From ee0b57867f04ee0454fbb347cbc600ebf12740ca Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Mon, 18 Jul 2022 15:51:37 -0700
Subject: [PATCH 1/3] Don't leak EvolvingArray out of code flow

---
 src/compiler/checker.ts                       |   8 +-
 .../quickInfoEvolvingArrayType.baseline       | 108 ++++++++++++++++++
 .../fourslash/quickInfoEvolvingArrayType.ts   |  15 +++
 3 files changed, 130 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/quickInfoEvolvingArrayType.baseline
 create mode 100644 tests/cases/fourslash/quickInfoEvolvingArrayType.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ce644034b9c3b..82d1ab321f2b9 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11896,6 +11896,9 @@ namespace ts {
                     else if ((type as MappedType).objectFlags & ObjectFlags.Mapped) {
                         resolveMappedTypeMembers(type as MappedType);
                     }
+                    else {
+                        Debug.fail("Unhandled object type " + Debug.formatObjectFlags(type.objectFlags));
+                    }
                 }
                 else if (type.flags & TypeFlags.Union) {
                     resolveUnionTypeMembers(type as UnionType);
@@ -11903,6 +11906,9 @@ namespace ts {
                 else if (type.flags & TypeFlags.Intersection) {
                     resolveIntersectionTypeMembers(type as IntersectionType);
                 }
+                else {
+                    Debug.fail("Unhandled type " + Debug.formatTypeFlags(type.flags));
+                }
             }
             return type as ResolvedType;
         }
@@ -24613,7 +24619,7 @@ namespace ts {
                 }
                 // for (const _ in ref) acts as a nonnull on ref
                 if (isVariableDeclaration(node) && node.parent.parent.kind === SyntaxKind.ForInStatement && isMatchingReference(reference, node.parent.parent.expression)) {
-                    return getNonNullableTypeIfNeeded(getTypeFromFlowType(getTypeAtFlowNode(flow.antecedent)));
+                    return getNonNullableTypeIfNeeded(finalizeEvolvingArrayType(getTypeFromFlowType(getTypeAtFlowNode(flow.antecedent))));
                 }
                 // Assignment doesn't affect reference
                 return undefined;
diff --git a/tests/baselines/reference/quickInfoEvolvingArrayType.baseline b/tests/baselines/reference/quickInfoEvolvingArrayType.baseline
new file mode 100644
index 0000000000000..3171d065aa957
--- /dev/null
+++ b/tests/baselines/reference/quickInfoEvolvingArrayType.baseline
@@ -0,0 +1,108 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/quickInfoEvolvingArrayType.ts",
+      "position": 45,
+      "name": "1"
+    },
+    "quickInfo": {
+      "kind": "method",
+      "kindModifiers": "declare",
+      "textSpan": {
+        "start": 39,
+        "length": 14
+      },
+      "displayParts": [
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "method",
+          "kind": "text"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "Object",
+          "kind": "localName"
+        },
+        {
+          "text": ".",
+          "kind": "punctuation"
+        },
+        {
+          "text": "hasOwnProperty",
+          "kind": "methodName"
+        },
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "v",
+          "kind": "parameterName"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "PropertyKey",
+          "kind": "aliasName"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "boolean",
+          "kind": "keyword"
+        }
+      ],
+      "documentation": [
+        {
+          "text": "Determines whether an object has a property with the specified name.",
+          "kind": "text"
+        }
+      ],
+      "tags": [
+        {
+          "name": "param",
+          "text": [
+            {
+              "text": "v",
+              "kind": "parameterName"
+            },
+            {
+              "text": " ",
+              "kind": "space"
+            },
+            {
+              "text": "A property name.",
+              "kind": "text"
+            }
+          ]
+        }
+      ]
+    }
+  }
+]
\ No newline at end of file
diff --git a/tests/cases/fourslash/quickInfoEvolvingArrayType.ts b/tests/cases/fourslash/quickInfoEvolvingArrayType.ts
new file mode 100644
index 0000000000000..c16d905b4a0a5
--- /dev/null
+++ b/tests/cases/fourslash/quickInfoEvolvingArrayType.ts
@@ -0,0 +1,15 @@
+///<reference path="fourslash.ts" />
+
+// @strict: true
+// @checkJs: true
+// @allowJs: true
+// @outDir: ./dist
+
+// filename: index.js
+//// var C = [];
+//// for (var a in C)
+////     if (C.hasOwn/*1*/Property(a)) {
+////     }
+//// }
+
+verify.baselineQuickInfo();

From 9a5ef9b8d93fe4910a5cc75cc17a2a4279f3c6e9 Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Mon, 18 Jul 2022 16:34:25 -0700
Subject: [PATCH 2/3] Switch to compiler test

---
 .../evolvingArrayResolvedAssert.errors.txt    |  18 +++
 .../reference/evolvingArrayResolvedAssert.js  |  15 +++
 .../evolvingArrayResolvedAssert.symbols       |  16 +++
 .../evolvingArrayResolvedAssert.types         |  18 +++
 .../quickInfoEvolvingArrayType.baseline       | 108 ------------------
 .../compiler/evolvingArrayResolvedAssert.ts   |  11 ++
 .../fourslash/quickInfoEvolvingArrayType.ts   |  15 ---
 7 files changed, 78 insertions(+), 123 deletions(-)
 create mode 100644 tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt
 create mode 100644 tests/baselines/reference/evolvingArrayResolvedAssert.js
 create mode 100644 tests/baselines/reference/evolvingArrayResolvedAssert.symbols
 create mode 100644 tests/baselines/reference/evolvingArrayResolvedAssert.types
 delete mode 100644 tests/baselines/reference/quickInfoEvolvingArrayType.baseline
 create mode 100644 tests/cases/compiler/evolvingArrayResolvedAssert.ts
 delete mode 100644 tests/cases/fourslash/quickInfoEvolvingArrayType.ts

diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt b/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt
new file mode 100644
index 0000000000000..9c21c78820279
--- /dev/null
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt
@@ -0,0 +1,18 @@
+tests/cases/compiler/index.js(1,5): error TS7034: Variable 'C' implicitly has type 'any[]' in some locations where its type cannot be determined.
+tests/cases/compiler/index.js(2,15): error TS7005: Variable 'C' implicitly has an 'any[]' type.
+tests/cases/compiler/index.js(3,9): error TS7005: Variable 'C' implicitly has an 'any[]' type.
+
+
+==== tests/cases/compiler/index.js (3 errors) ====
+    var C = [];
+        ~
+!!! error TS7034: Variable 'C' implicitly has type 'any[]' in some locations where its type cannot be determined.
+    for (var a in C) {
+                  ~
+!!! error TS7005: Variable 'C' implicitly has an 'any[]' type.
+        if (C.hasOwnProperty(a)) {
+            ~
+!!! error TS7005: Variable 'C' implicitly has an 'any[]' type.
+        }
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.js b/tests/baselines/reference/evolvingArrayResolvedAssert.js
new file mode 100644
index 0000000000000..0ffb6e71de6b9
--- /dev/null
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.js
@@ -0,0 +1,15 @@
+//// [index.js]
+var C = [];
+for (var a in C) {
+    if (C.hasOwnProperty(a)) {
+    }
+}
+
+
+//// [index.js]
+"use strict";
+var C = [];
+for (var a in C) {
+    if (C.hasOwnProperty(a)) {
+    }
+}
diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.symbols b/tests/baselines/reference/evolvingArrayResolvedAssert.symbols
new file mode 100644
index 0000000000000..8afcfab09152c
--- /dev/null
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.symbols
@@ -0,0 +1,16 @@
+=== tests/cases/compiler/index.js ===
+var C = [];
+>C : Symbol(C, Decl(index.js, 0, 3))
+
+for (var a in C) {
+>a : Symbol(a, Decl(index.js, 1, 8))
+>C : Symbol(C, Decl(index.js, 0, 3))
+
+    if (C.hasOwnProperty(a)) {
+>C.hasOwnProperty : Symbol(Object.hasOwnProperty, Decl(lib.es5.d.ts, --, --))
+>C : Symbol(C, Decl(index.js, 0, 3))
+>hasOwnProperty : Symbol(Object.hasOwnProperty, Decl(lib.es5.d.ts, --, --))
+>a : Symbol(a, Decl(index.js, 1, 8))
+    }
+}
+
diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.types b/tests/baselines/reference/evolvingArrayResolvedAssert.types
new file mode 100644
index 0000000000000..91e5d706fb29c
--- /dev/null
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.types
@@ -0,0 +1,18 @@
+=== tests/cases/compiler/index.js ===
+var C = [];
+>C : any[]
+>[] : never[]
+
+for (var a in C) {
+>a : string
+>C : any[]
+
+    if (C.hasOwnProperty(a)) {
+>C.hasOwnProperty(a) : boolean
+>C.hasOwnProperty : (v: PropertyKey) => boolean
+>C : any[]
+>hasOwnProperty : (v: PropertyKey) => boolean
+>a : string
+    }
+}
+
diff --git a/tests/baselines/reference/quickInfoEvolvingArrayType.baseline b/tests/baselines/reference/quickInfoEvolvingArrayType.baseline
deleted file mode 100644
index 3171d065aa957..0000000000000
--- a/tests/baselines/reference/quickInfoEvolvingArrayType.baseline
+++ /dev/null
@@ -1,108 +0,0 @@
-[
-  {
-    "marker": {
-      "fileName": "/tests/cases/fourslash/quickInfoEvolvingArrayType.ts",
-      "position": 45,
-      "name": "1"
-    },
-    "quickInfo": {
-      "kind": "method",
-      "kindModifiers": "declare",
-      "textSpan": {
-        "start": 39,
-        "length": 14
-      },
-      "displayParts": [
-        {
-          "text": "(",
-          "kind": "punctuation"
-        },
-        {
-          "text": "method",
-          "kind": "text"
-        },
-        {
-          "text": ")",
-          "kind": "punctuation"
-        },
-        {
-          "text": " ",
-          "kind": "space"
-        },
-        {
-          "text": "Object",
-          "kind": "localName"
-        },
-        {
-          "text": ".",
-          "kind": "punctuation"
-        },
-        {
-          "text": "hasOwnProperty",
-          "kind": "methodName"
-        },
-        {
-          "text": "(",
-          "kind": "punctuation"
-        },
-        {
-          "text": "v",
-          "kind": "parameterName"
-        },
-        {
-          "text": ":",
-          "kind": "punctuation"
-        },
-        {
-          "text": " ",
-          "kind": "space"
-        },
-        {
-          "text": "PropertyKey",
-          "kind": "aliasName"
-        },
-        {
-          "text": ")",
-          "kind": "punctuation"
-        },
-        {
-          "text": ":",
-          "kind": "punctuation"
-        },
-        {
-          "text": " ",
-          "kind": "space"
-        },
-        {
-          "text": "boolean",
-          "kind": "keyword"
-        }
-      ],
-      "documentation": [
-        {
-          "text": "Determines whether an object has a property with the specified name.",
-          "kind": "text"
-        }
-      ],
-      "tags": [
-        {
-          "name": "param",
-          "text": [
-            {
-              "text": "v",
-              "kind": "parameterName"
-            },
-            {
-              "text": " ",
-              "kind": "space"
-            },
-            {
-              "text": "A property name.",
-              "kind": "text"
-            }
-          ]
-        }
-      ]
-    }
-  }
-]
\ No newline at end of file
diff --git a/tests/cases/compiler/evolvingArrayResolvedAssert.ts b/tests/cases/compiler/evolvingArrayResolvedAssert.ts
new file mode 100644
index 0000000000000..0a08459eb068d
--- /dev/null
+++ b/tests/cases/compiler/evolvingArrayResolvedAssert.ts
@@ -0,0 +1,11 @@
+// @strict: true
+// @checkJs: true
+// @allowJs: true
+// @outDir: ./out
+
+// @filename: index.js
+var C = [];
+for (var a in C) {
+    if (C.hasOwnProperty(a)) {
+    }
+}
diff --git a/tests/cases/fourslash/quickInfoEvolvingArrayType.ts b/tests/cases/fourslash/quickInfoEvolvingArrayType.ts
deleted file mode 100644
index c16d905b4a0a5..0000000000000
--- a/tests/cases/fourslash/quickInfoEvolvingArrayType.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-///<reference path="fourslash.ts" />
-
-// @strict: true
-// @checkJs: true
-// @allowJs: true
-// @outDir: ./dist
-
-// filename: index.js
-//// var C = [];
-//// for (var a in C)
-////     if (C.hasOwn/*1*/Property(a)) {
-////     }
-//// }
-
-verify.baselineQuickInfo();

From 7d14f8849b9b9444a42b8b5492d5db483f040a2e Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Mon, 18 Jul 2022 18:10:09 -0700
Subject: [PATCH 3/3] Just use TS

---
 .../reference/evolvingArrayResolvedAssert.errors.txt |  8 ++++----
 .../reference/evolvingArrayResolvedAssert.js         |  4 ++--
 .../reference/evolvingArrayResolvedAssert.symbols    | 12 ++++++------
 .../reference/evolvingArrayResolvedAssert.types      |  2 +-
 tests/cases/compiler/evolvingArrayResolvedAssert.ts  |  4 ----
 5 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt b/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt
index 9c21c78820279..487ffa3a82a12 100644
--- a/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.errors.txt
@@ -1,9 +1,9 @@
-tests/cases/compiler/index.js(1,5): error TS7034: Variable 'C' implicitly has type 'any[]' in some locations where its type cannot be determined.
-tests/cases/compiler/index.js(2,15): error TS7005: Variable 'C' implicitly has an 'any[]' type.
-tests/cases/compiler/index.js(3,9): error TS7005: Variable 'C' implicitly has an 'any[]' type.
+tests/cases/compiler/evolvingArrayResolvedAssert.ts(1,5): error TS7034: Variable 'C' implicitly has type 'any[]' in some locations where its type cannot be determined.
+tests/cases/compiler/evolvingArrayResolvedAssert.ts(2,15): error TS7005: Variable 'C' implicitly has an 'any[]' type.
+tests/cases/compiler/evolvingArrayResolvedAssert.ts(3,9): error TS7005: Variable 'C' implicitly has an 'any[]' type.
 
 
-==== tests/cases/compiler/index.js (3 errors) ====
+==== tests/cases/compiler/evolvingArrayResolvedAssert.ts (3 errors) ====
     var C = [];
         ~
 !!! error TS7034: Variable 'C' implicitly has type 'any[]' in some locations where its type cannot be determined.
diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.js b/tests/baselines/reference/evolvingArrayResolvedAssert.js
index 0ffb6e71de6b9..4cae93bbb8645 100644
--- a/tests/baselines/reference/evolvingArrayResolvedAssert.js
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.js
@@ -1,4 +1,4 @@
-//// [index.js]
+//// [evolvingArrayResolvedAssert.ts]
 var C = [];
 for (var a in C) {
     if (C.hasOwnProperty(a)) {
@@ -6,7 +6,7 @@ for (var a in C) {
 }
 
 
-//// [index.js]
+//// [evolvingArrayResolvedAssert.js]
 "use strict";
 var C = [];
 for (var a in C) {
diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.symbols b/tests/baselines/reference/evolvingArrayResolvedAssert.symbols
index 8afcfab09152c..8d52f9e5d0266 100644
--- a/tests/baselines/reference/evolvingArrayResolvedAssert.symbols
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.symbols
@@ -1,16 +1,16 @@
-=== tests/cases/compiler/index.js ===
+=== tests/cases/compiler/evolvingArrayResolvedAssert.ts ===
 var C = [];
->C : Symbol(C, Decl(index.js, 0, 3))
+>C : Symbol(C, Decl(evolvingArrayResolvedAssert.ts, 0, 3))
 
 for (var a in C) {
->a : Symbol(a, Decl(index.js, 1, 8))
->C : Symbol(C, Decl(index.js, 0, 3))
+>a : Symbol(a, Decl(evolvingArrayResolvedAssert.ts, 1, 8))
+>C : Symbol(C, Decl(evolvingArrayResolvedAssert.ts, 0, 3))
 
     if (C.hasOwnProperty(a)) {
 >C.hasOwnProperty : Symbol(Object.hasOwnProperty, Decl(lib.es5.d.ts, --, --))
->C : Symbol(C, Decl(index.js, 0, 3))
+>C : Symbol(C, Decl(evolvingArrayResolvedAssert.ts, 0, 3))
 >hasOwnProperty : Symbol(Object.hasOwnProperty, Decl(lib.es5.d.ts, --, --))
->a : Symbol(a, Decl(index.js, 1, 8))
+>a : Symbol(a, Decl(evolvingArrayResolvedAssert.ts, 1, 8))
     }
 }
 
diff --git a/tests/baselines/reference/evolvingArrayResolvedAssert.types b/tests/baselines/reference/evolvingArrayResolvedAssert.types
index 91e5d706fb29c..b0524c275c117 100644
--- a/tests/baselines/reference/evolvingArrayResolvedAssert.types
+++ b/tests/baselines/reference/evolvingArrayResolvedAssert.types
@@ -1,4 +1,4 @@
-=== tests/cases/compiler/index.js ===
+=== tests/cases/compiler/evolvingArrayResolvedAssert.ts ===
 var C = [];
 >C : any[]
 >[] : never[]
diff --git a/tests/cases/compiler/evolvingArrayResolvedAssert.ts b/tests/cases/compiler/evolvingArrayResolvedAssert.ts
index 0a08459eb068d..7ba37947b0414 100644
--- a/tests/cases/compiler/evolvingArrayResolvedAssert.ts
+++ b/tests/cases/compiler/evolvingArrayResolvedAssert.ts
@@ -1,9 +1,5 @@
 // @strict: true
-// @checkJs: true
-// @allowJs: true
-// @outDir: ./out
 
-// @filename: index.js
 var C = [];
 for (var a in C) {
     if (C.hasOwnProperty(a)) {