Generate branded primitives instead of unknown type for opaque types …

…without super type and type parameters Summary: Changelog: [Internal] - Added generation of branded primitives instead of unknown type for opaque types without super type and type parameters Reviewed By: pieterv Differential Revision: D70564934 fbshipit-source-id: b2d302219141f5175777b419fb577dd6a031008c
facebook · Mar 5, 2025 · 2199086 · 2199086
1 parent 7f86010
commit 2199086
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Showing 3 changed files with 46 additions and 2 deletions.
diff --git a/...pi-translator/__tests__/flowDefToTSDef/fixtures/opaque-type/declare/translate-result.shot b/...pi-translator/__tests__/flowDefToTSDef/fixtures/opaque-type/declare/translate-result.shot
@@ -11,6 +11,6 @@ exports[`flowDefToTSDef opaque-type/declare 1`] = `
  * @format
  */
 
-declare type T = unknown;
+declare type T = symbol & {__T__: string};
 "
 `;
diff --git a/...s/flow-api-translator/__tests__/flowDefToTSDef/fixtures/opaque-type/translate-result.shot b/...s/flow-api-translator/__tests__/flowDefToTSDef/fixtures/opaque-type/translate-result.shot
@@ -11,6 +11,6 @@ exports[`flowDefToTSDef opaque-type 1`] = `
  * @format
  */
 
-declare type T = unknown;
+declare type T = symbol & {__T__: string};
 "
 `;
diff --git a/tools/hermes-parser/js/flow-api-translator/src/flowDefToTSDef.js b/tools/hermes-parser/js/flow-api-translator/src/flowDefToTSDef.js
@@ -1709,6 +1709,50 @@ const getTransforms = (
       // TODO - we could simulate this in a variety of ways
       // Examples - https://basarat.gitbook.io/typescript/main-1/nominaltyping
 
+      if (node.supertype == null && node.typeParameters == null) {
+        const name = `__${node.id.name}__`;
+        return {
+          type: 'TSTypeAliasDeclaration',
+          loc: DUMMY_LOC,
+          declare: true,
+          id: transform.Identifier(node.id, false),
+          typeAnnotation: {
+            type: 'TSIntersectionType',
+            types: [
+              {
+                type: 'TSSymbolKeyword',
+                loc: DUMMY_LOC,
+              },
+              {
+                type: 'TSTypeLiteral',
+                loc: DUMMY_LOC,
+                members: [
+                  {
+                    type: 'TSPropertySignature',
+                    computed: false,
+                    loc: DUMMY_LOC,
+                    key: {
+                      type: 'Identifier',
+                      name: name,
+                      loc: DUMMY_LOC,
+                    },
+                    typeAnnotation: {
+                      type: 'TSTypeAnnotation',
+                      loc: DUMMY_LOC,
+                      typeAnnotation: {
+                        type: 'TSStringKeyword',
+                        loc: DUMMY_LOC,
+                      },
+                    },
+                  },
+                ],
+              },
+            ],
+            loc: DUMMY_LOC,
+          },
+        };
+      }
+
       return {
         type: 'TSTypeAliasDeclaration',
         loc: DUMMY_LOC,