From 7465f046666917f224f6435e489afd768fd1fa83 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Tue, 5 Apr 2022 00:05:20 +0300
Subject: [PATCH] fix(48542): omit parameter info of contextual union type
 (#48549)

---
 src/services/signatureHelp.ts                 |   9 +-
 .../signatureHelp_unionType.baseline          | 419 ++++++++++++++++++
 .../fourslash/signatureHelp_unionType.ts      |  21 +
 3 files changed, 446 insertions(+), 3 deletions(-)
 create mode 100644 tests/baselines/reference/signatureHelp_unionType.baseline
 create mode 100644 tests/cases/fourslash/signatureHelp_unionType.ts

diff --git a/src/services/signatureHelp.ts b/src/services/signatureHelp.ts
index e26b0f49425..eefc1c44e9c 100644
--- a/src/services/signatureHelp.ts
+++ b/src/services/signatureHelp.ts
@@ -307,10 +307,13 @@ namespace ts.SignatureHelp {
         // for optional function condition.
         const nonNullableContextualType = contextualType.getNonNullableType();
 
-        const signatures = nonNullableContextualType.getCallSignatures();
-        if (signatures.length !== 1) return undefined;
+        const symbol = nonNullableContextualType.symbol;
+        if (symbol === undefined) return undefined;
 
-        const invocation: ContextualInvocation = { kind: InvocationKind.Contextual, signature: first(signatures), node: startingToken, symbol: chooseBetterSymbol(nonNullableContextualType.symbol) };
+        const signature = lastOrUndefined(nonNullableContextualType.getCallSignatures());
+        if (signature === undefined) return undefined;
+
+        const invocation: ContextualInvocation = { kind: InvocationKind.Contextual, signature, node: startingToken, symbol: chooseBetterSymbol(symbol) };
         return { isTypeParameterList: false, invocation, argumentsSpan, argumentIndex, argumentCount };
     }
 
diff --git a/tests/baselines/reference/signatureHelp_unionType.baseline b/tests/baselines/reference/signatureHelp_unionType.baseline
new file mode 100644
index 00000000000..17ba6f279be
--- /dev/null
+++ b/tests/baselines/reference/signatureHelp_unionType.baseline
@@ -0,0 +1,419 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/signatureHelp_unionType.ts",
+      "position": 296,
+      "name": "1"
+    },
+    "signatureHelp": {
+      "items": [
+        {
+          "isVariadic": false,
+          "prefixDisplayParts": [
+            {
+              "text": "a",
+              "kind": "localName"
+            },
+            {
+              "text": "(",
+              "kind": "punctuation"
+            }
+          ],
+          "suffixDisplayParts": [
+            {
+              "text": ")",
+              "kind": "punctuation"
+            },
+            {
+              "text": ":",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            },
+            {
+              "text": "void",
+              "kind": "keyword"
+            }
+          ],
+          "separatorDisplayParts": [
+            {
+              "text": ",",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            }
+          ],
+          "parameters": [
+            {
+              "name": "fn",
+              "documentation": [],
+              "displayParts": [
+                {
+                  "text": "fn",
+                  "kind": "parameterName"
+                },
+                {
+                  "text": "?",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": ":",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "(",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": "(",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": "x",
+                  "kind": "parameterName"
+                },
+                {
+                  "text": ":",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "string",
+                  "kind": "keyword"
+                },
+                {
+                  "text": ")",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "=>",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "string",
+                  "kind": "keyword"
+                },
+                {
+                  "text": ")",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "|",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "(",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": "(",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": "y",
+                  "kind": "parameterName"
+                },
+                {
+                  "text": ":",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "number",
+                  "kind": "keyword"
+                },
+                {
+                  "text": ")",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "=>",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "number",
+                  "kind": "keyword"
+                },
+                {
+                  "text": ")",
+                  "kind": "punctuation"
+                }
+              ],
+              "isOptional": true,
+              "isRest": false
+            }
+          ],
+          "documentation": [],
+          "tags": []
+        }
+      ],
+      "applicableSpan": {
+        "start": 295,
+        "length": 31
+      },
+      "selectedItemIndex": 0,
+      "argumentIndex": 0,
+      "argumentCount": 1
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/signatureHelp_unionType.ts",
+      "position": 332,
+      "name": "2"
+    },
+    "signatureHelp": {
+      "items": [
+        {
+          "isVariadic": false,
+          "prefixDisplayParts": [
+            {
+              "text": "b",
+              "kind": "localName"
+            },
+            {
+              "text": "(",
+              "kind": "punctuation"
+            }
+          ],
+          "suffixDisplayParts": [
+            {
+              "text": ")",
+              "kind": "punctuation"
+            },
+            {
+              "text": ":",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            },
+            {
+              "text": "void",
+              "kind": "keyword"
+            }
+          ],
+          "separatorDisplayParts": [
+            {
+              "text": ",",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            }
+          ],
+          "parameters": [
+            {
+              "name": "x",
+              "documentation": [],
+              "displayParts": [
+                {
+                  "text": "x",
+                  "kind": "parameterName"
+                },
+                {
+                  "text": ":",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "string",
+                  "kind": "keyword"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "|",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "number",
+                  "kind": "keyword"
+                }
+              ],
+              "isOptional": false,
+              "isRest": false
+            }
+          ],
+          "documentation": [],
+          "tags": []
+        }
+      ],
+      "applicableSpan": {
+        "start": 332,
+        "length": 0
+      },
+      "selectedItemIndex": 0,
+      "argumentIndex": 0,
+      "argumentCount": 0
+    }
+  },
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/signatureHelp_unionType.ts",
+      "position": 339,
+      "name": "3"
+    },
+    "signatureHelp": {
+      "items": [
+        {
+          "isVariadic": false,
+          "prefixDisplayParts": [
+            {
+              "text": "Callback",
+              "kind": "interfaceName"
+            },
+            {
+              "text": "(",
+              "kind": "punctuation"
+            }
+          ],
+          "suffixDisplayParts": [
+            {
+              "text": ")",
+              "kind": "punctuation"
+            },
+            {
+              "text": ":",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            },
+            {
+              "text": "string",
+              "kind": "keyword"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            },
+            {
+              "text": "|",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            },
+            {
+              "text": "number",
+              "kind": "keyword"
+            }
+          ],
+          "separatorDisplayParts": [
+            {
+              "text": ",",
+              "kind": "punctuation"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            }
+          ],
+          "parameters": [
+            {
+              "name": "x",
+              "documentation": [],
+              "displayParts": [
+                {
+                  "text": "x",
+                  "kind": "parameterName"
+                },
+                {
+                  "text": ":",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "string",
+                  "kind": "keyword"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "|",
+                  "kind": "punctuation"
+                },
+                {
+                  "text": " ",
+                  "kind": "space"
+                },
+                {
+                  "text": "number",
+                  "kind": "keyword"
+                }
+              ],
+              "isOptional": false,
+              "isRest": false
+            }
+          ],
+          "documentation": [],
+          "tags": []
+        }
+      ],
+      "applicableSpan": {
+        "start": 339,
+        "length": 0
+      },
+      "selectedItemIndex": 0,
+      "argumentIndex": 0,
+      "argumentCount": 0
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/cases/fourslash/signatureHelp_unionType.ts b/tests/cases/fourslash/signatureHelp_unionType.ts
new file mode 100644
index 00000000000..0548ac1e689
--- /dev/null
+++ b/tests/cases/fourslash/signatureHelp_unionType.ts
@@ -0,0 +1,21 @@
+/// <reference path="fourslash.ts" />
+
+////declare const a: (fn?: ((x: string) => string) | ((y: number) => number)) => void;
+////declare const b: (x: string | number) => void;
+////
+////interface Callback {
+////    (x: string): string;
+////    (x: number): number;
+////    (x: string | number): string | number;
+////}
+////declare function c(callback: Callback): void;
+
+////a((/*1*/) => {
+////    return undefined;
+////});
+////
+////b(/*2*/);
+////
+////c((/*3*/) => {});
+
+verify.baselineSignatureHelp();