Type checking for tagged template expressions

src/compiler/core.ts

@@ -122,6 +122,17 @@ module ts {
         return result;
     }
 
+    /**
+     * Returns the last element of an array if non-empty, undefined otherwise.
+     */
+    export function lastOrUndefined<T>(array: T[]): T {
+        if (array.length === 0) {
+            return undefined;
+        }
+
+        return array[array.length - 1];
+    }
+
     export function binarySearch(array: number[], value: number): number {
         var low = 0;
         var high = array.length - 1;

src/compiler/parser.ts

@@ -567,7 +567,6 @@ module ts {
         return false;
     }
 
-
     export function isDeclaration(node: Node): boolean {
         switch (node.kind) {
             case SyntaxKind.TypeParameter:
@@ -796,6 +795,20 @@ module ts {
         return SyntaxKind.FirstTriviaToken <= token && token <= SyntaxKind.LastTriviaToken;
     }
 
+    export function isUnterminatedTemplateEnd(node: LiteralExpression) {
+        Debug.assert(node.kind === SyntaxKind.NoSubstitutionTemplateLiteral || node.kind === SyntaxKind.TemplateTail);
+        var sourceText = getSourceFileOfNode(node).text;
+
+        // If we're not at the EOF, we know we must be terminated.
+        if (node.end !== sourceText.length) {
+            return false;
+        }
+
+        // If we didn't end in a backtick, we must still be in the middle of a template.
+        // If we did, make sure that it's not the *initial* backtick.
+        return sourceText.charCodeAt(node.end - 1) !== CharacterCodes.backtick || node.text.length === 0;
+    }
+
     export function isModifier(token: SyntaxKind): boolean {
         switch (token) {
             case SyntaxKind.PublicKeyword:

src/compiler/types.ts

@@ -477,6 +477,8 @@ module ts {
         template: LiteralExpression | TemplateExpression;
     }
 
+    export type CallLikeExpression = CallExpression | NewExpression | TaggedTemplateExpression;
+
     export interface TypeAssertion extends Expression {
         type: TypeNode;
         operand: Expression;

src/lib/core.d.ts

@@ -484,6 +484,10 @@ declare var Number: {
     POSITIVE_INFINITY: number;
 }
 
+interface TemplateStringsArray extends Array<string> {
+    raw: string[];
+}
+
 interface Math {
     /** The mathematical constant e. This is Euler's number, the base of natural logarithms. */
     E: number;

tests/baselines/reference/noDefaultLib.errors.txt

@@ -1,10 +1,12 @@
 error TS2318: Cannot find global type 'Boolean'.
 error TS2318: Cannot find global type 'IArguments'.
+error TS2318: Cannot find global type 'TemplateStringsArray'.
 tests/cases/compiler/noDefaultLib.ts(4,11): error TS2317: Global type 'Array' must have 1 type parameter(s).
 
 
 !!! error TS2318: Cannot find global type 'Boolean'.
 !!! error TS2318: Cannot find global type 'IArguments'.
+!!! error TS2318: Cannot find global type 'TemplateStringsArray'.
 ==== tests/cases/compiler/noDefaultLib.ts (1 errors) ====
     /// <reference no-default-lib="true"/>
     var x;

tests/baselines/reference/parser509698.errors.txt

@@ -6,6 +6,7 @@ error TS2318: Cannot find global type 'Number'.
 error TS2318: Cannot find global type 'Object'.
 error TS2318: Cannot find global type 'RegExp'.
 error TS2318: Cannot find global type 'String'.
+error TS2318: Cannot find global type 'TemplateStringsArray'.
 
 
 !!! error TS2318: Cannot find global type 'Array'.
@@ -16,6 +17,7 @@ error TS2318: Cannot find global type 'String'.
 !!! error TS2318: Cannot find global type 'Object'.
 !!! error TS2318: Cannot find global type 'RegExp'.
 !!! error TS2318: Cannot find global type 'String'.
+!!! error TS2318: Cannot find global type 'TemplateStringsArray'.
 ==== tests/cases/conformance/parser/ecmascript5/RegressionTests/parser509698.ts (0 errors) ====
     /// <style requireSemi="on" />
     /// <reference no-default-lib="true"/>

tests/baselines/reference/project/noDefaultLib/amd/noDefaultLib.errors.txt

@@ -6,6 +6,7 @@ error TS2318: Cannot find global type 'Number'.
 error TS2318: Cannot find global type 'Object'.
 error TS2318: Cannot find global type 'RegExp'.
 error TS2318: Cannot find global type 'String'.
+error TS2318: Cannot find global type 'TemplateStringsArray'.
 test.ts(3,8): error TS2304: Cannot find name 'Array'.
 
 
@@ -17,6 +18,7 @@ test.ts(3,8): error TS2304: Cannot find name 'Array'.
 !!! error TS2318: Cannot find global type 'Object'.
 !!! error TS2318: Cannot find global type 'RegExp'.
 !!! error TS2318: Cannot find global type 'String'.
+!!! error TS2318: Cannot find global type 'TemplateStringsArray'.
 ==== test.ts (1 errors) ====
     /// <reference no-default-lib="true"/>
 

tests/baselines/reference/project/noDefaultLib/node/noDefaultLib.errors.txt

@@ -6,6 +6,7 @@ error TS2318: Cannot find global type 'Number'.
 error TS2318: Cannot find global type 'Object'.
 error TS2318: Cannot find global type 'RegExp'.
 error TS2318: Cannot find global type 'String'.
+error TS2318: Cannot find global type 'TemplateStringsArray'.
 test.ts(3,8): error TS2304: Cannot find name 'Array'.
 
 
@@ -17,6 +18,7 @@ test.ts(3,8): error TS2304: Cannot find name 'Array'.
 !!! error TS2318: Cannot find global type 'Object'.
 !!! error TS2318: Cannot find global type 'RegExp'.
 !!! error TS2318: Cannot find global type 'String'.
+!!! error TS2318: Cannot find global type 'TemplateStringsArray'.
 ==== test.ts (1 errors) ====
     /// <reference no-default-lib="true"/>
 

tests/baselines/reference/taggedTemplateStringsTypeArgumentInference.errors.txt

@@ -0,0 +1,190 @@
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(5,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(9,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(13,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(16,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(20,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(23,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(27,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(28,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(29,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(33,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(34,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(35,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(39,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(40,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(41,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(45,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(46,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(47,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(51,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(52,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(53,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(57,9): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(58,1): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(64,11): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(77,11): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(81,11): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(86,9): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(90,11): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(64,11): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
+  Type argument candidate 'string' is not a valid type argument because it is not a supertype of candidate 'number'.
+tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts(77,11): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
+  Type argument candidate '{ x: number; z: Date; }' is not a valid type argument because it is not a supertype of candidate '{ x: number; y: string; }'.
+
+
+==== tests/cases/conformance/es6/templates/taggedTemplateStringsTypeArgumentInference.ts (30 errors) ====
+
+
+    // Generic tag with one parameter
+    function noParams<T>(n: T) { }
+    noParams ``;
+    ~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with parameter which does not use type parameter
+    function noGenericParams<T>(n: string[]) { }
+    noGenericParams ``;
+    ~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with multiple type parameters and only one used in parameter type annotation
+    function someGenerics1a<T, U>(n: T, m: number) { }
+    someGenerics1a `${3}`;
+    ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    function someGenerics1b<T, U>(n: string[], m: U) { }
+    someGenerics1b `${3}`;
+    ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with argument of function type whose parameter is of type parameter type
+    function someGenerics2a<T>(strs: string[], n: (x: T) => void) { }
+    someGenerics2a `${(n: string) => n}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    function someGenerics2b<T, U>(strs: string[], n: (x: T, y: U) => void) { }
+    someGenerics2b `${ (n: string, x: number) => n }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with argument of function type whose parameter is not of type parameter type but body/return type uses type parameter
+    function someGenerics3<T>(strs: string[], producer: () => T) { }
+    someGenerics3 `${() => ''}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics3 `${() => undefined}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics3 `${() => 3}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // 2 parameter generic tag with argument 1 of type parameter type and argument 2 of function type whose parameter is of type parameter type
+    function someGenerics4<T, U>(strs: string[], n: T, f: (x: U) => void) { }
+    someGenerics4 `${4}${ () => null }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics4 `${''}${ () => 3 }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics4 `${ null }${ null }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // 2 parameter generic tag with argument 2 of type parameter type and argument 1 of function type whose parameter is of type parameter type
+    function someGenerics5<U, T>(strs: string[], n: T, f: (x: U) => void) { }
+    someGenerics5 `${ 4 } ${ () => null }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics5 `${ '' }${ () => 3 }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics5 `${null}${null}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with multiple arguments of function types that each have parameters of the same generic type
+    function someGenerics6<A>(strs: string[], a: (a: A) => A, b: (b: A) => A, c: (c: A) => A) { }
+    someGenerics6 `${ n => n }${ n => n}${ n => n}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics6 `${ n => n }${ n => n}${ n => n}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics6 `${ (n: number) => n }${ (n: number) => n }${ (n: number) => n }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with multiple arguments of function types that each have parameters of different generic type
+    function someGenerics7<A, B, C>(strs: string[], a: (a: A) => A, b: (b: B) => B, c: (c: C) => C) { }
+    someGenerics7 `${ n => n }${ n => n }${ n => n }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics7 `${ n => n }${ n => n }${ n => n }`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    someGenerics7 `${(n: number) => n}${ (n: string) => n}${ (n: number) => n}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with argument of generic function type
+    function someGenerics8<T>(strs: string[], n: T): T { return n; }
+    var x = someGenerics8 `${ someGenerics7 }`;
+            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    x `${null}${null}${null}`;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+
+    // Generic tag with multiple parameters of generic type passed arguments with no best common type
+    function someGenerics9<T>(strs: string[], a: T, b: T, c: T): T {
+        return null;
+    }
+    var a9a = someGenerics9 `${ '' }${ 0 }${ [] }`;
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+              ~~~~~~~~~~~~~
+!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
+!!! error TS2453:   Type argument candidate 'string' is not a valid type argument because it is not a supertype of candidate 'number'.
+    var a9a: {};
+
+    // Generic tag with multiple parameters of generic type passed arguments with multiple best common types
+    interface A91 {
+        x: number;
+        y?: string;
+    }
+    interface A92 {
+        x: number;
+        z?: Date;
+    }
+
+    var a9e = someGenerics9 `${ undefined }${ { x: 6, z: new Date() } }${ { x: 6, y: '' } }`;
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+              ~~~~~~~~~~~~~
+!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
+!!! error TS2453:   Type argument candidate '{ x: number; z: Date; }' is not a valid type argument because it is not a supertype of candidate '{ x: number; y: string; }'.
+    var a9e: {};
+
+    // Generic tag with multiple parameters of generic type passed arguments with a single best common type
+    var a9d = someGenerics9 `${ { x: 3 }}${ { x: 6 }}${ { x: 6 } }`;
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    var a9d: { x: number; };
+
+    // Generic tag with multiple parameters of generic type where one argument is of type 'any'
+    var anyVar: any;
+    var a = someGenerics9 `${ 7 }${ anyVar }${ 4 }`;
+            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    var a: any;
+
+    // Generic tag with multiple parameters of generic type where one argument is [] and the other is not 'any'
+    var arr = someGenerics9 `${ [] }${ null }${ undefined }`;
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
+    var arr: any[];
+
+