Bug 1249167 - Fix dependencies involving stdc++compat and clang-plugin. r=mshal

build/templates.mozbuild

@@ -90,11 +90,17 @@ def HostStdCppCompat():
 
 
 @template
-def HostProgram(name):
+def HostProgram(name, c_only=False):
     '''Template for build tools executables.'''
     HOST_PROGRAM = name
 
-    HostStdCppCompat()
+    # With context-based templates, this won't be needed anymore, and will
+    # work better than relying on the caller setting it, but at the moment,
+    # this is the best we have. And it doesn't matter /that/ much, so there's
+    # really only one place using this, where it does matter to avoid the
+    # extra dependency (because it creates a circular one).
+    if not c_only:
+        HostStdCppCompat()
 
 
 @template

config/moz.build

@@ -24,7 +24,10 @@ if CONFIG['HOST_OS_ARCH'] != 'WINNT':
         'nsinstall.c',
         'pathsub.c',
     ]
-    HostProgram('nsinstall_real')
+    # stdc++compat depends on config/export, so avoid a circular
+    # dependency added by HostProgram depending on stdc++compat,
+    # while the program here is in C.
+    HostProgram('nsinstall_real', c_only=True)
 
 if CONFIG['MOZ_SHARED_ICU']:
     DEFINES['MOZ_SHARED_ICU'] = True

config/recurse.mk

@@ -152,7 +152,7 @@ widget/android/bindings/export: build/annotationProcessors/export
 mobile/android/tests/browser/robocop/roboextender/tools: mobile/android/tests/javaaddons/tools
 
 ifdef ENABLE_CLANG_PLUGIN
-$(filter-out build/clang-plugin/%,$(compile_targets)): build/clang-plugin/target build/clang-plugin/tests/target
+$(filter-out config/host build/unix/stdc++compat/% build/clang-plugin/%,$(compile_targets)): build/clang-plugin/target build/clang-plugin/tests/target
 build/clang-plugin/tests/target: build/clang-plugin/target
 endif
 
@@ -176,3 +176,6 @@ endif
 # happen at the same time (bug #1146738)
 js/src/target: js/src/host
 endif
+# Most things are built during compile (target/host), but some things happen during export
+# Those need to depend on config/export for system wrappers.
+$(addprefix build/unix/stdc++compat/,target host) build/clang-plugin/target: config/export