[dartdevc] Add details to failed assertion messages

* Source file location
* Assertion source code

This change embeds the information as strings into the compiled source. In the
future we could reconstruct the source file location at runtime from the stack
trace.

In tests with various large applications this added roughly 1MB (0.1MB
compressed) or less to the compiled file size.

Fixes: flutter#36995
Change-Id: I2634f7eab6e54eec209094b52429987dd62c0828
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103568
Reviewed-by: Vijay Menon <vsm@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>

Author: nshahan

pkg/dev_compiler/lib/src/analyzer/code_generator.dart

@@ -4150,10 +4150,20 @@ class CodeGenerator extends Object
     } else if (isNullable(condition)) {
       jsCondition = runtimeCall('test(#)', [jsCondition]);
     }
-    return js.statement(' if (!#) #.assertFailed(#);', [
+
+    var location = _getLocation(condition.offset);
+    return js.statement(' if (!#) #.assertFailed(#, #, #, #, #);', [
       jsCondition,
       runtimeModule,
-      message != null ? [_visitExpression(message)] : []
+      if (message == null)
+        JS.LiteralNull()
+      else
+        _visitExpression(message),
+      js.escapedString(location.sourceUrl.toString()),
+      // Lines and columns are typically printed with 1 based indexing.
+      js.number(location.line + 1),
+      js.number(location.column + 1),
+      js.escapedString(condition.toSource()),
     ]);
   }
 

pkg/dev_compiler/lib/src/kernel/compiler.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection';
+import 'dart:convert';
 import 'dart:math' show max, min;
 
 import 'package:front_end/src/api_unstable/ddc.dart' show TypeSchemaEnvironment;
@@ -3185,10 +3186,24 @@ class ProgramCompiler extends Object
     } else if (isNullable(condition)) {
       jsCondition = runtimeCall('test(#)', [jsCondition]);
     }
-    return js.statement(' if (!#) #.assertFailed(#);', [
+
+    var encodedConditionSource = node
+        .enclosingComponent.uriToSource[node.location.file].source
+        .sublist(node.conditionStartOffset, node.conditionEndOffset);
+    var conditionSource = utf8.decode(encodedConditionSource);
+    var location = _getLocation(node.conditionStartOffset);
+    return js.statement(' if (!#) #.assertFailed(#, #, #, #, #);', [
       jsCondition,
       runtimeModule,
-      node.message != null ? [_visitExpression(node.message)] : []
+      if (node.message == null)
+        JS.LiteralNull()
+      else
+        _visitExpression(node.message),
+      js.escapedString(location.sourceUrl.toString()),
+      // Lines and columns are typically printed with 1 based indexing.
+      js.number(location.line + 1),
+      js.number(location.column + 1),
+      js.escapedString(conditionSource),
     ]);
   }
 

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart

@@ -33,9 +33,13 @@ throwUnimplementedError(String message) {
   throw UnimplementedError(message);
 }
 
-assertFailed(message) {
+// TODO(nshahan) Cleanup embeded strings and extract file location at runtime
+// from the stacktrace.
+assertFailed(String message,
+    [String fileUri, int line, int column, String conditionSource]) {
   if (JS('!', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
-  throw AssertionErrorImpl(message);
+
+  throw AssertionErrorImpl(message, fileUri, line, column, conditionSource);
 }
 
 throwCyclicInitializationError([Object field]) {

pkg/dev_compiler/tool/input_sdk/private/js_helper.dart

@@ -738,10 +738,28 @@ class RuntimeError extends Error {
 
 /// Error thrown by DDC when an `assert()` fails (with or without a message).
 class AssertionErrorImpl extends AssertionError {
-  AssertionErrorImpl(message) : super(message);
-  String toString() =>
-      "Assertion failed: " +
-      (message != null ? Error.safeToString(message) : "is not true");
+  final String _fileUri;
+  final int _line;
+  final int _column;
+  final String _conditionSource;
+
+  AssertionErrorImpl(Object message,
+      [this._fileUri, this._line, this._column, this._conditionSource])
+      : super(message);
+
+  String toString() {
+    var failureMessage = "";
+    if (_fileUri != null &&
+        _line != null &&
+        _column != null &&
+        _conditionSource != null) {
+      failureMessage += "$_fileUri:${_line}:${_column}\n$_conditionSource\n";
+    }
+    failureMessage +=
+        message != null ? Error.safeToString(message) : "is not true";
+
+    return "Assertion failed: $failureMessage";
+  }
 }
 
 /**