Merge branch 'master' into builderAPI

Author: sheetalkamat

README.md

@@ -1,11 +1,13 @@
+
+# TypeScript
+
+[![Join the chat at https://gitter.im/Microsoft/TypeScript](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/Microsoft/TypeScript?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
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-# TypeScript
 
-[![Join the chat at https://gitter.im/Microsoft/TypeScript](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/Microsoft/TypeScript?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 [TypeScript](https://www.typescriptlang.org/) is a language for application-scale JavaScript. TypeScript adds optional types to JavaScript that support tools for large-scale JavaScript applications for any browser, for any host, on any OS. TypeScript compiles to readable, standards-based JavaScript. Try it out at the [playground](https://www.typescriptlang.org/play/), and stay up to date via [our blog](https://blogs.msdn.microsoft.com/typescript) and [Twitter account](https://twitter.com/typescript).
 

src/compiler/checker.ts

@@ -2546,6 +2546,8 @@ namespace ts {
         Shared         = 1 << 10, // Referenced as antecedent more than once
         PreFinally     = 1 << 11, // Injected edge that links pre-finally label and pre-try flow
         AfterFinally   = 1 << 12, // Injected edge that links post-finally flow with the rest of the graph
+        /** @internal */
+        Cached         = 1 << 13, // Indicates that at least one cross-call cache entry exists for this node, even if not a loop participant
         Label = BranchLabel | LoopLabel,
         Condition = TrueCondition | FalseCondition
     }
@@ -3967,6 +3969,8 @@ namespace ts {
         StructuredOrInstantiable = StructuredType | Instantiable,
         /* @internal */
         ObjectFlagsType = Nullable | Never | Object | Union | Intersection,
+        /* @internal */
+        Simplifiable = IndexedAccess | Conditional | Substitution,
         // 'Narrowable' types are types where narrowing actually narrows.
         // This *should* be every type other than null, undefined, void, and never
         Narrowable = Any | Unknown | StructuredOrInstantiable | StringLike | NumberLike | BigIntLike | BooleanLike | ESSymbol | UniqueESSymbol | NonPrimitive,
@@ -4339,8 +4343,8 @@ namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
         /* @internal */
         resolvedInferredTrueType?: Type; // The `trueType` instantiated with the `combinedMapper`, if present
         /* @internal */
@@ -4425,15 +4429,16 @@ namespace ts {
     export type TypeMapper = (t: TypeParameter) => Type;
 
     export const enum InferencePriority {
-        NakedTypeVariable           = 1 << 0,  // Naked type variable in union or intersection type
-        HomomorphicMappedType       = 1 << 1,  // Reverse inference for homomorphic mapped type
-        MappedTypeConstraint        = 1 << 2,  // Reverse inference for mapped type
-        ReturnType                  = 1 << 3,  // Inference made from return type of generic function
-        LiteralKeyof                = 1 << 4,  // Inference made from a string literal to a keyof T
-        NoConstraints               = 1 << 5,  // Don't infer from constraints of instantiable types
-        AlwaysStrict                = 1 << 6,  // Always use strict rules for contravariant inferences
-
-        PriorityImpliesCombination  = ReturnType | MappedTypeConstraint | LiteralKeyof,  // These priorities imply that the resulting type should be a combination of all candidates
+        NakedTypeVariable            = 1 << 0,  // Naked type variable in union or intersection type
+        HomomorphicMappedType        = 1 << 1,  // Reverse inference for homomorphic mapped type
+        PartialHomomorphicMappedType = 1 << 2,  // Partial reverse inference for homomorphic mapped type
+        MappedTypeConstraint         = 1 << 3,  // Reverse inference for mapped type
+        ReturnType                   = 1 << 4,  // Inference made from return type of generic function
+        LiteralKeyof                 = 1 << 5,  // Inference made from a string literal to a keyof T
+        NoConstraints                = 1 << 6,  // Don't infer from constraints of instantiable types
+        AlwaysStrict                 = 1 << 7,  // Always use strict rules for contravariant inferences
+
+        PriorityImpliesCombination = ReturnType | MappedTypeConstraint | LiteralKeyof,  // These priorities imply that the resulting type should be a combination of all candidates
     }
 
     /* @internal */

src/compiler/types.ts

@@ -1446,9 +1446,7 @@ type Extract<T, U> = T extends U ? T : never;
 /**
  * Construct a type with the properties of T except for those in type K.
  */
-type Omit<T, K extends keyof any> = {
-    [P in Exclude<keyof T, K>]: T[P]
-};
+type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;
 
 /**
  * Exclude null and undefined from T

src/lib/es5.d.ts

@@ -2391,8 +2391,8 @@ declare namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
     }
     interface SubstitutionType extends InstantiableType {
         typeVariable: TypeVariable;
@@ -2419,12 +2419,13 @@ declare namespace ts {
     enum InferencePriority {
         NakedTypeVariable = 1,
         HomomorphicMappedType = 2,
-        MappedTypeConstraint = 4,
-        ReturnType = 8,
-        LiteralKeyof = 16,
-        NoConstraints = 32,
-        AlwaysStrict = 64,
-        PriorityImpliesCombination = 28
+        PartialHomomorphicMappedType = 4,
+        MappedTypeConstraint = 8,
+        ReturnType = 16,
+        LiteralKeyof = 32,
+        NoConstraints = 64,
+        AlwaysStrict = 128,
+        PriorityImpliesCombination = 56
     }
     /** @deprecated Use FileExtensionInfo instead. */
     type JsFileExtensionInfo = FileExtensionInfo;

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -2391,8 +2391,8 @@ declare namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
     }
     interface SubstitutionType extends InstantiableType {
         typeVariable: TypeVariable;
@@ -2419,12 +2419,13 @@ declare namespace ts {
     enum InferencePriority {
         NakedTypeVariable = 1,
         HomomorphicMappedType = 2,
-        MappedTypeConstraint = 4,
-        ReturnType = 8,
-        LiteralKeyof = 16,
-        NoConstraints = 32,
-        AlwaysStrict = 64,
-        PriorityImpliesCombination = 28
+        PartialHomomorphicMappedType = 4,
+        MappedTypeConstraint = 8,
+        ReturnType = 16,
+        LiteralKeyof = 32,
+        NoConstraints = 64,
+        AlwaysStrict = 128,
+        PriorityImpliesCombination = 56
     }
     /** @deprecated Use FileExtensionInfo instead. */
     type JsFileExtensionInfo = FileExtensionInfo;