Send Bazel startup options to server.

Send the startup options tagged with their origin so that the server has correct information about the command line as the client received it.

Removes the unconditional stderr printing of all bazelrc startup options in the bazel client. Instead, the startup options are sent to the server and the same informational printing is gated on the --announce_rc option. This avoids unconditional log spam to stderr early in startup. If the server is unreachable or there are errors parsing startup options, the message is still printed to stderr.

Fixes https://github.com/bazelbuild/bazel/issues/2530.

RELNOTES: --announce_rc now controls whether bazelrc startup options are printed to stderr.
PiperOrigin-RevId: 165211007

src/main/cpp/option_processor.cc

diff --git a/src/main/cpp/option_processor.cc b/src/main/cpp/option_processor.cc
index b3b4afa..325e8ce 100644
--- a/src/main/cpp/option_processor.cc
+++ b/src/main/cpp/option_processor.cc
@@ -86,7 +86,6 @@
   // A '\' at the end of a line continues the line.
   blaze_util::Replace("\\\r\n", "", &contents);
   blaze_util::Replace("\\\n", "", &contents);
-  vector<string> startup_options;
 
   vector<string> lines = blaze_util::Split(contents, '\n');
   for (string& line : lines) {
@@ -153,19 +152,10 @@
       words_it++;  // Advance past command.
       for (; words_it != words.end(); words_it++) {
         (*rcoptions)[command].push_back(RcOption(index, *words_it));
-        if (command == "startup") {
-          startup_options.push_back(*words_it);
-        }
       }
     }
   }
 
-  if (!startup_options.empty()) {
-    string startup_args;
-    blaze_util::JoinStrings(startup_options, ' ', &startup_args);
-    fprintf(stderr, "INFO: Reading 'startup' options from %s: %s\n",
-            filename.c_str(), startup_args.c_str());
-  }
   return blaze_exit_code::SUCCESS;
 }
 
@@ -389,8 +379,50 @@
   return blaze_exit_code::SUCCESS;
 }
 
+static void PrintStartupOptions(const std::string& source,
+                                const std::vector<std::string>& options) {
+  if (!source.empty()) {
+    std::string startup_args;
+    blaze_util::JoinStrings(options, ' ', &startup_args);
+    fprintf(stderr, "INFO: Reading 'startup' options from %s: %s\n",
+            source.c_str(), startup_args.c_str());
+  }
+}
+
+void OptionProcessor::PrintStartupOptionsProvenanceMessage() const {
+  StartupOptions* parsed_startup_options = GetParsedStartupOptions();
+
+  // Print the startup flags in the order they are parsed, to keep the
+  // precendence clear. In order to minimize the number of lines of output in
+  // the terminal, group sequential flags by origin. Note that an rc file may
+  // turn up multiple times in this list, if, for example, it imports another
+  // rc file and contains startup options on either side of the import
+  // statement. This is done intentionally to make option priority clear.
+  std::string command_line_source;
+  std::string& most_recent_blazerc = command_line_source;
+  std::vector<std::string> accumulated_options;
+  for (auto flag : parsed_startup_options->original_startup_options_) {
+    if (flag.source == most_recent_blazerc) {
+      accumulated_options.push_back(flag.value);
+    } else {
+      PrintStartupOptions(most_recent_blazerc, accumulated_options);
+      // Start accumulating again.
+      accumulated_options.clear();
+      accumulated_options.push_back(flag.value);
+      most_recent_blazerc = flag.source;
+    }
+  }
+  // Don't forget to print out the last ones.
+  PrintStartupOptions(most_recent_blazerc, accumulated_options);
+}
+
 blaze_exit_code::ExitCode OptionProcessor::ParseStartupOptions(
     std::string *error) {
+  // Rc files can import other files at any point, and these imported rcs are
+  // expanded in place. The effective ordering of rc flags is stored in
+  // rcoptions_ and should be processed in that order. Here, we isolate just the
+  // startup options, but keep the file they came from attached for the
+  // option_sources tracking and for sending to the server.
   std::vector<RcStartupFlag> rcstartup_flags;
 
   auto iter = rcoptions_.find("startup");
@@ -482,8 +514,8 @@
     result.push_back("--rc_source=" + blaze::ConvertPath(blazerc->Filename()));
   }
 
-  // Process RcOptions exept for the startup flags that are already parsed
-  // by the client and shouldn't be handled by defult_overrides.
+  // Process RcOptions except for the startup flags that are already parsed
+  // by the client and shouldn't be included in the command args.
   for (auto it = rcoptions.begin(); it != rcoptions.end(); ++it) {
     if (it->first != "startup") {
       for (const RcOption& rcoption : it->second) {