feat(43963): change var to a parameter in destructured function parameters (microsoft#44767)

Author: a-tarasyuk

src/services/utilities.ts

@@ -2059,7 +2059,9 @@ namespace ts {
     // Display-part writer helpers
     // #region
     export function isFirstDeclarationOfSymbolParameter(symbol: Symbol) {
-        return symbol.declarations && symbol.declarations.length > 0 && symbol.declarations[0].kind === SyntaxKind.Parameter;
+        const declaration = symbol.declarations ? firstOrUndefined(symbol.declarations) : undefined;
+        return !!findAncestor(declaration, n =>
+            isParameter(n) ? true : isBindingElement(n) || isObjectBindingPattern(n) || isArrayBindingPattern(n) ? false : "quit");
     }
 
     const displayPartWriter = getDisplayPartWriter();

tests/cases/fourslash/findAllReferencesDynamicImport3.ts

@@ -8,7 +8,7 @@ const [r0Def, r0, r1Def, r1]  = test.ranges();
 verify.referenceGroups(r0, [{ definition: "function bar(): string", ranges: [r0, r1] }]);
 verify.referenceGroups(r1, [
     { definition: "function bar(): string", ranges: [r0] },
-    { definition: "var bar: () => string", ranges: [r1] },
+    { definition: "(parameter) bar: () => string", ranges: [r1] },
 ]);
 verify.renameLocations(r0, [r0, { range: r1, suffixText: ": bar" }]);
 verify.renameLocations(r1, [{ range: r1, prefixText: "bar: " }])

tests/cases/fourslash/findAllRefsObjectBindingElementPropertyName04.ts

@@ -16,6 +16,6 @@ const [r0Def, r0, r1Def, r1, r2Def, r2, r3] = test.ranges();
 verify.referenceGroups([r0, r1], [{ definition: "(property) I.property1: number", ranges: [r0, r1, r2] }]);
 verify.referenceGroups(r2, [
     { definition: "(property) I.property1: number", ranges: [r0, r1] },
-    { definition: "var property1: number", ranges: [r2, r3] },
+    { definition: "(parameter) property1: number", ranges: [r2, r3] },
 ]);
-verify.referenceGroups(r3, [{ definition: "var property1: number", ranges: [r2, r3] }]);
+verify.referenceGroups(r3, [{ definition: "(parameter) property1: number", ranges: [r2, r3] }]);

tests/cases/fourslash/parameterWithDestructuring.ts

@@ -1,19 +1,18 @@
 /// <reference path='fourslash.ts'/>
 
-// Repros from issues #4949 and #4818
-
-////const result = [{ foo: 'hello' }]
-////    .map(({ /*1*/foo }) => /*2*/foo)
-////    .map(foo => foo);
+////const result = [{ a: 'hello' }]
+////    .map(({ /*1*/a }) => /*2*/a)
+////    .map(a => a);
 ////
-////const f = (foo: (bar: string[]) => void) => { };
+////const f1 = (a: (b: string[]) => void) => {};
+////f1(([a, b]) => { /*3*/a.charAt(0); });
 ////
-////f(([a, b]) => {
-////    /*3*/a.charAt(0); // Not okay: inferred as `any`
-////});
+////function f2({/*4*/a }: { a: string; }, [/*5*/b]: [string]) {}
 
 verify.quickInfos({
-    1: "var foo: string",
-    2: "var foo: string",
-    3: "var a: string"
+    1: "(parameter) a: string",
+    2: "(parameter) a: string",
+    3: "(parameter) a: string",
+    4: "(parameter) a: string",
+    5: "(parameter) b: string"
 });

tests/cases/fourslash/parameterWithNestedDestructuring.ts

@@ -1,9 +1,13 @@
 /// <reference path='fourslash.ts'/>
 
-////[[{foo: 'hello', bar: [1]}]]
-////  .map(([{foo, bar: [baz]}]) => /*1*/foo + /*2*/baz);
+////[[{ a: 'hello', b: [1] }]]
+////  .map(([{ a, b: [c] }]) => /*1*/a + /*2*/c);
+
+////function f([[/*3*/a]]: [[string]], { b1: { /*4*/b2 } }: { b1: { b2: string; } }) {}
 
 verify.quickInfos({
-    1: "var foo: string",
-    2: "var baz: number"
+    1: "(parameter) a: string",
+    2: "(parameter) c: number",
+    3: "(parameter) a: string",
+    4: "(parameter) b2: string"
 });

tests/cases/fourslash/quickInfoForContextuallyTypedIife.ts

@@ -9,13 +9,13 @@
 ////((a/*9*/, b/*10*/, c/*11*/) => [a/*12*/,b/*13*/,c/*14*/])("foo", 101, false);
 
 verify.quickInfos({
-    1: "var q: number",
-    2: "var qq: number",
+    1: "(parameter) q: number",
+    2: "(parameter) qq: number",
     3: "(parameter) x: number",
-    4: "var p: number",
-    5: "var q: number",
-    6: "var qq: number",
-    7: "var p: number",
+    4: "(parameter) p: number",
+    5: "(parameter) q: number",
+    6: "(parameter) qq: number",
+    7: "(parameter) p: number",
     8: "(parameter) x: number",
     9: "(parameter) a: string",
     10: "(parameter) b: number",