Merge pull request #15849 from Microsoft/allow-spread-after-required-params

Allow spreading arrays after required parameters

src/compiler/checker.ts

@@ -14760,7 +14760,7 @@ namespace ts {
             // If spread arguments are present, check that they correspond to a rest parameter. If so, no
             // further checking is necessary.
             if (spreadArgIndex >= 0) {
-                return isRestParameterIndex(signature, spreadArgIndex);
+                return isRestParameterIndex(signature, spreadArgIndex) || spreadArgIndex >= signature.minArgumentCount;
             }
 
             // Too many arguments implies incorrect arity.

tests/baselines/reference/callWithSpread2.errors.txt

@@ -0,0 +1,81 @@
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(30,5): error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+  Type 'string' is not assignable to type 'number'.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(31,5): error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+  Type 'string' is not assignable to type 'number'.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(32,13): error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+  Type 'string' is not assignable to type 'number'.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(33,13): error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+  Type 'string' is not assignable to type 'number'.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(34,11): error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+  Type 'string' is not assignable to type 'number'.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(35,11): error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+  Type 'string' is not assignable to type 'number'.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(36,1): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(37,1): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts(38,1): error TS2346: Supplied parameters do not match any signature of call target.
+
+
+==== tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts (9 errors) ====
+    declare function all(a?: number, b?: number): void;
+    declare function weird(a?: number | string, b?: number | string): void;
+    declare function prefix(s: string, a?: number, b?: number): void;
+    declare function rest(s: string, a?: number, b?: number,  ...rest: number[]): void;
+    declare function normal(s: string): void;
+    declare function thunk(): string;
+    
+    declare var ns: number[];
+    declare var mixed: (number | string)[];
+    declare var tuple: [number, string];
+    
+    // good
+    all(...ns)
+    weird(...ns)
+    weird(...mixed)
+    weird(...tuple)
+    prefix("a", ...ns)
+    rest("d", ...ns)
+    
+    
+    // this covers the arguments case
+    normal("g", ...ns)
+    normal("h", ...mixed)
+    normal("i", ...tuple)
+    thunk(...ns)
+    thunk(...mixed)
+    thunk(...tuple)
+    
+    // bad
+    all(...mixed)
+        ~~~~~~~~
+!!! error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'string' is not assignable to type 'number'.
+    all(...tuple)
+        ~~~~~~~~
+!!! error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'string' is not assignable to type 'number'.
+    prefix("b", ...mixed)
+                ~~~~~~~~
+!!! error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'string' is not assignable to type 'number'.
+    prefix("c", ...tuple)
+                ~~~~~~~~
+!!! error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'string' is not assignable to type 'number'.
+    rest("e", ...mixed)
+              ~~~~~~~~
+!!! error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'string' is not assignable to type 'number'.
+    rest("f", ...tuple)
+              ~~~~~~~~
+!!! error TS2345: Argument of type 'string | number' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'string' is not assignable to type 'number'.
+    prefix(...ns) // required parameters are required
+    ~~~~~~~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    prefix(...mixed)
+    ~~~~~~~~~~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    prefix(...tuple)
+    ~~~~~~~~~~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    

tests/baselines/reference/callWithSpread2.js

@@ -0,0 +1,66 @@
+//// [callWithSpread2.ts]
+declare function all(a?: number, b?: number): void;
+declare function weird(a?: number | string, b?: number | string): void;
+declare function prefix(s: string, a?: number, b?: number): void;
+declare function rest(s: string, a?: number, b?: number,  ...rest: number[]): void;
+declare function normal(s: string): void;
+declare function thunk(): string;
+
+declare var ns: number[];
+declare var mixed: (number | string)[];
+declare var tuple: [number, string];
+
+// good
+all(...ns)
+weird(...ns)
+weird(...mixed)
+weird(...tuple)
+prefix("a", ...ns)
+rest("d", ...ns)
+
+
+// this covers the arguments case
+normal("g", ...ns)
+normal("h", ...mixed)
+normal("i", ...tuple)
+thunk(...ns)
+thunk(...mixed)
+thunk(...tuple)
+
+// bad
+all(...mixed)
+all(...tuple)
+prefix("b", ...mixed)
+prefix("c", ...tuple)
+rest("e", ...mixed)
+rest("f", ...tuple)
+prefix(...ns) // required parameters are required
+prefix(...mixed)
+prefix(...tuple)
+
+
+//// [callWithSpread2.js]
+// good
+all.apply(void 0, ns);
+weird.apply(void 0, ns);
+weird.apply(void 0, mixed);
+weird.apply(void 0, tuple);
+prefix.apply(void 0, ["a"].concat(ns));
+rest.apply(void 0, ["d"].concat(ns));
+// this covers the arguments case
+normal.apply(void 0, ["g"].concat(ns));
+normal.apply(void 0, ["h"].concat(mixed));
+normal.apply(void 0, ["i"].concat(tuple));
+thunk.apply(void 0, ns);
+thunk.apply(void 0, mixed);
+thunk.apply(void 0, tuple);
+// bad
+all.apply(void 0, mixed);
+all.apply(void 0, tuple);
+prefix.apply(void 0, ["b"].concat(mixed));
+prefix.apply(void 0, ["c"].concat(tuple));
+rest.apply(void 0, ["e"].concat(mixed));
+rest.apply(void 0, ["f"].concat(tuple));
+prefix.apply(void 0, ns); // required parameters are required
+prefix.apply(void 0, mixed);
+prefix.apply(void 0, tuple);

tests/cases/conformance/expressions/functionCalls/callWithSpread2.ts

@@ -0,0 +1,38 @@
+declare function all(a?: number, b?: number): void;
+declare function weird(a?: number | string, b?: number | string): void;
+declare function prefix(s: string, a?: number, b?: number): void;
+declare function rest(s: string, a?: number, b?: number,  ...rest: number[]): void;
+declare function normal(s: string): void;
+declare function thunk(): string;
+
+declare var ns: number[];
+declare var mixed: (number | string)[];
+declare var tuple: [number, string];
+
+// good
+all(...ns)
+weird(...ns)
+weird(...mixed)
+weird(...tuple)
+prefix("a", ...ns)
+rest("d", ...ns)
+
+
+// this covers the arguments case
+normal("g", ...ns)
+normal("h", ...mixed)
+normal("i", ...tuple)
+thunk(...ns)
+thunk(...mixed)
+thunk(...tuple)
+
+// bad
+all(...mixed)
+all(...tuple)
+prefix("b", ...mixed)
+prefix("c", ...tuple)
+rest("e", ...mixed)
+rest("f", ...tuple)
+prefix(...ns) // required parameters are required
+prefix(...mixed)
+prefix(...tuple)