From 703b67b7e0bb649e1a1047d90de3e53291a9ddae Mon Sep 17 00:00:00 2001
From: Lukas Matejka <matejka-lukas@hotmail.de>
Date: Thu, 28 Aug 2025 21:29:56 +0200
Subject: [PATCH] Emit INVALID_TOKEN_IN_PLACEHOLDER instead of
 UNTERMINATED_CLOSING_BRACE when invalid token is in placeholder and update
 docs

---
 docs/guide/essentials/syntax.md               |   6 +-
 packages/message-compiler/src/tokenizer.ts    |  20 ++++
 .../test/tokenizer/named.test.ts              | 108 +++++++++++++-----
 3 files changed, 103 insertions(+), 31 deletions(-)

diff --git a/docs/guide/essentials/syntax.md b/docs/guide/essentials/syntax.md
index f000ac6c2..145d908d6 100644
--- a/docs/guide/essentials/syntax.md
+++ b/docs/guide/essentials/syntax.md
@@ -26,6 +26,10 @@ The locale messages is the resource specified by the `messages` option of `creat
 
 Named interpolation allows you to specify variables defined in JavaScript. In the locale message above, you can localize it by giving the JavaScript defined `msg` as a parameter to the translation function.
 
+The variable name inside `{}` must starts with a letter (a-z, A-Z) or an underscore (`_`), followed by any combination of letters, digits, underscores (`_`), hyphens (`-`), or dollar signs (`$`).
+
+Examples: `{msg}`, `{_userName}`, `{user-id}`, `{total$}`
+
 The following is an example of the use of `$t` in a template:
 
 ```html
@@ -267,7 +271,7 @@ In `message.greeting`, we use a named interpolation for `{count}` and link to `m
 
 The key `message.name` contains `{name}`, which will be interpolated with the passed `name` param.
 
-The `message.greeting` is linked to the locale message key `message.name`. 
+The `message.greeting` is linked to the locale message key `message.name`.
 
 ```html
 <p>{{ $t('message.greeting', { name: 'Alice', count: 5 }) }}</p>
diff --git a/packages/message-compiler/src/tokenizer.ts b/packages/message-compiler/src/tokenizer.ts
index 0ef63bf88..6f94bfe9b 100644
--- a/packages/message-compiler/src/tokenizer.ts
+++ b/packages/message-compiler/src/tokenizer.ts
@@ -484,6 +484,26 @@ export function createTokenizer(
       name += ch
     }
 
+    // Check if takeNamedIdentifierChar stoped because of invalid characters
+    const currentChar = scnr.currentChar()
+    if (
+      currentChar &&
+      currentChar !== '}' &&
+      currentChar !== EOF &&
+      currentChar !== SPACE &&
+      currentChar !== NEW_LINE &&
+      currentChar !== '\u3000'
+    ) {
+      const invalidPart = readInvalidIdentifier(scnr)
+      emitError(
+        CompileErrorCodes.INVALID_TOKEN_IN_PLACEHOLDER,
+        currentPosition(),
+        0,
+        name + invalidPart
+      )
+      return name + invalidPart
+    }
+
     if (scnr.currentChar() === EOF) {
       emitError(
         CompileErrorCodes.UNTERMINATED_CLOSING_BRACE,
diff --git a/packages/message-compiler/test/tokenizer/named.test.ts b/packages/message-compiler/test/tokenizer/named.test.ts
index c7c3bb3c6..7405000a8 100644
--- a/packages/message-compiler/test/tokenizer/named.test.ts
+++ b/packages/message-compiler/test/tokenizer/named.test.ts
@@ -2,13 +2,13 @@ import { format } from '@intlify/shared'
 import { CompileErrorCodes, errorMessages } from '../../src/errors'
 import {
   createTokenizer,
-  TokenTypes,
   ERROR_DOMAIN,
-  parse
+  parse,
+  TokenTypes
 } from '../../src/tokenizer'
 
-import type { TokenizeOptions } from '../../src/options'
 import type { CompileError } from '../../src/errors'
+import type { TokenizeOptions } from '../../src/options'
 
 test('basic', () => {
   const tokenizer = createTokenizer('hi {name} !')
@@ -645,32 +645,80 @@ describe('errors', () => {
       }
     ] as CompileError[])
   })
-  const items = [`$`, `-`]
-  for (const ch of items) {
-    test(`invalid '${ch}' in placeholder`, () => {
-      parse(`hi {${ch}} !`, options)
-      expect(errors).toEqual([
-        {
-          code: CompileErrorCodes.INVALID_TOKEN_IN_PLACEHOLDER,
-          domain: ERROR_DOMAIN,
-          message: format(
-            errorMessages[CompileErrorCodes.INVALID_TOKEN_IN_PLACEHOLDER],
-            ch
-          ),
-          location: {
-            start: {
-              line: 1,
-              offset: 4,
-              column: 5
-            },
-            end: {
-              line: 1,
-              offset: 5,
-              column: 6
-            }
-          }
+
+  test.each([
+    [
+      '$',
+      {
+        start: {
+          line: 1,
+          offset: 4,
+          column: 5
+        },
+        end: {
+          line: 1,
+          offset: 5,
+          column: 6
+        }
+      }
+    ],
+    [
+      '-',
+      {
+        start: {
+          line: 1,
+          offset: 4,
+          column: 5
+        },
+        end: {
+          line: 1,
+          offset: 5,
+          column: 6
+        }
+      }
+    ],
+    [
+      'àaa',
+      {
+        start: {
+          line: 1,
+          offset: 4,
+          column: 5
+        },
+        end: {
+          line: 1,
+          offset: 7,
+          column: 8
         }
-      ] as CompileError[])
-    })
-  }
+      }
+    ],
+    [
+      'aàa',
+      {
+        start: {
+          line: 1,
+          offset: 4,
+          column: 5
+        },
+        end: {
+          line: 1,
+          offset: 7,
+          column: 8
+        }
+      }
+    ]
+  ])(`invalid '%s' in placeholder`, (ch, location) => {
+    parse(`hi {${ch}} !`, options)
+    expect(errors).toEqual([
+      {
+        code: CompileErrorCodes.INVALID_TOKEN_IN_PLACEHOLDER,
+        domain: ERROR_DOMAIN,
+        message: format(
+          errorMessages[CompileErrorCodes.INVALID_TOKEN_IN_PLACEHOLDER],
+          ch
+        ),
+        location
+      }
+    ] as CompileError[])
+  })
 })