From be9b79f805a3f738986dd6a2fc9f39e07efe46bf Mon Sep 17 00:00:00 2001
From: Conduitry <git@chor.date>
Date: Mon, 27 Jan 2020 18:25:24 -0500
Subject: [PATCH] fix detection of unused partially global CSS selectors
 (#4332)

---
 CHANGELOG.md                                  |  1 +
 src/compiler/compile/css/Selector.ts          |  2 +-
 .../global-with-unused-descendant/_config.js  | 24 +++++++++++++++++++
 .../expected.css                              |  0
 .../input.svelte                              |  5 ++++
 5 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 test/css/samples/global-with-unused-descendant/_config.js
 create mode 100644 test/css/samples/global-with-unused-descendant/expected.css
 create mode 100644 test/css/samples/global-with-unused-descendant/input.svelte

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 217651e20b..8c68dc1068 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## Unreleased
 
 * Fix code generation error with adjacent inline and block comments ([#4312](https://github.com/sveltejs/svelte/issues/4312))
+* Fix detection of unused CSS selectors that begin with a `:global()` but contain a scoped portion ([#4314](https://github.com/sveltejs/svelte/issues/4314))
 
 ## 3.18.0
 
diff --git a/src/compiler/compile/css/Selector.ts b/src/compiler/compile/css/Selector.ts
index 39bbc2e8d1..6bc046c93e 100644
--- a/src/compiler/compile/css/Selector.ts
+++ b/src/compiler/compile/css/Selector.ts
@@ -32,7 +32,7 @@ export default class Selector {
 		}
 
 		this.local_blocks = this.blocks.slice(0, i);
-		this.used = this.blocks[0].global;
+		this.used = this.local_blocks.length === 0;
 	}
 
 	apply(node: Element, stack: Element[]) {
diff --git a/test/css/samples/global-with-unused-descendant/_config.js b/test/css/samples/global-with-unused-descendant/_config.js
new file mode 100644
index 0000000000..3ed2dd2728
--- /dev/null
+++ b/test/css/samples/global-with-unused-descendant/_config.js
@@ -0,0 +1,24 @@
+export default {
+	warnings: [{
+		code: 'css-unused-selector',
+		end: {
+			character: 27,
+			column: 19,
+			line: 2
+		},
+		frame: `
+			1: <style>
+			2:   :global(.foo) .bar {
+			     ^
+			3:     color: red;
+			4:   }
+		`,
+		message: 'Unused CSS selector',
+		pos: 9,
+		start: {
+			character: 9,
+			column: 1,
+			line: 2
+		}
+	}]
+};
diff --git a/test/css/samples/global-with-unused-descendant/expected.css b/test/css/samples/global-with-unused-descendant/expected.css
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/css/samples/global-with-unused-descendant/input.svelte b/test/css/samples/global-with-unused-descendant/input.svelte
new file mode 100644
index 0000000000..ede6eedec3
--- /dev/null
+++ b/test/css/samples/global-with-unused-descendant/input.svelte
@@ -0,0 +1,5 @@
+<style>
+	:global(.foo) .bar {
+		color: red;
+	}
+</style>