# HG changeset patch
# User Mike Shal <mshal@mozilla.com>
# Date 1526333421 14400
#      Mon May 14 17:30:21 2018 -0400
# Node ID d90a5a4aab56b989e8780970ede900dd39916535
# Parent  a6c147f96297b8d200a64ac1bec2d18cd784bfd9
Bug 1461795 - Use FileAvoidWrite when writing mozinfo.json; r=chmanchester

Since MozbuildObject.from_environment() reads from mozinfo.json, tup
picks up that file as a dependency for anything that imports buildconfig
(eg: all generated files). Using FileAvoidWrite when creating
mozinfo.json will help avoid unnecessary work after re-running configure
in the tup backend.

MozReview-Commit-ID: EEOPQYJA1MV

diff --git a/configure.py b/configure.py
--- a/configure.py
+++ b/configure.py
@@ -103,17 +103,16 @@ def config_status(config):
                                                                config['TOPSRCDIR'])))
     with open('configure.d', 'w') as fh:
         mk.dump(fh)
 
     # Other things than us are going to run this file, so we need to give it
     # executable permissions.
     os.chmod('config.status', 0o755)
     if config.get('MOZ_BUILD_APP') != 'js' or config.get('JS_STANDALONE'):
-        os.environ[b'WRITE_MOZINFO'] = b'1'
         from mozbuild.config_status import config_status
 
         # Some values in sanitized_config also have more complex types, such as
         # EnumString, which using when calling config_status would currently
         # break the build, as well as making it inconsistent with re-running
         # config.status. Fortunately, EnumString derives from unicode, so it's
         # covered by converting unicode strings.
 
diff --git a/python/mozbuild/mozbuild/config_status.py b/python/mozbuild/mozbuild/config_status.py
--- a/python/mozbuild/mozbuild/config_status.py
+++ b/python/mozbuild/mozbuild/config_status.py
@@ -17,16 +17,17 @@ import time
 from argparse import ArgumentParser
 
 from mach.logging import LoggingManager
 from mozbuild.backend.configenvironment import ConfigEnvironment
 from mozbuild.base import MachCommandConditions
 from mozbuild.frontend.emitter import TreeMetadataEmitter
 from mozbuild.frontend.reader import BuildReader
 from mozbuild.mozinfo import write_mozinfo
+from mozbuild.util import FileAvoidWrite
 from itertools import chain
 
 from mozbuild.backend import (
     backends,
     get_backend_class,
 )
 
 
@@ -109,20 +110,18 @@ def config_status(topobjdir='.', topsrcd
     # Without -n, the current directory is meant to be the top object directory
     if not options.not_topobjdir:
         topobjdir = os.path.abspath('.')
 
     env = ConfigEnvironment(topsrcdir, topobjdir, defines=defines,
             non_global_defines=non_global_defines, substs=substs,
             source=source, mozconfig=mozconfig)
 
-    # mozinfo.json only needs written if configure changes and configure always
-    # passes this environment variable.
-    if 'WRITE_MOZINFO' in os.environ:
-        write_mozinfo(os.path.join(topobjdir, 'mozinfo.json'), env, os.environ)
+    with FileAvoidWrite(os.path.join(topobjdir, 'mozinfo.json')) as f:
+        write_mozinfo(f, env, os.environ)
 
     cpu_start = time.clock()
     time_start = time.time()
 
     # Make appropriate backend instances, defaulting to RecursiveMakeBackend,
     # or what is in BUILD_BACKENDS.
     selected_backends = [get_backend_class(b)(env) for b in options.backend]