Use information from contextual type in hovers/quick info (#2073)

Author: DanielRosenwasser

internal/fourslash/_scripts/failingTests.txt

@@ -454,7 +454,6 @@ TestQuickInfoForTypeParameterInTypeAlias1
 TestQuickInfoForTypeParameterInTypeAlias2
 TestQuickInfoForTypeofParameter
 TestQuickInfoForUMDModuleAlias
-TestQuickInfoFromContextualType
 TestQuickInfoFunctionKeyword
 TestQuickInfoGenerics
 TestQuickInfoGetterSetter
@@ -471,7 +470,6 @@ TestQuickInfoJsDocNonDiscriminatedUnionSharedProp
 TestQuickInfoJsdocTypedefMissingType
 TestQuickInfoMappedSpreadTypes
 TestQuickInfoMappedType
-TestQuickInfoMappedTypeMethods
 TestQuickInfoMappedTypeRecursiveInference
 TestQuickInfoModuleVariables
 TestQuickInfoNarrowedTypeOfAliasSymbol
@@ -526,7 +524,6 @@ TestQuickInfoTypeError
 TestQuickInfoTypeOfThisInStatics
 TestQuickInfoTypeOnlyNamespaceAndClass
 TestQuickInfoUnionOfNamespaces
-TestQuickInfoUnion_discriminated
 TestQuickInfoWidenedTypes
 TestQuickInfo_notInsideComment
 TestQuickInforForSucessiveInferencesIsNotAny

internal/fourslash/tests/gen/quickInfoFromContextualType_test.go

@@ -9,7 +9,7 @@ import (
 
 func TestQuickInfoFromContextualType(t *testing.T) {
 	t.Parallel()
-	t.Skip()
+
 	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
 	const content = `// @Filename: quickInfoExportAssignmentOfGenericInterface_0.ts
 interface I {

internal/fourslash/tests/gen/quickInfoMappedTypeMethods_test.go

@@ -9,7 +9,7 @@ import (
 
 func TestQuickInfoMappedTypeMethods(t *testing.T) {
 	t.Parallel()
-	t.Skip()
+
 	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
 	const content = `type M = { [K in 'one']: any };
 const x: M = {

internal/fourslash/tests/gen/quickInfoUnion_discriminated_test.go

@@ -9,7 +9,7 @@ import (
 
 func TestQuickInfoUnion_discriminated(t *testing.T) {
 	t.Parallel()
-	t.Skip()
+
 	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
 	const content = `// @Filename: quickInfoJsDocTags.ts
 type U = A | B;

internal/ls/hover.go

@@ -28,7 +28,8 @@ func (l *LanguageService) ProvideHover(ctx context.Context, documentURI lsproto.
 	c, done := program.GetTypeCheckerForFile(ctx, file)
 	defer done()
 	rangeNode := getNodeForQuickInfo(node)
-	quickInfo, documentation := l.getQuickInfoAndDocumentationForSymbol(c, c.GetSymbolAtLocation(node), rangeNode, contentFormat)
+	symbol := getSymbolAtLocationForQuickInfo(c, node)
+	quickInfo, documentation := l.getQuickInfoAndDocumentationForSymbol(c, symbol, rangeNode, contentFormat)
 	if quickInfo == "" {
 		return lsproto.HoverOrNull{}, nil
 	}
@@ -282,6 +283,17 @@ func getNodeForQuickInfo(node *ast.Node) *ast.Node {
 	return node
 }
 
+func getSymbolAtLocationForQuickInfo(c *checker.Checker, node *ast.Node) *ast.Symbol {
+	if objectElement := getContainingObjectLiteralElement(node); objectElement != nil {
+		if contextualType := c.GetContextualType(objectElement.Parent, checker.ContextFlagsNone); contextualType != nil {
+			if properties := c.GetPropertySymbolsFromContextualType(objectElement, contextualType, false /*unionSymbolOk*/); len(properties) == 1 {
+				return properties[0]
+			}
+		}
+	}
+	return c.GetSymbolAtLocation(node)
+}
+
 func inConstructorContext(node *ast.Node) bool {
 	if node.Kind == ast.KindConstructorKeyword {
 		return true