Invoke copy_tree.py only once to collect all input file lists.

sdk/BUILD.gn

Index: sdk/BUILD.gn
diff --git a/sdk/BUILD.gn b/sdk/BUILD.gn
index 6ec91aeaba7524ef29cd30ff56dd321f3b11d584..82a9a1ab2334d3dd6bc691348a4aedc7d051e564 100644
--- a/sdk/BUILD.gn
+++ b/sdk/BUILD.gn
@@ -210,6 +210,103 @@ _analyzer_source_dirs = [
   "kernel",
 ]
 
+# From here down to the copy_trees() invocation, we collect all the information
+# about trees that need to be copied in the list of scopes, copy_tree_specs.
+copy_tree_specs = []
+
+# This loop generates rules for copying analyzer sources into lib/
+foreach(analyzer_source_dir, _analyzer_source_dirs) {
+  copy_tree_specs += [{
+    target = "copy_${analyzer_source_dir}_source_dir"
+    visibility = [ ":copy_analyzer_sources" ]
+    source = "../pkg/$analyzer_source_dir"
+    dest = "$root_out_dir/dart-sdk/lib/$analyzer_source_dir"
+    ignore_patterns = "*.svn,doc,*.py,*.gypi,*.sh,.gitignore,packages,test,testcases"
+  }]
+}
+
+# This rule copies dartdoc templates to
+# bin/snapshots/resources/dartdoc/templates
+copy_tree_specs += [{
+  target = "copy_dartdoc_templates"
+  visibility = [ ":copy_dartdoc_files" ]
+  source = "../third_party/pkg/dartdoc/lib/templates"
+  dest = "$root_out_dir/dart-sdk/bin/snapshots/resources/dartdoc/templates"
+  ignore_patterns = "{}"
+}]
+
+# This rule copies dartdoc resources to
+# bin/snapshots/resources/dartdoc/resources
+copy_tree_specs += [{
+  target = "copy_dartdoc_resources"
+  visibility = [ ":copy_dartdoc_files" ]
+  source = "../third_party/pkg/dartdoc/lib/resources"
+  dest = "$root_out_dir/dart-sdk/bin/snapshots/resources/dartdoc/resources"
+  ignore_patterns = "{}"
+}]
+
+# This rule copies js needed by ddc to lib/dev_compiler
+copy_tree_specs += [{
+  target = "copy_dev_compiler_js"
+  visibility = [
+    ":copy_dev_compiler_sdk",
+    ":copy_dev_compiler_require_js",
+    ":copy_dev_compiler_tools",
+  ]
+  source = "../pkg/dev_compiler/lib/js"
+  dest = "$root_out_dir/dart-sdk/lib/dev_compiler"
+  ignore_patterns = "{}"
+}]
+
+# This rule copies pub assets to lib/_internal/pub/asset
+copy_tree_specs += [{
+  target = "copy_pub_assets"
+  visibility = [
+    ":create_common_sdk",
+    ":copy_7zip",
+  ]
+  deps = [
+    ":copy_libraries",
+  ]
+  source = "../third_party/pkg/pub/lib/src/asset"
+  dest = "$root_out_dir/dart-sdk/lib/_internal/pub/asset"
+  ignore_patterns = "{}"
+}]
+
+# This loop generates rules to copy libraries to lib/
+foreach(library, _full_sdk_libraries) {
+  copy_tree_specs += [{
+    target = "copy_${library}_library"
+    visibility = [
+      ":copy_platform_sdk_libraries",
+      ":copy_full_sdk_libraries",
+    ]
+    source = "lib/$library"
+    dest = "$root_out_dir/dart-sdk/lib/$library"
+    ignore_patterns = "*.svn,doc,*.py,*.gypi,*.sh,.gitignore"
+  }]
+}
+
+if (is_win) {
+  copy_tree_specs += [{
+    target = "copy_7zip"
+    visibility = [ ":create_common_sdk" ]
+    deps = [
+      ":copy_libraries",
+      ":copy_pub_assets",
+    ]
+    source = "../third_party/7zip"
+    dest = "$root_out_dir/dart-sdk/lib/_internal/pub/asset/7zip"
+    ignore_patterns = ".svn"
+  }]
+}
+
+# This generates targets for everything in copy_tree_specs. The targets have the
+# same name as the "target" fields in the scopes of copy_tree_specs.
+copy_trees("copy_trees") {
+  sources = copy_tree_specs
+}
+
 # Copies the Dart VM binary into bin/
 copy("copy_dart") {
   visibility = [ ":create_common_sdk" ]
@@ -372,16 +469,6 @@ group("copy_full_sdk_snapshots") {
   }
 }
 
-# This loop generates rules for copying analyzer sources into lib/
-foreach(analyzer_source_dir, _analyzer_source_dirs) {
-  copy_tree("copy_${analyzer_source_dir}_source_dir") {
-    visibility = [ ":copy_analyzer_sources" ]
-    source = "../pkg/$analyzer_source_dir"
-    dest = "$root_out_dir/dart-sdk/lib/$analyzer_source_dir"
-    exclude = "*.svn,doc,*.py,*.gypi,*.sh,.gitignore,packages,test,testcases"
-  }
-}
-
 # This is the main rule for copying analyzer sources to lib/
 group("copy_analyzer_sources") {
   visibility = [ ":create_common_sdk" ]
@@ -391,22 +478,6 @@ group("copy_analyzer_sources") {
   }
 }
 
-# This rule copies dartdoc templates to
-# bin/snapshots/resources/dartdoc/templates
-copy_tree("copy_dartdoc_templates") {
-  visibility = [ ":copy_dartdoc_files" ]
-  source = "../third_party/pkg/dartdoc/lib/templates"
-  dest = "$root_out_dir/dart-sdk/bin/snapshots/resources/dartdoc/templates"
-}
-
-# This rule copies dartdoc resources to
-# bin/snapshots/resources/dartdoc/resources
-copy_tree("copy_dartdoc_resources") {
-  visibility = [ ":copy_dartdoc_files" ]
-  source = "../third_party/pkg/dartdoc/lib/resources"
-  dest = "$root_out_dir/dart-sdk/bin/snapshots/resources/dartdoc/resources"
-}
-
 # This rule writes the .packages file for dartdoc resources.
 write_file("$root_out_dir/dart-sdk/bin/snapshots/resources/dartdoc/.packages",
            "dartdoc:.")
@@ -481,17 +552,6 @@ copy("copy_dev_compiler_summary") {
   ]
 }
 
-# This rule copies js needed by ddc to lib/dev_compiler
-copy_tree("copy_dev_compiler_js") {
-  visibility = [
-    ":copy_dev_compiler_sdk",
-    ":copy_dev_compiler_require_js",
-    ":copy_dev_compiler_tools",
-  ]
-  source = "../pkg/dev_compiler/lib/js"
-  dest = "$root_out_dir/dart-sdk/lib/dev_compiler"
-}
-
 # This rule copies require.js to lib/dev_compiler/amd
 copy("copy_dev_compiler_require_js") {
   visibility = [ ":copy_dev_compiler_sdk" ]
@@ -562,32 +622,6 @@ copy("copy_platform_files") {
   ]
 }
 
-# This rule copies pub assets to lib/_internal/pub/asset
-copy_tree("copy_pub_assets") {
-  visibility = [
-    ":create_common_sdk",
-    ":copy_7zip",
-  ]
-  deps = [
-    ":copy_libraries",
-  ]
-  source = "../third_party/pkg/pub/lib/src/asset"
-  dest = "$root_out_dir/dart-sdk/lib/_internal/pub/asset"
-}
-
-# This loop generates rules to copy libraries to lib/
-foreach(library, _full_sdk_libraries) {
-  copy_tree("copy_${library}_library") {
-    visibility = [
-      ":copy_platform_sdk_libraries",
-      ":copy_full_sdk_libraries",
-    ]
-    source = "lib/$library"
-    dest = "$root_out_dir/dart-sdk/lib/$library"
-    exclude = "*.svn,doc,*.py,*.gypi,*.sh,.gitignore"
-  }
-}
-
 # This is the main rule to copy libraries in _platform_sdk_libraries to lib/
 group("copy_platform_sdk_libraries") {
   visibility = [
@@ -624,19 +658,6 @@ group("copy_libraries") {
   }
 }
 
-if (is_win) {
-  copy_tree("copy_7zip") {
-    visibility = [ ":create_common_sdk" ]
-    deps = [
-      ":copy_libraries",
-      ":copy_pub_assets",
-    ]
-    source = "../third_party/7zip"
-    dest = "$root_out_dir/dart-sdk/lib/_internal/pub/asset/7zip"
-    exclude = ".svn"
-  }
-}
-
 # This rule writes the version file.
 action("write_version_file") {
   visibility = [ ":create_common_sdk" ]