From 4879f9da999c2919a60e5bd60afd89042adc7ea7 Mon Sep 17 00:00:00 2001
From: Rohit Nair P <rohitnairmuttathethu@gmail.com>
Date: Mon, 30 Mar 2026 01:34:18 +0530
Subject: [PATCH] fix: improve duplicate module import error message (#18016)

## Description
**While investigating the compiler analysis phase for errors or missing
lines, I located an explicit `TODO fix the message here` comment in the
source code
(`packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js`).**

### Triggering Code
```svelte
<script module>
	import { foo } from './somewhere.js';
</script>

<script>
	let foo = 'conflict'; // Triggers the duplicate module import error
</script>
```

## The Bug
When a component author creates a local `let` declaration in the
instance `<script>` block that shadows a variable imported in the
`<script module>` block, the compiler emits a
`declaration_duplicate_module_import` error.

However, the error message text was misleading. It stated:
```diff
- Cannot declare a variable with the same name as an import inside `<script module>`
+ Cannot declare a variable with the same name as an import from `<script module>`
```

This incorrectly implies that the duplicate declaration itself is
happening *inside* the module script block, rather than colliding with
an import *from* that block.

## Changes Made

| Action | Target (File / Function) | Description |
| :--- | :--- | :--- |
| **Template Fix** | `packages/svelte/messages/compile-errors/script.md`
| Changed "inside" to "from" to accurately reflect the nature of the
shadow collision. |
| **Regenerated Errors** | `packages/svelte/src/compiler/errors.js` |
Ran `pnpm generate` to apply the updated markdown template into the
dictionary list. |
| **Removed TODO** | `ensure_no_module_import_conflict` function |
Removed the original `// TODO fix the message here` notation from the
validator. |
| **Test Adjustments** | `illegal-variable-declaration/errors.json` |
Updated the validator test suite snapshots to assert against the correct
error message format. |

## Validation Results

* The error correctly throws when a user replicates this component
structure.
* Vitest suite `tests/validator/test.ts` successfully asserts the new,
clearer message.

---
### Before submitting the PR, please make sure you do the following

- [x] It's really useful if your PR references an issue where it is
discussed ahead of time. In many cases, features are absent for a
reason. For large changes, please create an RFC:
https://github.com/sveltejs/rfcs
- [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`.
- [x] This message body should clearly illustrate what problems it
solves.
- [x] Ideally, include a test that fails without this PR but passes with
it.
- [x] If this PR changes code within `packages/svelte/src`, add a
changeset (`npx changeset`).

### Tests and linting

- [x] Run the tests with `pnpm test` and lint the project with `pnpm
lint`

# THANK YOU
---
 .changeset/quiet-cats-purr.md                                | 5 +++++
 documentation/docs/98-reference/.generated/compile-errors.md | 2 +-
 packages/svelte/messages/compile-errors/script.md            | 2 +-
 packages/svelte/src/compiler/errors.js                       | 4 ++--
 .../src/compiler/phases/2-analyze/visitors/shared/utils.js   | 1 -
 .../samples/illegal-variable-declaration/errors.json         | 2 +-
 6 files changed, 10 insertions(+), 6 deletions(-)
 create mode 100644 .changeset/quiet-cats-purr.md

diff --git a/.changeset/quiet-cats-purr.md b/.changeset/quiet-cats-purr.md
new file mode 100644
index 0000000000..0cb486cfce
--- /dev/null
+++ b/.changeset/quiet-cats-purr.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: improve duplicate module import error message
diff --git a/documentation/docs/98-reference/.generated/compile-errors.md b/documentation/docs/98-reference/.generated/compile-errors.md
index 1c874436de..01b2dd1494 100644
--- a/documentation/docs/98-reference/.generated/compile-errors.md
+++ b/documentation/docs/98-reference/.generated/compile-errors.md
@@ -396,7 +396,7 @@ Invalid selector
 ### declaration_duplicate_module_import
 
 ```
-Cannot declare a variable with the same name as an import inside `<script module>`
+Cannot declare a variable with the same name as an import from `<script module>`
 ```
 
 ### derived_invalid_export
diff --git a/packages/svelte/messages/compile-errors/script.md b/packages/svelte/messages/compile-errors/script.md
index 5c1080aced..743fe31fde 100644
--- a/packages/svelte/messages/compile-errors/script.md
+++ b/packages/svelte/messages/compile-errors/script.md
@@ -16,7 +16,7 @@
 
 ## declaration_duplicate_module_import
 
-> Cannot declare a variable with the same name as an import inside `<script module>`
+> Cannot declare a variable with the same name as an import from `<script module>`
 
 ## derived_invalid_export
 
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index c28c737d7f..976925d181 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -117,12 +117,12 @@ export function declaration_duplicate(node, name) {
 }
 
 /**
- * Cannot declare a variable with the same name as an import inside `<script module>`
+ * Cannot declare a variable with the same name as an import from `<script module>`
  * @param {null | number | NodeLike} node
  * @returns {never}
  */
 export function declaration_duplicate_module_import(node) {
-	e(node, 'declaration_duplicate_module_import', `Cannot declare a variable with the same name as an import inside \`<script module>\`\nhttps://svelte.dev/e/declaration_duplicate_module_import`);
+	e(node, 'declaration_duplicate_module_import', `Cannot declare a variable with the same name as an import from \`<script module>\`\nhttps://svelte.dev/e/declaration_duplicate_module_import`);
 }
 
 /**
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js
index cc4376a0c2..35116d715a 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js
@@ -161,7 +161,6 @@ export function ensure_no_module_import_conflict(node, state) {
 			state.scope === state.analysis.instance.scope &&
 			state.analysis.module.scope.get(id.name)?.declaration_kind === 'import'
 		) {
-			// TODO fix the message here
 			e.declaration_duplicate_module_import(node.id);
 		}
 	}
diff --git a/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json b/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json
index 850880e744..cf413c39df 100644
--- a/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json
+++ b/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "declaration_duplicate_module_import",
-		"message": "Cannot declare a variable with the same name as an import inside `<script module>`",
+		"message": "Cannot declare a variable with the same name as an import from `<script module>`",
 		"start": {
 			"line": 12,
 			"column": 5