fix: report precise error line numbers in --show-errors (#51)

* chore(deps): add minimatch as direct dependency

minimatch was being imported directly but only available as a transitive
dependency through glob. This caused build failures with pnpm's strict
dependency resolution.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix: report precise error line numbers in --show-errors

Previously, --show-errors reported the line number where the function
starts (event.fnLoc) rather than the exact line where the React compiler
violation occurs.

Now uses:
- event.detail.primaryLocation() for CompileError events
- event.loc for CompileSkip events

This provides users with accurate line numbers pointing to the exact
location of violations, making it easier to find and fix issues.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: frankieyan

package.json

@@ -67,6 +67,7 @@
     "@babel/core": "7.28.6",
     "@babel/preset-react": "7.28.5",
     "@babel/preset-typescript": "7.28.5",
-    "glob": "13.0.0"
+    "glob": "13.0.0",
+    "minimatch": "10.1.1"
   }
 }

src/index.integration.test.mts

@@ -47,7 +47,13 @@ describe('CLI', () => {
 
             expect(output).toContain('Found 4 React Compiler issues')
             expect(output).toContain('Errors:')
-            expect(output).toMatch(/Line \d+:/)
+            expect(output).toContain(
+                'src/bad-hook.ts: Line 9: Cannot access refs during render (x2)',
+            )
+            expect(output).toContain('src/bad-hook.ts: Line 10: Cannot access refs during render')
+            expect(output).toContain(
+                'src/bad-component.tsx: Line 9: Hooks must always be called in a consistent order',
+            )
         })
     })
 
@@ -85,8 +91,9 @@ describe('CLI', () => {
             expect(output).toContain('React Compiler errors have increased')
             expect(output).toContain('Errors:')
             expect(output).toContain(
-                'src/bad-hook.ts: Line 6: Cannot access refs during render (x3)',
+                'src/bad-hook.ts: Line 9: Cannot access refs during render (x2)',
             )
+            expect(output).toContain('src/bad-hook.ts: Line 10: Cannot access refs during render')
         })
 
         it('--show-errors shows errors even when no increase', () => {
@@ -95,8 +102,9 @@ describe('CLI', () => {
 
             expect(output).toContain('Errors:')
             expect(output).toContain(
-                'src/bad-hook.ts: Line 6: Cannot access refs during render (x3)',
+                'src/bad-hook.ts: Line 9: Cannot access refs during render (x2)',
             )
+            expect(output).toContain('src/bad-hook.ts: Line 10: Cannot access refs during render')
             expect(output).not.toContain('React Compiler errors have increased')
             expect(output).toContain('✅ No new React Compiler errors')
         })
@@ -131,7 +139,13 @@ describe('CLI', () => {
 
             expect(output).toContain('Records saved to')
             expect(output).toContain('Errors:')
-            expect(output).toMatch(/Line \d+:/)
+            expect(output).toContain(
+                'src/bad-hook.ts: Line 9: Cannot access refs during render (x2)',
+            )
+            expect(output).toContain('src/bad-hook.ts: Line 10: Cannot access refs during render')
+            expect(output).toContain(
+                'src/bad-component.tsx: Line 9: Hooks must always be called in a consistent order',
+            )
         })
     })
 
@@ -162,7 +176,10 @@ describe('CLI', () => {
 
             expect(output).toContain('React Compiler errors have increased')
             expect(output).toContain('Errors:')
-            expect(output).toMatch(/Line \d+:/)
+            expect(output).toContain(
+                'src/bad-hook.ts: Line 9: Cannot access refs during render (x2)',
+            )
+            expect(output).toContain('src/bad-hook.ts: Line 10: Cannot access refs during render')
         })
 
         it('--stage-record-file --show-errors shows errors even when no increase', () => {
@@ -171,8 +188,9 @@ describe('CLI', () => {
 
             expect(output).toContain('Errors:')
             expect(output).toContain(
-                'src/bad-hook.ts: Line 6: Cannot access refs during render (x3)',
+                'src/bad-hook.ts: Line 9: Cannot access refs during render (x2)',
             )
+            expect(output).toContain('src/bad-hook.ts: Line 10: Cannot access refs during render')
             expect(output).not.toContain('React Compiler errors have increased')
         })
 

src/index.mts

@@ -36,13 +36,25 @@ const customReactCompilerLogger: ReactCompilerLogger = {
             current[event.kind] = (current[event.kind] ?? 0) + 1
             compilerErrors.set(relativePath, current)
 
-            const line = event.fnLoc?.start.line ?? null
+            let line: number | null
             let reason: string
+
             if (event.kind === 'CompileError') {
+                // Use primaryLocation() for precise error location, fall back to fnLoc
+                // primaryLocation() may return a symbol (GeneratedSource), so check for object
+                const loc = event.detail.primaryLocation()
+                line =
+                    (loc && typeof loc === 'object' ? loc.start.line : null) ??
+                    event.fnLoc?.start.line ??
+                    null
                 reason = event.detail.reason
             } else if (event.kind === 'CompileSkip') {
+                // CompileSkip has its own loc field for the precise location
+                line = event.loc?.start.line ?? event.fnLoc?.start.line ?? null
                 reason = event.reason
             } else {
+                // PipelineError only has fnLoc
+                line = event.fnLoc?.start.line ?? null
                 reason = String(event.data)
             }