Fixes microsoft#32465.

After this was done, I continued to extend the implementation to handle
TupleLike types but it'ss broken since JS doesn't allow splicing
TupleLike values into array literals so pulled that out, and instead
keeping it for reference below.  (It Includes tests, which are broken
too.)

modified   src/compiler/checker.ts
@@ -22268,6 +22268,21 @@ namespace ts {
                         else hasNonEndingSpreadElement = true;
                     }
                 }
+                else if (spreadType && isTupleLikeType(spreadType)) {
+                    let i = 0, tupleEltType: Type | undefined;
+                    while (tupleEltType = getTypeOfPropertyOfType(spreadType, "" + i as __String)) {
+                        elementTypes.push(tupleEltType);
+                        i++;
+                    }
+                    const stringIndexInfo = getIndexInfoOfType(spreadType, IndexKind.String);
+                    const numberIndexInfo = getIndexInfoOfType(spreadType, IndexKind.Number);
+                    if (stringIndexInfo || numberIndexInfo) {
+                        if (stringIndexInfo) elementTypes.push(stringIndexInfo.type);
+                        if (numberIndexInfo) elementTypes.push(numberIndexInfo.type);
+                        if (i === elementCount - 1) hasEndingSpreadElement = true;
+                        else hasNonEndingSpreadElement = true;
+                    }
+                }
                 else {
                     if (inDestructuringPattern && spreadType) {
                         // Given the following situation:
new file   tests/cases/compiler/spliceTupleLikesWIntegers.ts
@@ -0,0 +1,23 @@
+declare const sb: { [0]: string, [1]: boolean };
+
+let k1: [number, string, boolean];
+k1 = [1, ...sb];
+
+let k2: [number, string, boolean, number];
+k2 = [1, ...sb, 1];
+
+// declare const sb_: [string, ...boolean[]];
+
+// let k3: [number, string, ...boolean[]];
+// k3 = [1, ...sb_];
+
+// declare const sbb_: [string, boolean, ...boolean[]];
+
+// let k4: [number, string, ...boolean[]];
+// k4 = [1, ...sbb_];
+
+// let k5: [number, string, boolean, ...boolean[]];
+// k5 = [1, ...sbb_];
+
+// let k6: [number, string, boolean, boolean, ...boolean[]];
+// k6 = [1, ...sbb_];
new file   tests/cases/compiler/spliceTupleLikesWStrings.ts
@@ -0,0 +1,23 @@
+declare const sb: { 0: string, 1: boolean };
+
+let k1: [number, string, boolean];
+k1 = [1, ...sb];
+
+let k2: [number, string, boolean, number];
+k2 = [1, ...sb, 1];
+
+declare const sb_: { 0: string, [s: string]: (boolean|string) };
+
+let k3: [number, string, ...(boolean|string)[]];
+k3 = [1, ...sb_];
+
+declare const sbb_: { 0: string, 1: boolean, [s: string]: (boolean|string) };
+
+let k4: [number, string, boolean, ...(boolean|string)[]];
+k4 = [1, ...sbb_];
+
+// let k5: [number, string, boolean, ...(boolean|string)[]];
+// k5 = [1, ...sbb_];
+
+// let k6: [number, string, boolean, boolean, ...(boolean|string)[]];
+// k6 = [1, ...sbb_];