From 5adb55eb1815db7b2b2dd98374848886a3c7d16f Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Wed, 25 Nov 2020 00:40:51 +0200
Subject: [PATCH] feat(41216): show JSDoc for aliases (#41452)

---
 src/services/symbolDisplay.ts                 |   4 +
 .../reference/jsDocAliasQuickInfo.baseline    | 162 ++++++++++++++++++
 tests/cases/fourslash/jsDocAliasQuickInfo.ts  |  13 ++
 3 files changed, 179 insertions(+)
 create mode 100644 tests/baselines/reference/jsDocAliasQuickInfo.baseline
 create mode 100644 tests/cases/fourslash/jsDocAliasQuickInfo.ts

diff --git a/src/services/symbolDisplay.ts b/src/services/symbolDisplay.ts
index 6813ad3f9bc..2a2a1f846d5 100644
--- a/src/services/symbolDisplay.ts
+++ b/src/services/symbolDisplay.ts
@@ -422,6 +422,10 @@ namespace ts.SymbolDisplay {
                         documentationFromAlias = resolvedInfo.documentation;
                         tagsFromAlias = resolvedInfo.tags;
                     }
+                    else {
+                        documentationFromAlias = resolvedSymbol.getContextualDocumentationComment(resolvedNode, typeChecker);
+                        tagsFromAlias = resolvedSymbol.getJsDocTags();
+                    }
                 }
             }
 
diff --git a/tests/baselines/reference/jsDocAliasQuickInfo.baseline b/tests/baselines/reference/jsDocAliasQuickInfo.baseline
new file mode 100644
index 00000000000..07bb13ae351
--- /dev/null
+++ b/tests/baselines/reference/jsDocAliasQuickInfo.baseline
@@ -0,0 +1,162 @@
+[
+  {
+    "marker": {
+      "fileName": "/jsDocAliasQuickInfo.ts",
+      "position": 44
+    },
+    "quickInfo": {
+      "kind": "property",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 44,
+        "length": 7
+      },
+      "displayParts": [
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "property",
+          "kind": "text"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "default",
+          "kind": "propertyName"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "10",
+          "kind": "stringLiteral"
+        }
+      ],
+      "documentation": [
+        {
+          "text": "Comment",
+          "kind": "text"
+        }
+      ],
+      "tags": [
+        {
+          "name": "type",
+          "text": "{number}"
+        }
+      ]
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/test.ts",
+      "position": 9
+    },
+    "quickInfo": {
+      "kind": "property",
+      "kindModifiers": "export",
+      "textSpan": {
+        "start": 9,
+        "length": 7
+      },
+      "displayParts": [
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "property",
+          "kind": "text"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "default",
+          "kind": "propertyName"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "10",
+          "kind": "stringLiteral"
+        }
+      ],
+      "documentation": [
+        {
+          "text": "Comment",
+          "kind": "text"
+        }
+      ],
+      "tags": [
+        {
+          "name": "type",
+          "text": "{number}"
+        }
+      ]
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/test.ts",
+      "position": 20
+    },
+    "quickInfo": {
+      "kind": "alias",
+      "kindModifiers": "",
+      "textSpan": {
+        "start": 20,
+        "length": 4
+      },
+      "displayParts": [
+        {
+          "text": "export",
+          "kind": "keyword"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "test",
+          "kind": "aliasName"
+        }
+      ],
+      "documentation": [
+        {
+          "text": "Comment",
+          "kind": "text"
+        }
+      ],
+      "tags": [
+        {
+          "name": "type",
+          "text": "{number}"
+        }
+      ]
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/cases/fourslash/jsDocAliasQuickInfo.ts b/tests/cases/fourslash/jsDocAliasQuickInfo.ts
new file mode 100644
index 00000000000..e5b74a81d53
--- /dev/null
+++ b/tests/cases/fourslash/jsDocAliasQuickInfo.ts
@@ -0,0 +1,13 @@
+/// <reference path='fourslash.ts'/>
+
+// @Filename: /jsDocAliasQuickInfo.ts
+/////**
+//// * Comment
+//// * @type {number}
+//// */
+////export /*1*/default 10;
+
+// @Filename: /test.ts
+////export { /*2*/default as /*3*/test } from "./jsDocAliasQuickInfo";
+
+verify.baselineQuickInfo();