Indicate unused variables in high contrast mode

Fixes #51284

Add white underline for unused variable in highcontrast mode

src/vs/editor/browser/widget/codeEditorWidget.ts

@@ -46,7 +46,7 @@ import { IMouseEvent } from 'vs/base/browser/mouseEvent';
 import { InternalEditorAction } from 'vs/editor/common/editorAction';
 import { ICommandDelegate } from 'vs/editor/browser/view/viewController';
 import { CoreEditorCommand } from 'vs/editor/browser/controller/coreCommands';
-import { editorErrorForeground, editorErrorBorder, editorWarningForeground, editorWarningBorder, editorInfoBorder, editorInfoForeground, editorHintForeground, editorHintBorder, editorUnnecessaryCodeOpacity } from 'vs/editor/common/view/editorColorRegistry';
+import { editorErrorForeground, editorErrorBorder, editorWarningForeground, editorWarningBorder, editorInfoBorder, editorInfoForeground, editorHintForeground, editorHintBorder, editorUnnecessaryCodeOpacity, editorUnnecessaryCodeBorder } from 'vs/editor/common/view/editorColorRegistry';
 import { Color } from 'vs/base/common/color';
 import { ClassName } from 'vs/editor/common/model/intervalTree';
 
@@ -1805,6 +1805,11 @@ registerThemingParticipant((theme, collector) => {
 
 	const unnecessaryForeground = theme.getColor(editorUnnecessaryCodeOpacity);
 	if (unnecessaryForeground) {
-		collector.addRule(`.${SHOW_UNUSED_ENABLED_CLASS} .monaco-editor .${ClassName.EditorUnnecessaryDecoration} { opacity: ${unnecessaryForeground.rgba.a}; }`);
+		collector.addRule(`.${SHOW_UNUSED_ENABLED_CLASS} .monaco-editor .${ClassName.EditorUnnecessaryInlineDecoration} { opacity: ${unnecessaryForeground.rgba.a}; }`);
+	}
+
+	const unnecessaryBorder = theme.getColor(editorUnnecessaryCodeBorder);
+	if (unnecessaryBorder) {
+		collector.addRule(`.${SHOW_UNUSED_ENABLED_CLASS} .monaco-editor .${ClassName.EditorUnnecessaryDecoration} { border-bottom: 2px dashed ${unnecessaryBorder}; }`);
 	}
 });

src/vs/editor/common/model/intervalTree.ts

@@ -17,7 +17,8 @@ export const ClassName = {
 	EditorInfoDecoration: 'squiggly-info',
 	EditorWarningDecoration: 'squiggly-warning',
 	EditorErrorDecoration: 'squiggly-error',
-	EditorUnnecessaryDecoration: 'squiggly-overlay-unnecessary'
+	EditorUnnecessaryDecoration: 'squiggly-unnecessary',
+	EditorUnnecessaryInlineDecoration: 'squiggly-inline-unnecessary'
 };
 
 /**

src/vs/editor/common/services/modelServiceImpl.ts

@@ -131,7 +131,9 @@ class ModelMarkerHandler {
 
 		switch (marker.severity) {
 			case MarkerSeverity.Hint:
-				if (!marker.customTags || marker.customTags.indexOf(MarkerTag.Unnecessary) === -1) {
+				if (marker.customTags && marker.customTags.indexOf(MarkerTag.Unnecessary) >= 0) {
+					className = ClassName.EditorUnnecessaryDecoration;
+				} else {
 					className = ClassName.EditorHintDecoration;
 				}
 				zIndex = 0;
@@ -159,7 +161,7 @@ class ModelMarkerHandler {
 
 		if (marker.customTags) {
 			if (marker.customTags.indexOf(MarkerTag.Unnecessary) !== -1) {
-				inlineClassName = ClassName.EditorUnnecessaryDecoration;
+				inlineClassName = ClassName.EditorUnnecessaryInlineDecoration;
 			}
 		}
 

src/vs/editor/common/view/editorColorRegistry.ts

@@ -49,6 +49,7 @@ export const editorInfoBorder = registerColor('editorInfo.border', { dark: null,
 export const editorHintForeground = registerColor('editorHint.foreground', { dark: Color.fromHex('#eeeeee').transparent(0.7), light: '#6c6c6c', hc: null }, nls.localize('hintForeground', 'Foreground color of hint squigglies in the editor.'));
 export const editorHintBorder = registerColor('editorHint.border', { dark: null, light: null, hc: Color.fromHex('#eeeeee').transparent(0.8) }, nls.localize('hintBorder', 'Border color of hint squigglies in the editor.'));
 
+export const editorUnnecessaryCodeBorder = registerColor('editorUnnecessaryCode.border', { dark: null, light: null, hc: Color.fromHex('#fff').transparent(0.8) }, nls.localize('unnecessaryCodeBorder', 'Border of unnecessary code in the editor.'));
 export const editorUnnecessaryCodeOpacity = registerColor('editorUnnecessaryCode.opacity', { dark: Color.fromHex('#0009'), light: Color.fromHex('#0007'), hc: null }, nls.localize('unnecessaryCodeOpacity', 'Opacity of unnecessary code in the editor.'));
 
 const rulerRangeDefault = new Color(new RGBA(0, 122, 204, 0.6));