From ce4c4b618330aa5cd2209091de314efa3804f288 Mon Sep 17 00:00:00 2001
From: Alexander T <alexander.tarasyuk@outlook.com>
Date: Sat, 18 Jan 2020 00:24:46 +0200
Subject: [PATCH] fix(36023): fix crash in document highlight service (#36233)

---
 src/services/documentHighlights.ts                  |  8 ++++++--
 .../fourslash/documentHighlightDefaultInKeyword.ts  |  8 ++++++++
 .../fourslash/documentHighlightDefaultInSwitch.ts   | 13 +++++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 tests/cases/fourslash/documentHighlightDefaultInKeyword.ts
 create mode 100644 tests/cases/fourslash/documentHighlightDefaultInSwitch.ts

diff --git a/src/services/documentHighlights.ts b/src/services/documentHighlights.ts
index d3a165f3b8d..37873914411 100644
--- a/src/services/documentHighlights.ts
+++ b/src/services/documentHighlights.ts
@@ -66,8 +66,12 @@ namespace ts {
                 case SyntaxKind.SwitchKeyword:
                     return useParent(node.parent, isSwitchStatement, getSwitchCaseDefaultOccurrences);
                 case SyntaxKind.CaseKeyword:
-                case SyntaxKind.DefaultKeyword:
-                    return useParent(node.parent.parent.parent, isSwitchStatement, getSwitchCaseDefaultOccurrences);
+                case SyntaxKind.DefaultKeyword: {
+                    if (isDefaultClause(node.parent) || isCaseClause(node.parent)) {
+                        return useParent(node.parent.parent.parent, isSwitchStatement, getSwitchCaseDefaultOccurrences);
+                    }
+                    return undefined;
+                }
                 case SyntaxKind.BreakKeyword:
                 case SyntaxKind.ContinueKeyword:
                     return useParent(node.parent, isBreakOrContinueStatement, getBreakOrContinueStatementOccurrences);
diff --git a/tests/cases/fourslash/documentHighlightDefaultInKeyword.ts b/tests/cases/fourslash/documentHighlightDefaultInKeyword.ts
new file mode 100644
index 00000000000..98d45f88ceb
--- /dev/null
+++ b/tests/cases/fourslash/documentHighlightDefaultInKeyword.ts
@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts'/>
+
+////[|case|]
+////[|default|]
+
+const [defaultKeywordRange, caseKeywordRange] = test.ranges();
+verify.noDocumentHighlights(defaultKeywordRange);
+verify.noDocumentHighlights(caseKeywordRange);
diff --git a/tests/cases/fourslash/documentHighlightDefaultInSwitch.ts b/tests/cases/fourslash/documentHighlightDefaultInSwitch.ts
new file mode 100644
index 00000000000..e30366bcf27
--- /dev/null
+++ b/tests/cases/fourslash/documentHighlightDefaultInSwitch.ts
@@ -0,0 +1,13 @@
+/// <reference path='fourslash.ts'/>
+
+////const foo = 'foo';
+////[|switch|] (foo) {
+////   [|case|] 'foo':
+////       [|break|];
+////   [|default|]:
+////       [|break|];
+////}
+
+const [r0, r1, r2, r3, r4] = test.ranges();
+verify.documentHighlightsOf(r1, [r0, r1, r2, r3, r4]);
+verify.documentHighlightsOf(r4, [r0, r1, r2, r3, r4]);