Fix 7304: show correct quickinfo on "this" in type position (microsoft#8508)

* Show correct quickinfo when using this in type position * Split quickinfo test into smaller files and add test case

Author: yuit

src/compiler/checker.ts

@@ -5211,6 +5211,7 @@ namespace ts {
  case SyntaxKind.NullKeyword:
  return nullType;
  case SyntaxKind.ThisType:
+ case SyntaxKind.ThisKeyword:
  return getTypeFromThisTypeNode(node);
  case SyntaxKind.StringLiteralType:
  return getTypeFromStringLiteralTypeNode(<StringLiteralTypeNode>node);
@@ -12509,7 +12510,7 @@ namespace ts {
 
  // Checks an expression and returns its type. The contextualMapper parameter serves two purposes: When
  // contextualMapper is not undefined and not equal to the identityMapper function object it indicates that the
- // expression is being inferentially typed (section 4.12.2 in spec) and provides the type mapper to use in
+ // expression is being inferentially typed (section 4.15.2 in spec) and provides the type mapper to use in
  // conjunction with the generic contextual type. When contextualMapper is equal to the identityMapper function
  // object, it serves as an indicator that all contained function and arrow expressions should be considered to
  // have the wildcard function type; this form of type check is used during overload resolution to exclude

src/compiler/utilities.ts

@@ -1056,6 +1056,7 @@ namespace ts {
 
  export function isExpression(node: Node): boolean {
  switch (node.kind) {
+ case SyntaxKind.ThisKeyword:
  case SyntaxKind.SuperKeyword:
  case SyntaxKind.NullKeyword:
  case SyntaxKind.TrueKeyword:

tests/cases/fourslash/quickInfoOnThis.ts

@@ -5,6 +5,7 @@
 ////function wrapper(wrapped: { (): void; }) { }
 ////class Foo {
 //// n: number;
+//// prop1: th/*0*/is;
 //// public explicitThis(this: this) {
 //// wrapper(
 //// function explicitVoid(this: void) {
@@ -20,43 +21,9 @@
 //// console.log(th/*6*/is);
 //// }
 ////}
-////class Bar<T> {
-//// public explicitThis(this: this) {
-//// console.log(th/*7*/is);
-//// }
-//// public explicitClass(this: Bar<T>) {
-//// console.log(thi/*8*/s);
-//// }
-////}
-////
-////function implicitAny(x: number): void {
-//// return th/*9*/is;
-////}
-////function explicitVoid(th/*10*/is: void, x: number): void {
-//// return th/*11*/is;
-////}
-////function explicitInterface(th/*12*/is: Restricted): void {
-//// console.log(thi/*13*/s);
-////}
-////function explicitLiteral(th/*14*/is: { n: number }): void {
-//// console.log(th/*15*/is);
-////}
-////
-////interface ContextualInterface {
-//// m: number;
-//// method(this: this, n: number);
-////}
-////let o: ContextualInterface = {
-//// m: 12,
-//// method(n) {
-//// let x = this/*16*/.m;
-//// }
-////}
-////interface ContextualInterface2 {
-//// (this: void, n: number): void;
-////}
-////let contextualInterface2: ContextualInterface2 = function (th/*17*/is, n) { }
 
+goTo.marker('0');
+verify.quickInfoIs('this: this');
 goTo.marker('1');
 verify.quickInfoIs('void');
 goTo.marker('2');
@@ -68,28 +35,4 @@ verify.quickInfoIs('this: Restricted');
 goTo.marker('5');
 verify.quickInfoIs('(parameter) this: Foo');
 goTo.marker('6');
-verify.quickInfoIs('this: Foo');
-goTo.marker('7');
-verify.quickInfoIs('this: this');
-goTo.marker('8');
-verify.quickInfoIs('this: Bar<T>');
-goTo.marker('9');
-verify.quickInfoIs('any');
-goTo.marker('10');
-verify.quickInfoIs('(parameter) this: void');
-goTo.marker('11');
-verify.quickInfoIs('void');
-goTo.marker('12');
-verify.quickInfoIs('(parameter) this: Restricted');
-goTo.marker('13');
-verify.quickInfoIs('this: Restricted');
-goTo.marker('14');
-
-verify.quickInfoIs('(parameter) this: {\n n: number;\n}');
-goTo.marker('15');
-verify.quickInfoIs('this: {\n n: number;\n}');
-
-goTo.marker('16');
-verify.quickInfoIs('this: ContextualInterface');
-goTo.marker('17');
-verify.quickInfoIs('(parameter) this: void');
+verify.quickInfoIs('this: Foo');

tests/cases/fourslash/quickInfoOnThis2.ts

@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+////class Bar<T> {
+//// public explicitThis(this: this) {
+//// console.log(th/*1*/is);
+//// }
+//// public explicitClass(this: Bar<T>) {
+//// console.log(thi/*2*/s);
+//// }
+////}
+
+goTo.marker('1');
+verify.quickInfoIs('this: this');
+goTo.marker('2');
+verify.quickInfoIs('this: Bar<T>');

tests/cases/fourslash/quickInfoOnThis3.ts

@@ -0,0 +1,32 @@
+/// <reference path='fourslash.ts' />
+////interface Restricted {
+//// n: number;
+////}
+////function implicitAny(x: number): void {
+//// return th/*1*/is;
+////}
+////function explicitVoid(th/*2*/is: void, x: number): void {
+//// return th/*3*/is;
+////}
+////function explicitInterface(th/*4*/is: Restricted): void {
+//// console.log(thi/*5*/s);
+////}
+////function explicitLiteral(th/*6*/is: { n: number }): void {
+//// console.log(th/*7*/is);
+////}
+
+goTo.marker('1');
+verify.quickInfoIs('any');
+goTo.marker('2');
+verify.quickInfoIs('(parameter) this: void');
+goTo.marker('3');
+verify.quickInfoIs('void');
+goTo.marker('4');
+verify.quickInfoIs('(parameter) this: Restricted');
+goTo.marker('5');
+verify.quickInfoIs('this: Restricted');
+goTo.marker('6');
+
+verify.quickInfoIs('(parameter) this: {\n n: number;\n}');
+goTo.marker('7');
+verify.quickInfoIs('this: {\n n: number;\n}');

tests/cases/fourslash/quickInfoOnThis4.ts

@@ -0,0 +1,20 @@
+/// <reference path='fourslash.ts' />
+////interface ContextualInterface {
+//// m: number;
+//// method(this: this, n: number);
+////}
+////let o: ContextualInterface = {
+//// m: 12,
+//// method(n) {
+//// let x = this/*1*/.m;
+//// }
+////}
+////interface ContextualInterface2 {
+//// (this: void, n: number): void;
+////}
+////let contextualInterface2: ContextualInterface2 = function (th/*2*/is, n) { }
+
+goTo.marker('1');
+verify.quickInfoIs('this: ContextualInterface');
+goTo.marker('2');
+verify.quickInfoIs('(parameter) this: void');