In vector_gen, don't use .clang-format symlink

Instead copying or symlinking the `.clang-format` settings file into
place (which is problematic when writing to `bazel-genfiles`), instead
we now pass its contents on the command line.

.clang-format

@@ -3,9 +3,8 @@
 # This file determines clang-format's style settings; for details, refer to
 # http://clang.llvm.org/docs/ClangFormatStyleOptions.html
 
----
 BasedOnStyle:  Google
----
+
 Language: Cpp
 
 # Force pointers to the type for C++.
@@ -43,4 +42,4 @@ IncludeCategories:
   # Other libraries' h files (with quotes).
   - Regex:    '^"'
     Priority: 41
----
+

tools/vector_gen/lcm_vector_gen.py

@@ -6,6 +6,7 @@
 import collections
 import os
 import subprocess
+import yaml
 
 import google.protobuf.text_format
 
@@ -628,21 +629,16 @@ def generate_code(
                                                       field['doc']), 1)
             put(lcm, LCMTYPE_POSTAMBLE % context, 1)
 
-    # Run clang-format over all C++ files.
-    for one_filename in cxx_names:
-        # The clang-format tool has no way to specify a config file, other than
-        # putting a dotfile somehwere in a parent dir of the target.  Because
-        # our output is in genfiles but the dotfile is in runfiles, we won't
-        # automatically find it.  We'll resolve that by temporarily symlinking
-        # the dotfile into place.
-        dotfile = find_data(".clang-format")
-        temp_dotfile = os.path.join(
-            os.path.dirname(one_filename), ".clang-format")
-        assert not os.path.exists(temp_dotfile)
-        os.symlink(dotfile, temp_dotfile)
-        subprocess.check_call([
-            get_clang_format_path(), "--style=file", "-i", one_filename])
-        os.unlink(temp_dotfile)
+    # Run clang-format over all C++ files.  Instead copying the clang-format
+    # settings file into place (which is problematic when writing to
+    # bazel-genfiles), we pass its contents on the command line instead.
+    with open(find_data(".clang-format"), "r") as f:
+        yaml_data = yaml.load(f, Loader=yaml.Loader)
+        style = str(yaml_data)
+        # For some reason, clang-format really wants lowercase for booleans.
+        style = style.replace("False", "false").replace("True", "true")
+    subprocess.check_call([
+        get_clang_format_path(), "--style=" + style, "-i"] + cxx_names)
 
 
 def generate_all_code(srcs, outs):