Merge pull request #2516 from code-yeongyu/fix/hashline-strict-whitespace-hash

fix(hashline): use strict whitespace hashing (trimEnd only, preserve leading indentation)

src/tools/hashline-edit/hash-computation.test.ts

@@ -45,10 +45,36 @@ describe("computeLineHash", () => {
     expect(hash1).not.toBe(hash2)
   })
 
-  it("ignores whitespace differences", () => {
+  it("produces different hashes for different leading indentation", () => {
     //#given
     const content1 = "function hello() {"
-    const content2 = "  function hello() {  "
+    const content2 = "  function hello() {"
+
+    //#when
+    const hash1 = computeLineHash(1, content1)
+    const hash2 = computeLineHash(1, content2)
+
+    //#then
+    expect(hash1).not.toBe(hash2)
+  })
+
+  it("ignores trailing whitespace differences", () => {
+    //#given
+    const content1 = "function hello() {"
+    const content2 = "function hello() {  "
+
+    //#when
+    const hash1 = computeLineHash(1, content1)
+    const hash2 = computeLineHash(1, content2)
+
+    //#then
+    expect(hash1).toBe(hash2)
+  })
+
+  it("produces same hash for CRLF and LF line endings", () => {
+    //#given
+    const content1 = "function hello() {"
+    const content2 = "function hello() {\r"
 
     //#when
     const hash1 = computeLineHash(1, content1)

src/tools/hashline-edit/hash-computation.ts

@@ -4,7 +4,7 @@ import { createHashlineChunkFormatter } from "./hashline-chunk-formatter"
 const RE_SIGNIFICANT = /[\p{L}\p{N}]/u
 
 export function computeLineHash(lineNumber: number, content: string): string {
-  const stripped = content.endsWith("\r") ? content.slice(0, -1).replace(/\s+/g, "") : content.replace(/\s+/g, "")
+  const stripped = content.replace(/\r/g, "").trimEnd()
   const seed = RE_SIGNIFICANT.test(stripped) ? 0 : lineNumber
   const hash = Bun.hash.xxHash32(stripped, seed)
   const index = hash % 256