Fix __spreadArray for non-concat-spreadables (#45386)

Author: rbuckton

src/compiler/factory/emitHelpers.ts

@@ -647,7 +647,7 @@ namespace ts {
                         ar[i] = from[i];
                     }
                 }
-                return to.concat(ar || from);
+                return to.concat(ar || Array.prototype.slice.call(from));
             };`
     };
 

tests/baselines/reference/argumentExpressionContextualTyping.js

@@ -26,7 +26,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 // In a typed function call, argument expressions are contextually typed by their corresponding parameter types.
 function foo(_a) {

tests/baselines/reference/arrayLiteralExpressionContextualTyping.js

@@ -23,7 +23,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 // In a contextually typed array literal expression containing no spread elements, an element expression at index N is contextually typed by
 //      the type of the property with the numeric name N in the contextual type, if any, or otherwise

tests/baselines/reference/arrayLiteralSpread.js

@@ -31,7 +31,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 function f0() {
     var a = [1, 2, 3];

tests/baselines/reference/arrayLiteralSpreadES5iterable.js

@@ -47,7 +47,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 function f0() {
     var a = [1, 2, 3];

tests/baselines/reference/arrayLiterals2ES5.js

@@ -69,7 +69,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 // SpreadElement:
 //      ...   AssignmentExpression

tests/baselines/reference/arrayLiterals3.js

@@ -47,7 +47,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 // The resulting type an array literal expression is determined as follows:
 //     - If the array literal contains no spread elements and is contextually typed by a tuple-like type,

tests/baselines/reference/callChain.js

@@ -50,7 +50,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 var _a, _b, _c, _d, _e, _f, _g, _h, _j, _k, _l, _m, _o;
 o1 === null || o1 === void 0 ? void 0 : o1();

tests/baselines/reference/callOverload.js

@@ -19,7 +19,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 var n;
 fn(1); // no error

tests/baselines/reference/callWithSpread.js

@@ -81,7 +81,7 @@ var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
             ar[i] = from[i];
         }
     }
-    return to.concat(ar || from);
+    return to.concat(ar || Array.prototype.slice.call(from));
 };
 var _a, _b, _c, _d, _e, _f, _g;
 function foo(x, y) {