Rename build-root to library-root

First step on #557.  Will eliminate the deprecated flag once upstream
uses are switched over.

R=jmesserly@google.com

Review URL: https://codereview.chromium.org/2197243002 .

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

@@ -130,7 +130,7 @@ class CodeGenerator extends GeneralizingAstVisitor
 
   BuildUnit _buildUnit;
 
-  String _buildRoot;
+  String _libraryRoot;
 
   bool _superAllowed = true;
 
@@ -168,9 +168,9 @@ class CodeGenerator extends GeneralizingAstVisitor
   JSModuleFile compile(BuildUnit unit, List<CompilationUnit> compilationUnits,
       List<String> errors) {
     _buildUnit = unit;
-    _buildRoot = _buildUnit.buildRoot;
-    if (!_buildRoot.endsWith(separator)) {
-      _buildRoot = '$_buildRoot${separator}';
+    _libraryRoot = _buildUnit.libraryRoot;
+    if (!_libraryRoot.endsWith(separator)) {
+      _libraryRoot = '$_libraryRoot${separator}';
     }
 
     var jsTree = _emitModule(compilationUnits);
@@ -231,7 +231,7 @@ class CodeGenerator extends GeneralizingAstVisitor
 
       var libraryTemp = _isDartRuntime(library)
           ? _runtimeLibVar
-          : new JS.TemporaryId(jsLibraryName(_buildRoot, library));
+          : new JS.TemporaryId(jsLibraryName(_libraryRoot, library));
       _libraries[library] = libraryTemp;
       items.add(new JS.ExportDeclaration(
           js.call('const # = Object.create(null)', [libraryTemp])));
@@ -5189,7 +5189,7 @@ class CodeGenerator extends GeneralizingAstVisitor
     // It's either one of the libraries in this module, or it's an import.
     return _libraries[library] ??
         _imports.putIfAbsent(library,
-            () => new JS.TemporaryId(jsLibraryName(_buildRoot, library)));
+            () => new JS.TemporaryId(jsLibraryName(_libraryRoot, library)));
   }
 
   JS.Node/*=T*/ annotate/*<T extends JS.Node>*/(
@@ -5315,7 +5315,7 @@ class CodeGenerator extends GeneralizingAstVisitor
 /// Choose a canonical name from the library element.
 /// This never uses the library's name (the identifier in the `library`
 /// declaration) as it doesn't have any meaningful rules enforced.
-String jsLibraryName(String buildRoot, LibraryElement library) {
+String jsLibraryName(String libraryRoot, LibraryElement library) {
   var uri = library.source.uri;
   if (uri.scheme == 'dart') {
     return uri.path;
@@ -5328,12 +5328,12 @@ String jsLibraryName(String buildRoot, LibraryElement library) {
     // TODO(vsm): This is not unique if an escaped '/'appears in a filename.
     // E.g., "foo/bar.dart" and "foo$47bar.dart" would collide.
     qualifiedPath = uri.pathSegments.skip(1).join(separator);
-  } else if (uri.toFilePath().startsWith(buildRoot)) {
+  } else if (uri.toFilePath().startsWith(libraryRoot)) {
     qualifiedPath =
-        uri.path.substring(buildRoot.length).replaceAll('/', separator);
+        uri.path.substring(libraryRoot.length).replaceAll('/', separator);
   } else {
     // We don't have a unique name.
-    throw 'Invalid build root. $buildRoot does not contain ${uri.toFilePath()}';
+    throw 'Invalid library root. $libraryRoot does not contain ${uri.toFilePath()}';
   }
   return pathToJSIdentifier(qualifiedPath);
 }

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

@@ -26,9 +26,11 @@ class CompileCommand extends Command {
     argParser.addOption('module-root',
         help: 'Root module directory. '
             'Generated module paths are relative to this root.');
-    argParser.addOption('build-root',
+    argParser.addOption('library-root',
         help: 'Root of source files. '
             'Generated library names are relative to this root.');
+    argParser.addOption('build-root',
+        help: 'Deprecated in favor of --library-root');
     CompilerOptions.addArguments(argParser);
     AnalyzerOptions.addArguments(argParser);
   }
@@ -48,11 +50,12 @@ class CompileCommand extends Command {
           '    -o PATH/TO/OUTPUT_FILE.js');
     }
 
-    var buildRoot = argResults['build-root'] as String;
-    if (buildRoot != null) {
-      buildRoot = path.absolute(buildRoot);
+    var libraryRoot = argResults['library-root'] as String;
+    libraryRoot ??= argResults['build-root'] as String;
+    if (libraryRoot != null) {
+      libraryRoot = path.absolute(libraryRoot);
     } else {
-      buildRoot = Directory.current.path;
+      libraryRoot = Directory.current.path;
     }
     var moduleRoot = argResults['module-root'] as String;
     String modulePath;
@@ -73,7 +76,7 @@ class CompileCommand extends Command {
       usageException('Please pass at least one source file as an argument.');
     }
 
-    var unit = new BuildUnit(modulePath, buildRoot, argResults.rest,
+    var unit = new BuildUnit(modulePath, libraryRoot, argResults.rest,
         (source) => _moduleForLibrary(moduleRoot, source));
 
     JSModuleFile module = compiler.compile(unit, _compilerOptions);

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

@@ -292,8 +292,8 @@ class BuildUnit {
   /// The name of this module.
   final String name;
 
-  /// Build root.  All library names are relative to this path/prefix.
-  final String buildRoot;
+  /// Library root.  All library names are relative to this path/prefix.
+  final String libraryRoot;
 
   /// The list of sources in this module.
   ///
@@ -308,7 +308,7 @@ class BuildUnit {
   // build units.
   final Func1<Source, String> libraryToModule;
 
-  BuildUnit(this.name, this.buildRoot, this.sources, this.libraryToModule);
+  BuildUnit(this.name, this.libraryRoot, this.sources, this.libraryToModule);
 }
 
 /// The output of Dart->JS compilation.