From 214ef0c7502b6b792d45431dcb05560d8dfc303a Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Wed, 3 Feb 2021 11:32:48 -0800
Subject: [PATCH 1/2] No did-you-mean-to-call error on casts

I chose to do the ad-hoc check rather than yet another tree walk.

1. It's faster to run and easier to read.
2. This error came from looking at real code. It happened twice, so I
think the best estimate for other uses that happened zero times is in
fact zero.
3. I couldn't think of other places to put the cast, given the
restrictions on `testedNode` just before the new code.
---
 src/compiler/checker.ts                       |  5 +++-
 .../truthinessCallExpressionCoercion3.js      | 19 +++++++++++++++
 .../truthinessCallExpressionCoercion3.symbols | 24 +++++++++++++++++++
 .../truthinessCallExpressionCoercion3.types   | 23 ++++++++++++++++++
 .../truthinessCallExpressionCoercion3.ts      | 13 ++++++++++
 5 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/truthinessCallExpressionCoercion3.js
 create mode 100644 tests/baselines/reference/truthinessCallExpressionCoercion3.symbols
 create mode 100644 tests/baselines/reference/truthinessCallExpressionCoercion3.types
 create mode 100644 tests/cases/compiler/truthinessCallExpressionCoercion3.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index c4b3d67ad6d96..c1c7a73c46c86 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -34554,8 +34554,11 @@ namespace ts {
                 : isPropertyAccessExpression(location) ? location.name
                 : isBinaryExpression(location) && isIdentifier(location.right) ? location.right
                 : undefined;
+            const isPropertyExpressionCast = isPropertyAccessExpression(location)
+                && isParenthesizedExpression(location.expression)
+                && isAssertionExpression(location.expression.expression);
 
-            if (!testedNode) {
+            if (!testedNode || isPropertyExpressionCast) {
                 return;
             }
 
diff --git a/tests/baselines/reference/truthinessCallExpressionCoercion3.js b/tests/baselines/reference/truthinessCallExpressionCoercion3.js
new file mode 100644
index 0000000000000..a2ab27f21a2ef
--- /dev/null
+++ b/tests/baselines/reference/truthinessCallExpressionCoercion3.js
@@ -0,0 +1,19 @@
+//// [truthinessCallExpressionCoercion3.ts]
+// from #41640, based on an example in ant-design
+interface I {
+    always(): void
+}
+
+function f(result: unknown) {
+    if ((result as I).always) {
+        return result
+    }
+}
+
+
+//// [truthinessCallExpressionCoercion3.js]
+function f(result) {
+    if (result.always) {
+        return result;
+    }
+}
diff --git a/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols b/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols
new file mode 100644
index 0000000000000..35392c06aef0e
--- /dev/null
+++ b/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols
@@ -0,0 +1,24 @@
+=== tests/cases/compiler/truthinessCallExpressionCoercion3.ts ===
+// from #41640, based on an example in ant-design
+interface I {
+>I : Symbol(I, Decl(truthinessCallExpressionCoercion3.ts, 0, 0))
+
+    always(): void
+>always : Symbol(I.always, Decl(truthinessCallExpressionCoercion3.ts, 1, 13))
+}
+
+function f(result: unknown) {
+>f : Symbol(f, Decl(truthinessCallExpressionCoercion3.ts, 3, 1))
+>result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 5, 11))
+
+    if ((result as I).always) {
+>(result as I).always : Symbol(I.always, Decl(truthinessCallExpressionCoercion3.ts, 1, 13))
+>result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 5, 11))
+>I : Symbol(I, Decl(truthinessCallExpressionCoercion3.ts, 0, 0))
+>always : Symbol(I.always, Decl(truthinessCallExpressionCoercion3.ts, 1, 13))
+
+        return result
+>result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 5, 11))
+    }
+}
+
diff --git a/tests/baselines/reference/truthinessCallExpressionCoercion3.types b/tests/baselines/reference/truthinessCallExpressionCoercion3.types
new file mode 100644
index 0000000000000..200ddbfa13ecc
--- /dev/null
+++ b/tests/baselines/reference/truthinessCallExpressionCoercion3.types
@@ -0,0 +1,23 @@
+=== tests/cases/compiler/truthinessCallExpressionCoercion3.ts ===
+// from #41640, based on an example in ant-design
+interface I {
+    always(): void
+>always : () => void
+}
+
+function f(result: unknown) {
+>f : (result: unknown) => unknown
+>result : unknown
+
+    if ((result as I).always) {
+>(result as I).always : () => void
+>(result as I) : I
+>result as I : I
+>result : unknown
+>always : () => void
+
+        return result
+>result : unknown
+    }
+}
+
diff --git a/tests/cases/compiler/truthinessCallExpressionCoercion3.ts b/tests/cases/compiler/truthinessCallExpressionCoercion3.ts
new file mode 100644
index 0000000000000..69f6ba8214d40
--- /dev/null
+++ b/tests/cases/compiler/truthinessCallExpressionCoercion3.ts
@@ -0,0 +1,13 @@
+// @strictNullChecks: true
+// @lib: esnext,dom
+
+// from #41640, based on an example in ant-design
+interface I {
+    always(): void
+}
+
+function f(result: unknown) {
+    if ((result as I).always) {
+        return result
+    }
+}

From b3be79ad0f586073fefde73612b206eb27b427f9 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Fri, 12 Feb 2021 09:38:21 -0800
Subject: [PATCH 2/2] Skip parentheses

---
 src/compiler/checker.ts                          |  4 +---
 .../truthinessCallExpressionCoercion3.js         | 10 ++++++++++
 .../truthinessCallExpressionCoercion3.symbols    | 14 ++++++++++++++
 .../truthinessCallExpressionCoercion3.types      | 16 ++++++++++++++++
 .../truthinessCallExpressionCoercion3.ts         |  5 +++++
 5 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a8a14dc9b66a5..b155f3dfab106 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -34547,9 +34547,7 @@ namespace ts {
                 : isBinaryExpression(location) && isIdentifier(location.right) ? location.right
                 : undefined;
             const isPropertyExpressionCast = isPropertyAccessExpression(location)
-                && isParenthesizedExpression(location.expression)
-                && isAssertionExpression(location.expression.expression);
-
+                && isAssertionExpression(skipParentheses(location.expression));
             if (!testedNode || isPropertyExpressionCast) {
                 return;
             }
diff --git a/tests/baselines/reference/truthinessCallExpressionCoercion3.js b/tests/baselines/reference/truthinessCallExpressionCoercion3.js
index a2ab27f21a2ef..7fc1df8ffb574 100644
--- a/tests/baselines/reference/truthinessCallExpressionCoercion3.js
+++ b/tests/baselines/reference/truthinessCallExpressionCoercion3.js
@@ -9,6 +9,11 @@ function f(result: unknown) {
         return result
     }
 }
+function g(result: unknown) {
+    if (((result as I)).always) {
+        return result
+    }
+}
 
 
 //// [truthinessCallExpressionCoercion3.js]
@@ -17,3 +22,8 @@ function f(result) {
         return result;
     }
 }
+function g(result) {
+    if (result.always) {
+        return result;
+    }
+}
diff --git a/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols b/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols
index 35392c06aef0e..e7ed13514df6c 100644
--- a/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols
+++ b/tests/baselines/reference/truthinessCallExpressionCoercion3.symbols
@@ -21,4 +21,18 @@ function f(result: unknown) {
 >result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 5, 11))
     }
 }
+function g(result: unknown) {
+>g : Symbol(g, Decl(truthinessCallExpressionCoercion3.ts, 9, 1))
+>result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 10, 11))
+
+    if (((result as I)).always) {
+>((result as I)).always : Symbol(I.always, Decl(truthinessCallExpressionCoercion3.ts, 1, 13))
+>result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 10, 11))
+>I : Symbol(I, Decl(truthinessCallExpressionCoercion3.ts, 0, 0))
+>always : Symbol(I.always, Decl(truthinessCallExpressionCoercion3.ts, 1, 13))
+
+        return result
+>result : Symbol(result, Decl(truthinessCallExpressionCoercion3.ts, 10, 11))
+    }
+}
 
diff --git a/tests/baselines/reference/truthinessCallExpressionCoercion3.types b/tests/baselines/reference/truthinessCallExpressionCoercion3.types
index 200ddbfa13ecc..3d10a48a7f68e 100644
--- a/tests/baselines/reference/truthinessCallExpressionCoercion3.types
+++ b/tests/baselines/reference/truthinessCallExpressionCoercion3.types
@@ -20,4 +20,20 @@ function f(result: unknown) {
 >result : unknown
     }
 }
+function g(result: unknown) {
+>g : (result: unknown) => unknown
+>result : unknown
+
+    if (((result as I)).always) {
+>((result as I)).always : () => void
+>((result as I)) : I
+>(result as I) : I
+>result as I : I
+>result : unknown
+>always : () => void
+
+        return result
+>result : unknown
+    }
+}
 
diff --git a/tests/cases/compiler/truthinessCallExpressionCoercion3.ts b/tests/cases/compiler/truthinessCallExpressionCoercion3.ts
index 69f6ba8214d40..948e8059cf14a 100644
--- a/tests/cases/compiler/truthinessCallExpressionCoercion3.ts
+++ b/tests/cases/compiler/truthinessCallExpressionCoercion3.ts
@@ -11,3 +11,8 @@ function f(result: unknown) {
         return result
     }
 }
+function g(result: unknown) {
+    if (((result as I)).always) {
+        return result
+    }
+}