gn format: Support # NOSORT to disable sorting of blocks

R=brettw@chromium.org
BUG=591953

Review URL: https://codereview.chromium.org/1766163002

Cr-Original-Commit-Position: refs/heads/master@{#380709}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: aa7f7d038156bdf3f317773b784b4a308efd0132

tools/gn/command_format.cc

diff --git a/tools/gn/command_format.cc b/tools/gn/command_format.cc
index d7301c9..ae36e37 100644
--- a/tools/gn/command_format.cc
+++ b/tools/gn/command_format.cc
@@ -35,6 +35,16 @@
     "\n"
     "  Formats .gn file to a standard format.\n"
     "\n"
+    "  The contents of some lists ('sources', 'deps', etc.) will be sorted to\n"
+    "  a canonical order. To suppress this, you can add a comment of the form\n"
+    "  \"# NOSORT\" immediately preceeding the assignment. e.g.\n"
+    "\n"
+    "  # NOSORT\n"
+    "  sources = [\n"
+    "    \"z.cc\",\n"
+    "    \"a.cc\",\n"
+    "  ]\n"
+    "\n"
     "Arguments\n"
     "  --dry-run\n"
     "      Does not change or output anything, but sets the process exit code\n"
@@ -315,6 +325,12 @@
 }
 
 void Printer::SortIfSourcesOrDeps(const BinaryOpNode* binop) {
+  if (binop && binop->comments() && !binop->comments()->before().empty() &&
+      binop->comments()->before()[0].value().as_string() == "# NOSORT") {
+    // Allow disabling of sort for specific actions that might be
+    // order-sensitive.
+    return;
+  }
   const IdentifierNode* ident = binop->left()->AsIdentifier();
   const ListNode* list = binop->right()->AsList();
   if ((binop->op().value() == "=" || binop->op().value() == "+=" ||

tools/gn/command_format_unittest.cc

diff --git a/tools/gn/command_format_unittest.cc b/tools/gn/command_format_unittest.cc
index 8e8c256..7c79d41 100644
--- a/tools/gn/command_format_unittest.cc
+++ b/tools/gn/command_format_unittest.cc
@@ -103,3 +103,4 @@
 FORMAT_TEST(063)
 FORMAT_TEST(064)
 FORMAT_TEST(065)
+FORMAT_TEST(066)

tools/gn/format_test_data/066.gn

diff --git a/tools/gn/format_test_data/066.gn b/tools/gn/format_test_data/066.gn
new file mode 100644
index 0000000..c62eb2a
--- /dev/null
+++ b/tools/gn/format_test_data/066.gn
@@ -0,0 +1,30 @@
+# Suppress sorting based on comment.
+
+# NOSORT
+sources = []
+
+# NOSORT
+sources = [
+  "a",
+]
+
+# NOSORT
+sources += [
+  "a",
+]
+
+# NOSORT
+sources = [
+  "z",
+  "z2",
+  "a",
+  "y.cc",
+]
+
+# NOSORT
+sources += [
+  "z",
+  "z2",
+  "a",
+  "y.cc",
+]

tools/gn/format_test_data/066.golden

diff --git a/tools/gn/format_test_data/066.golden b/tools/gn/format_test_data/066.golden
new file mode 100644
index 0000000..45467b8
--- /dev/null
+++ b/tools/gn/format_test_data/066.golden
@@ -0,0 +1,28 @@
+# Suppress sorting based on comment.
+
+# NOSORT
+sources = []
+
+# NOSORT
+sources = [
+  "a",
+]
+
+# NOSORT
+sources += [ "a" ]
+
+# NOSORT
+sources = [
+  "z",
+  "z2",
+  "a",
+  "y.cc",
+]
+
+# NOSORT
+sources += [
+  "z",
+  "z2",
+  "a",
+  "y.cc",
+]