From f2896e0596f30b6e7e8ca6d275e918eb8fa708b4 Mon Sep 17 00:00:00 2001
From: Anders Kaseorg <andersk@mit.edu>
Date: Thu, 31 Oct 2024 12:08:22 -0700
Subject: [PATCH] fix: Preserve type members of namespace in re-exported module
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Previously we would generate `declare const …: typeof …` which
declares an object with the same value members but none of the type
members.

Fixes #322.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
 src/transform/NamespaceFixer.ts                         | 3 +++
 src/transform/Transformer.ts                            | 6 ++++++
 tests/testcases/re-export-namespace-inner/expected.d.ts | 9 +++++++++
 tests/testcases/re-export-namespace-inner/index.d.ts    | 2 ++
 tests/testcases/re-export-namespace-inner/mod.d.ts      | 5 +++++
 5 files changed, 25 insertions(+)
 create mode 100644 tests/testcases/re-export-namespace-inner/expected.d.ts
 create mode 100644 tests/testcases/re-export-namespace-inner/index.d.ts
 create mode 100644 tests/testcases/re-export-namespace-inner/mod.d.ts

diff --git a/src/transform/NamespaceFixer.ts b/src/transform/NamespaceFixer.ts
index 5cd8abe..fb58e07 100644
--- a/src/transform/NamespaceFixer.ts
+++ b/src/transform/NamespaceFixer.ts
@@ -197,6 +197,9 @@ export class NamespaceFixer {
             const typeParams = renderTypeParams(generics);
             code += `type ${ns.name}_${exportedName}${typeParams.in} = ${localName}${typeParams.out};\n`;
             code += `declare const ${ns.name}_${exportedName}: typeof ${localName};\n`;
+          } else if (type === "namespace") {
+            // namespaces may contain both types and values
+            code += `import ${ns.name}_${exportedName} = ${localName};\n`;
           } else {
             // functions and vars are just values
             code += `declare const ${ns.name}_${exportedName}: typeof ${localName};\n`;
diff --git a/src/transform/Transformer.ts b/src/transform/Transformer.ts
index c6021b4..f796a1f 100644
--- a/src/transform/Transformer.ts
+++ b/src/transform/Transformer.ts
@@ -250,6 +250,12 @@ class Transformer {
 
   convertImportDeclaration(node: ts.ImportDeclaration | ts.ImportEqualsDeclaration) {
     if (ts.isImportEqualsDeclaration(node)) {
+      if (ts.isEntityName(node.moduleReference)) {
+        const scope = this.createDeclaration(node, node.name);
+        scope.pushReference(scope.convertEntityName(node.moduleReference));
+        return;
+      }
+
       // assume its like `import default`
       if (!ts.isExternalModuleReference(node.moduleReference)) {
         throw new UnsupportedSyntaxError(node, "ImportEquals should have a literal source.");
diff --git a/tests/testcases/re-export-namespace-inner/expected.d.ts b/tests/testcases/re-export-namespace-inner/expected.d.ts
new file mode 100644
index 0000000..b319b42
--- /dev/null
+++ b/tests/testcases/re-export-namespace-inner/expected.d.ts
@@ -0,0 +1,9 @@
+declare namespace inner {
+  type Ty = number;
+  const num: number;
+}
+import mod_d_inner = inner;
+declare namespace mod_d {
+  export { mod_d_inner as inner };
+}
+export { mod_d as outer };
diff --git a/tests/testcases/re-export-namespace-inner/index.d.ts b/tests/testcases/re-export-namespace-inner/index.d.ts
new file mode 100644
index 0000000..c859b6c
--- /dev/null
+++ b/tests/testcases/re-export-namespace-inner/index.d.ts
@@ -0,0 +1,2 @@
+import * as outer from "./mod";
+export { outer };
diff --git a/tests/testcases/re-export-namespace-inner/mod.d.ts b/tests/testcases/re-export-namespace-inner/mod.d.ts
new file mode 100644
index 0000000..6119a54
--- /dev/null
+++ b/tests/testcases/re-export-namespace-inner/mod.d.ts
@@ -0,0 +1,5 @@
+declare namespace inner {
+  type Ty = number;
+  const num: number;
+}
+export { inner };