From cf57f882ca8610ce41d35546b0c9ceea271e7b4f Mon Sep 17 00:00:00 2001
From: Nicholas Shahan <nshahan@google.com>
Date: Fri, 10 Jul 2020 17:42:55 +0000
Subject: [PATCH] [ddc] Change `!` failure to a throw TypeError

Fixes test failures in language/unsorted/inv_cse_licm_test

Change-Id: If8df024d0128568e1f65463d4a82fa593b5a6a1d
Fixes: https://github.com/dart-lang/sdk/issues/42443
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153481
Reviewed-by: Mark Zhou <markzipan@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>
---
 pkg/dev_compiler/lib/src/kernel/compiler.dart |  3 ++-
 .../private/ddc_runtime/operations.dart       | 25 ++++++++++++++-----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/pkg/dev_compiler/lib/src/kernel/compiler.dart b/pkg/dev_compiler/lib/src/kernel/compiler.dart
index d6f0fa523cc6..4ed43fadc9ae 100644
--- a/pkg/dev_compiler/lib/src/kernel/compiler.dart
+++ b/pkg/dev_compiler/lib/src/kernel/compiler.dart
@@ -5212,8 +5212,9 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   @override
   js_ast.Expression visitNullCheck(NullCheck node) {
     var expr = node.operand;
+    var jsExpr = _visitExpression(expr);
     // If the expression is non-nullable already, this is a no-op.
-    return isNullable(expr) ? notNull(expr) : _visitExpression(expr);
+    return isNullable(expr) ? runtimeCall('nullCheck(#)', [jsExpr]) : jsExpr;
   }
 
   @override
diff --git a/sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart b/sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart
index fd9a7d40ecf4..fefa3b8252f1 100644
--- a/sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart
+++ b/sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart
@@ -474,7 +474,9 @@ asInt(obj) {
 
 asNullableInt(obj) => obj == null ? null : asInt(obj);
 
-/// Checks that `x` is not null or undefined.
+/// Checks for null or undefined and returns [x].
+///
+/// Throws [NoSuchMethodError] when it is null or undefined.
 //
 // TODO(jmesserly): inline this, either by generating it as a function into
 // the module, or via some other pattern such as:
@@ -487,12 +489,13 @@ _notNull(x) {
   return x;
 }
 
-/// Checks that `x` is not null or undefined.
+/// Checks for null or undefined and returns [x].
+///
+/// Throws a [TypeError] when [x] is null or undefined (under sound null safety
+/// mode) or emits a runtime warning (otherwise).
 ///
-/// Unlike `_notNull`, this throws a `CastError` (under strict checking)
-/// or emits a runtime warning (otherwise).  This is only used by the
-/// compiler when casting from nullable to non-nullable variants of the
-/// same type.
+/// This is only used by the compiler when casting from nullable to non-nullable
+/// variants of the same type.
 nullCast(x, type) {
   if (x == null) {
     if (!strictNullSafety) {
@@ -504,6 +507,16 @@ nullCast(x, type) {
   return x;
 }
 
+/// Checks for null or undefined and returns [x].
+///
+/// Throws a [TypeError] when [x] is null or undefined.
+///
+/// This is only used by the compiler for the runtime null check operator `!`.
+nullCheck(x) {
+  if (x == null) throw TypeErrorImpl("Unexpected null value.");
+  return x;
+}
+
 /// The global constant map table.
 final constantMaps = JS<Object>('!', 'new Map()');