Fix overflow fallback (fixes #415)

Author: lahmatiy

CHANGELOG.md

@@ -2,7 +2,8 @@
 
 - Bumped [CSSTree](https://github.com/csstree/csstree) to `^1.0.0`
 - Fixed wrongly merging of TRBL values when one of them contains `var()` (#420)
-- Fixed wrongly merging of pseudo class and element with the same name, e.g. `:-ms-input-placeholder` and `::-ms-input-placeholder` (#383)
+- Fixed wrongly merging of pseudo class and element with the same name, e.g. `:-ms-input-placeholder` and `::-ms-input-placeholder` (#383, #416)
+- Fixed wrongly merging of `overflow` fallback (#415)
 
 ## 4.0.3 (March 24, 2020)
 

lib/restructure/6-restructBlock.js

@@ -14,17 +14,21 @@ var DONT_MIX_VALUE = {
     'text-align': /^(start|end|match-parent|justify-all)$/i
 };
 
-var CURSOR_SAFE_VALUE = [
-    'auto', 'crosshair', 'default', 'move', 'text', 'wait', 'help',
-    'n-resize', 'e-resize', 's-resize', 'w-resize',
-    'ne-resize', 'nw-resize', 'se-resize', 'sw-resize',
-    'pointer', 'progress', 'not-allowed', 'no-drop', 'vertical-text', 'all-scroll',
-    'col-resize', 'row-resize'
-];
-
-var POSITION_SAFE_VALUE = [
-    'static', 'relative', 'absolute', 'fixed'
-];
+var SAFE_VALUES = {
+    cursor: [
+        'auto', 'crosshair', 'default', 'move', 'text', 'wait', 'help',
+        'n-resize', 'e-resize', 's-resize', 'w-resize',
+        'ne-resize', 'nw-resize', 'se-resize', 'sw-resize',
+        'pointer', 'progress', 'not-allowed', 'no-drop', 'vertical-text', 'all-scroll',
+        'col-resize', 'row-resize'
+    ],
+    overflow: [
+        'hidden', 'visible', 'scroll', 'auto'
+    ],
+    position: [
+        'static', 'relative', 'absolute', 'fixed'
+    ]
+}
 
 var NEEDLESS_TABLE = {
     'border-width': ['border'],
@@ -105,12 +109,8 @@ function getPropertyFingerprint(propertyName, declaration, fingerprints) {
                                 iehack = RegExp.lastMatch;
                             }
 
-                            if (realName === 'cursor') {
-                                if (CURSOR_SAFE_VALUE.indexOf(name) === -1) {
-                                    special[name] = true;
-                                }
-                            } else if (realName === 'position') {
-                                if (POSITION_SAFE_VALUE.indexOf(name) === -1) {
+                            if (SAFE_VALUES.hasOwnProperty(realName)) {
+                                if (SAFE_VALUES[realName].indexOf(name) === -1) {
                                     special[name] = true;
                                 }
                             } else if (DONT_MIX_VALUE.hasOwnProperty(realName)) {

test/fixture/compress/overflow.css

@@ -0,0 +1,5 @@
+/* https://github.com/css/csso/issues/415 */
+.selector {
+    overflow: auto;
+    overflow: overlay;
+}

test/fixture/compress/overflow.min.css

@@ -0,0 +1 @@
+.selector{overflow:auto;overflow:overlay}