Report messages instead of just printing.

pkg/front_end/lib/src/fasta/command_line_reporting.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Provides a default implementation of the report and format methods of
+/// [CompilerContext] that are suitable for command-line tools. The methods in
+/// this library aren't intended to be called directly, instead, one should use
+/// [CompilerContext].
+library fasta.command_line_reporting;
+
+import 'dart:io' show exitCode;
+
+import 'package:kernel/ast.dart' show Location;
+
+import 'colors.dart' show cyan, magenta, red;
+
+import 'compiler_context.dart' show CompilerContext;
+
+import 'deprecated_problems.dart' show deprecated_InputError;
+
+import 'fasta_codes.dart' show LocatedMessage, Message;
+
+import 'messages.dart' show getLocation, getSourceLine, isVerbose;
+
+import 'problems.dart' show unhandled;
+
+import 'severity.dart' show Severity;
+
+import 'util/relativize.dart' show relativizeUri;
+
+const bool hideWarnings = false;
+
+/// Formats [message] as a string that is suitable for output from a
+/// command-line tool. This includes source snippets and different colors based
+/// on [severity].
+///
+/// It is a assumed that a formatted message is reported to a user, so
+/// [exitCode] is also set depending on the value of
+/// `CompilerContext.current.options.setExitCodeOnProblem`.
+///
+/// This is shared implementation used by methods below, and isn't intended to
+/// be called directly.
+String formatInternal(Message message, Severity severity, Uri uri, int offset) {
+  if (CompilerContext.current.options.setExitCodeOnProblem) {
+    exitCode = 1;
+  }
+  String text =
+      "${severityName(severity, capitalized: true)}: ${message.message}";
+  if (message.tip != null) {
+    text += "\n${message.tip}";
+  }
+  if (CompilerContext.enableColors) {
+    switch (severity) {
+      case Severity.error:
+      case Severity.internalProblem:
+        text = red(text);
+        break;
+
+      case Severity.nit:
+        text = cyan(text);
+        break;
+
+      case Severity.warning:
+        text = magenta(text);
+        break;
+    }
+  }
+
+  if (uri != null) {
+    String path = relativizeUri(uri);
+    Location location = offset == -1 ? null : getLocation(path, offset);
+    String sourceLine = getSourceLine(location);
+    if (sourceLine == null) {
+      sourceLine = "";
+    } else {
+      sourceLine = "\n$sourceLine\n"
+          "${' ' * (location.column - 1)}^";

[Siggi Cherem (dart-lang), 2017/07/13 21:05:56]

BTW this is logic for which I'd like to use package:source_span. Consider adding
a TODO to revisit this afterwards?

[ahe, 2017/07/14 10:01:07]

Done.

+    }
+    String position = location?.toString() ?? path;
+    return "$position: $text$sourceLine";
+  } else {
+    return text;
+  }
+}
+
+/// Are problems of [severity] suppressed?
+bool isHidden(Severity severity) {
+  switch (severity) {
+    case Severity.error:
+    case Severity.internalProblem:
+      return false;
+
+    case Severity.nit:
+      return !isVerbose;
+
+    case Severity.warning:
+      return hideWarnings;
+  }
+  return unhandled("$severity", "isHidden", -1, null);
+}
+
+/// Are problems of [severity] fatal? That is, should the compiler terminate
+/// immediately?
+bool isFatal(Severity severity) {
+  switch (severity) {
+    case Severity.error:
+      return CompilerContext.current.options.errorsAreFatal;
+
+    case Severity.internalProblem:
+      return true;
+
+    case Severity.nit:
+      return CompilerContext.current.options.nitsAreFatal;
+
+    case Severity.warning:
+      return CompilerContext.current.options.warningsAreFatal;
+  }
+  return unhandled("$severity", "isFatal", -1, null);
+}
+
+/// Convert [severity] to a name that can be used to prefix a message.
+String severityName(Severity severity, {bool capitalized: false}) {
+  switch (severity) {
+    case Severity.error:
+      return capitalized ? "Error" : "error";
+
+    case Severity.internalProblem:
+      return capitalized ? "Internal problem" : "internal problem";
+
+    case Severity.nit:
+      return capitalized ? "Nit" : "nit";
+
+    case Severity.warning:
+      return capitalized ? "Warning" : "warning";
+  }
+  return unhandled("$severity", "severityName", -1, null);
+}
+
+/// Report [message] unless [severity] is suppressed (see [isHidden]). Throws
+/// an exception if [severity] is fatal (see [isFatal]).
+///
+/// This method isn't intended to be called directly. Use
+/// [CompilerContext.report] instead.
+void report(LocatedMessage message, Severity severity) {
+  if (isHidden(severity)) return;
+  print(format(message, severity));
+  if (isFatal(severity)) {
+    if (isVerbose) print(StackTrace.current);
+    throw new deprecated_InputError(message.uri, message.charOffset,
+        "Compilation aborted due to fatal ${severityName(severity)}.");
+  }
+}
+
+/// Similar to [report].
+///
+/// This method isn't intended to be called directly. Use
+/// [CompilerContext.reportWithoutLocation] instead.
+void reportWithoutLocation(Message message, Severity severity) {
+  if (isHidden(severity)) return;
+  print(formatWithoutLocation(message, severity));
+  if (isFatal(severity)) {

[Siggi Cherem (dart-lang), 2017/07/13 21:05:56]

considering adding a common shared function to avoid the duplication here and
above. 

Maybe do the printing and isFatal check together, like:

void printAndThowIfFatal(String message, Severity severity) {
}

?

that way there is only one place with a `print`?

[ahe, 2017/07/14 10:01:07]

Done.

+    if (isVerbose) print(StackTrace.current);
+    throw new deprecated_InputError(null, -1,
+        "Compilation aborted due to fatal ${severityName(severity)}.");
+  }
+}
+
+/// Formats [message] as described in [formatInternal].
+///
+/// This method isn't intended to be called directly. Use
+/// [CompilerContext.format] instead.
+String format(LocatedMessage message, Severity severity) {
+  return formatInternal(
+      message.messageObject, severity, message.uri, message.charOffset);
+}
+
+/// Formats [message] as described in [formatInternal].
+///
+/// This method isn't intended to be called directly. Use
+/// [CompilerContext.formatWithoutLocation] instead.
+String formatWithoutLocation(Message message, Severity severity) {
+  return formatInternal(message, severity, null, -1);
+}