWFunc!=0 );
       pArgs = pWin->pOwner->x.pList;
-      if( pWin->pWFunc->funcFlags & SQLITE_FUNC_SUBTYPE ){
+      if( pWin->pWFunc->funcFlags & SQLITE_SUBTYPE ){
         selectWindowRewriteEList(pParse, pMWin, pSrc, pArgs, pTab, &pSublist);
         pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
         pWin->bExprArgs = 1;
diff --git a/test/indexexpr1.test b/test/indexexpr1.test
index 51ef73bbf..0316ee9d4 100644
--- a/test/indexexpr1.test
+++ b/test/indexexpr1.test
@@ -616,4 +616,18 @@ do_execsql_test indexexpr1-2200 {
          ) v ON v.type = 0 AND v.tag = u.tag;
 } {7 100 8 101}
 
+# 2023-11-08 Forum post https://sqlite.org/forum/forumpost/68d284c86b082c3e
+#
+# Functions that return subtypes and that are indexed cannot be used to
+# cover function calls from the main table, since the indexed value does
+# not know the subtype.
+#
+reset_db
+do_execsql_test indexexpr1-2300 {
+  CREATE TABLE t1(x INT, y TEXT);
+  INSERT INTO t1(x,y) VALUES(1,'{b:5}');
+  CREATE INDEX t1j ON t1(json(y));
+  SELECT json_insert('{}', '$.a', json(y)) FROM t1;
+} {{{"a":{"b":5}}}}
+
 finish_test