From 6734eeb74b1e76cbd93875bdaf8c99b848f8ae0a Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Sun, 5 Sep 2021 10:03:09 +0300
Subject: [PATCH] fix(45692): merge non-primitive in spread-union

---
 src/compiler/checker.ts                       |  2 +-
 tests/baselines/reference/spreadUnion4.js     | 20 +++++++++++++++++++
 .../baselines/reference/spreadUnion4.symbols  | 14 +++++++++++++
 tests/baselines/reference/spreadUnion4.types  | 15 ++++++++++++++
 .../conformance/types/spread/spreadUnion4.ts  |  4 ++++
 5 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/spreadUnion4.js
 create mode 100644 tests/baselines/reference/spreadUnion4.symbols
 create mode 100644 tests/baselines/reference/spreadUnion4.types
 create mode 100644 tests/cases/conformance/types/spread/spreadUnion4.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 186422e5a90c0..8522a0605abe7 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15600,7 +15600,7 @@ namespace ts {
                         const declarations = concatenate(leftProp.declarations, rightProp.declarations);
                         const flags = SymbolFlags.Property | (leftProp.flags & SymbolFlags.Optional);
                         const result = createSymbol(flags, leftProp.escapedName);
-                        result.type = getUnionType([getTypeOfSymbol(leftProp), removeMissingOrUndefinedType(rightType)]);
+                        result.type = getUnionType([getTypeOfSymbol(leftProp), removeMissingOrUndefinedType(rightType)], UnionReduction.Subtype);
                         result.leftSpread = leftProp;
                         result.rightSpread = rightProp;
                         result.declarations = declarations;
diff --git a/tests/baselines/reference/spreadUnion4.js b/tests/baselines/reference/spreadUnion4.js
new file mode 100644
index 0000000000000..9887c8e6f1794
--- /dev/null
+++ b/tests/baselines/reference/spreadUnion4.js
@@ -0,0 +1,20 @@
+//// [spreadUnion4.ts]
+declare const a: { x: () => void }
+declare const b: { x?: () => void }
+
+const c = { ...a, ...b };
+
+
+//// [spreadUnion4.js]
+var __assign = (this && this.__assign) || function () {
+    __assign = Object.assign || function(t) {
+        for (var s, i = 1, n = arguments.length; i < n; i++) {
+            s = arguments[i];
+            for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+                t[p] = s[p];
+        }
+        return t;
+    };
+    return __assign.apply(this, arguments);
+};
+var c = __assign(__assign({}, a), b);
diff --git a/tests/baselines/reference/spreadUnion4.symbols b/tests/baselines/reference/spreadUnion4.symbols
new file mode 100644
index 0000000000000..85f9071e31d9b
--- /dev/null
+++ b/tests/baselines/reference/spreadUnion4.symbols
@@ -0,0 +1,14 @@
+=== tests/cases/conformance/types/spread/spreadUnion4.ts ===
+declare const a: { x: () => void }
+>a : Symbol(a, Decl(spreadUnion4.ts, 0, 13))
+>x : Symbol(x, Decl(spreadUnion4.ts, 0, 18))
+
+declare const b: { x?: () => void }
+>b : Symbol(b, Decl(spreadUnion4.ts, 1, 13))
+>x : Symbol(x, Decl(spreadUnion4.ts, 1, 18))
+
+const c = { ...a, ...b };
+>c : Symbol(c, Decl(spreadUnion4.ts, 3, 5))
+>a : Symbol(a, Decl(spreadUnion4.ts, 0, 13))
+>b : Symbol(b, Decl(spreadUnion4.ts, 1, 13))
+
diff --git a/tests/baselines/reference/spreadUnion4.types b/tests/baselines/reference/spreadUnion4.types
new file mode 100644
index 0000000000000..d3be34c89c70f
--- /dev/null
+++ b/tests/baselines/reference/spreadUnion4.types
@@ -0,0 +1,15 @@
+=== tests/cases/conformance/types/spread/spreadUnion4.ts ===
+declare const a: { x: () => void }
+>a : { x: () => void; }
+>x : () => void
+
+declare const b: { x?: () => void }
+>b : { x?: () => void; }
+>x : () => void
+
+const c = { ...a, ...b };
+>c : { x: () => void; }
+>{ ...a, ...b } : { x: () => void; }
+>a : { x: () => void; }
+>b : { x?: () => void; }
+
diff --git a/tests/cases/conformance/types/spread/spreadUnion4.ts b/tests/cases/conformance/types/spread/spreadUnion4.ts
new file mode 100644
index 0000000000000..6a39ac3a3cc40
--- /dev/null
+++ b/tests/cases/conformance/types/spread/spreadUnion4.ts
@@ -0,0 +1,4 @@
+declare const a: { x: () => void }
+declare const b: { x?: () => void }
+
+const c = { ...a, ...b };