From 04e9b99b09eb9f7d3cd19f143a983056faba0054 Mon Sep 17 00:00:00 2001
From: ConnorSkees <39542938+ConnorSkees@users.noreply.github.com>
Date: Fri, 3 Apr 2020 16:38:01 -0400
Subject: [PATCH] fail on duplicate key in map declaration

---
 src/value/map.rs   | 8 +++++---
 src/value/parse.rs | 4 +++-
 tests/map.rs       | 4 ++++
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/value/map.rs b/src/value/map.rs
index c2e9d78..78e3308 100644
--- a/src/value/map.rs
+++ b/src/value/map.rs
@@ -56,14 +56,16 @@ impl SassMap {
             .collect()
     }
 
-    pub fn insert(&mut self, key: Value, value: Value) {
-        for &mut (ref k, ref mut v) in &mut self.0 {
+    /// Returns true if the key already exists
+    pub fn insert(&mut self, key: Value, value: Value) -> bool {
+        for (ref k, ref mut v) in &mut self.0 {
             if k == &key {
                 *v = value;
-                return;
+                return true;
             }
         }
         self.0.push((key, value));
+        false
     }
 }
 
diff --git a/src/value/parse.rs b/src/value/parse.rs
index c604dc8..4d95018 100644
--- a/src/value/parse.rs
+++ b/src/value/parse.rs
@@ -325,7 +325,9 @@ impl Value {
                             super_selector,
                         )?;
                         devour_whitespace(paren_toks);
-                        map.insert(key, val);
+                        if map.insert(key, val) {
+                            return Err("Duplicate key.".into());
+                        }
                         if paren_toks.peek().is_none() {
                             break;
                         }
diff --git a/tests/map.rs b/tests/map.rs
index 4e6efa3..baba436 100644
--- a/tests/map.rs
+++ b/tests/map.rs
@@ -129,3 +129,7 @@ test!(
     "a {\n  color: inspect(map-remove((\"foo\": 1, \"bar\": 2, \"baz\": 3), \"bar\", \"baz\"));\n}\n",
     "a {\n  color: (\"foo\": 1);\n}\n"
 );
+error!(
+    duplicate_key_in_declaration,
+    "a {\n  $a: (foo: a, foo: b);;\n}\n", "Error: Duplicate key."
+);