From 31f511aae738449cc1a2f0f71d98230f05204a21 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Tue, 5 Jun 2018 14:27:29 -0700
Subject: [PATCH] Don't boost tree-sitter grammars' score unless they match in
 some way

---
 spec/grammar-registry-spec.js | 8 ++++++++
 src/grammar-registry.js       | 8 +++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/spec/grammar-registry-spec.js b/spec/grammar-registry-spec.js
index dbcd03e93..85b5ba8ee 100644
--- a/spec/grammar-registry-spec.js
+++ b/spec/grammar-registry-spec.js
@@ -415,6 +415,14 @@ describe('GrammarRegistry', () => {
         expect(grammar.id).toBe('javascript')
         expect(grammar instanceof TreeSitterGrammar).toBe(true)
       })
+
+      it('only favors a tree-sitter grammar if it actually matches in some way (regression)', () => {
+        atom.config.set('core.useTreeSitterParsers', true)
+        grammarRegistry.loadGrammarSync(require.resolve('language-javascript/grammars/tree-sitter-javascript.cson'))
+
+        const grammar = grammarRegistry.selectGrammar('test', '')
+        expect(grammar.name).toBe('Null Grammar')
+      })
     })
 
     describe('tree-sitter grammars with content regexes', () => {
diff --git a/src/grammar-registry.js b/src/grammar-registry.js
index d494d4f55..e92091286 100644
--- a/src/grammar-registry.js
+++ b/src/grammar-registry.js
@@ -214,11 +214,7 @@ class GrammarRegistry {
     }
 
     if (grammar instanceof TreeSitterGrammar) {
-      if (this.config.get('core.useTreeSitterParsers')) {
-        score += 0.05
-      } else {
-        score = -Infinity
-      }
+      if (!this.config.get('core.useTreeSitterParsers')) return -Infinity
 
       if (grammar.contentRegExp) {
         if (grammar.contentRegExp.test(contents)) {
@@ -227,6 +223,8 @@ class GrammarRegistry {
           score -= 0.25
         }
       }
+
+      if (score > 0) score += 0.05
     } else if (this.grammarMatchesPrefix(grammar, contents)) {
       score += 0.25
     }