feat: downlevel template literal types < 4.1 (#82)

https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-1.html#template-literal-types Closes #72 Co-authored-by: Jeremy Jonas <[email protected]>
sandersn · Oct 19, 2022 · fb8f2de · fb8f2de
1 parent 5188cd4
commit fb8f2de
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Showing 16 changed files with 38 additions and 1 deletion.
diff --git a/baselines/reference/ts3.4/test.d.ts b/baselines/reference/ts3.4/test.d.ts
@@ -69,3 +69,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts3.5/test.d.ts b/baselines/reference/ts3.5/test.d.ts
@@ -69,3 +69,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts3.6/test.d.ts b/baselines/reference/ts3.6/test.d.ts
@@ -71,3 +71,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts3.7/test.d.ts b/baselines/reference/ts3.7/test.d.ts
@@ -71,3 +71,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts3.8/test.d.ts b/baselines/reference/ts3.8/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts3.9/test.d.ts b/baselines/reference/ts3.9/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts4.0/test.d.ts b/baselines/reference/ts4.0/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = string;
diff --git a/baselines/reference/ts4.1/test.d.ts b/baselines/reference/ts4.1/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/baselines/reference/ts4.2/test.d.ts b/baselines/reference/ts4.2/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/baselines/reference/ts4.3/test.d.ts b/baselines/reference/ts4.3/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/baselines/reference/ts4.4/test.d.ts b/baselines/reference/ts4.4/test.d.ts
@@ -72,3 +72,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/baselines/reference/ts4.5/test.d.ts b/baselines/reference/ts4.5/test.d.ts
@@ -69,3 +69,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/baselines/reference/ts4.6/test.d.ts b/baselines/reference/ts4.6/test.d.ts
@@ -69,3 +69,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/baselines/reference/ts4.7/test.d.ts b/baselines/reference/ts4.7/test.d.ts
@@ -69,3 +69,5 @@ export declare const foo: {
     };
 };
 export type IR = IteratorResult<number, string>;
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;
diff --git a/index.js b/index.js
@@ -83,6 +83,12 @@ function doTransform(checker, targetVersion, k) {
       }
     }
 
+    if (semver.lt(targetVersion, "4.1.0") && n.kind === ts.SyntaxKind.TemplateLiteralType) {
+      // TemplateLiteralType added in 4.2
+      // https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-1.html#template-literal-types
+      return ts.factory.createKeywordTypeNode(ts.SyntaxKind.StringKeyword)
+    }
+
     if (semver.lt(targetVersion, "3.6.0") && ts.isGetAccessor(n)) {
       // get x(): number => x: number
       let flags = ts.getCombinedModifierFlags(n);

diff --git a/test/test.d.ts b/test/test.d.ts
@@ -74,4 +74,7 @@ export declare const foo: {
     };
 };
 
-export type IR = IteratorResult<number, string>;
+export type IR = IteratorResult<number, string>;
+
+/** Template Literal - supported since 4.1 < should be StringKeyword */
+export type TTemplateLiteral = `${string}abc${string}`;