Use ContainsProperty to support default values

Instead of setting a string property to magic default value and then
checking for it later, call ctx.ContainsProperty to determine if it
was set.  Use the same method on the clang bool property, which
couldn't be set to a magic value.

blueprint's ModuleContext.ContainsProperty only works on a single
property, not on all arch variant properties -
ModuleContext.ContainsProperty("clang") will return false if
clang was not set but arch.arm.clang was set - so track which
properties were extended inside extendProperties, and override
ModuleContext.ContainsProperty in AndroidModuleContext to also
check the extended properties.

Change-Id: I03cbe71dc69344972e23d6c794da9be05e720c45

1 files changed, 4 insertions, 10 deletions

diff --git a/cc/cc.go b/cc/cc.go
index e209faa0..d400df08 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -401,8 +401,7 @@ func (c *ccBase) collectFlags(ctx common.AndroidModuleContext, toolchain Toolcha
 	// TODO: debug
 	flags.CFlags = append(flags.CFlags, c.properties.Release.Cflags...)
 
-	if ctx.Host() {
-		// TODO: allow per-module clang disable for host
+	if ctx.Host() && !ctx.ContainsProperty("clang") {
 		flags.Clang = true
 	}
 
@@ -684,19 +683,15 @@ type ccLinked struct {
 func newCCDynamic(dynamic *ccLinked, module CCModuleType, hod common.HostOrDeviceSupported,
 	multilib common.Multilib, props ...interface{}) (blueprint.Module, []interface{}) {
 
-	dynamic.properties.System_shared_libs = []string{defaultSystemSharedLibraries}
-
 	props = append(props, &dynamic.dynamicProperties)
 
 	return newCCBase(&dynamic.ccBase, module, hod, multilib, props...)
 }
 
-const defaultSystemSharedLibraries = "__default__"
-
 func (c *ccLinked) systemSharedLibs(ctx common.AndroidBaseContext) []string {
-	if len(c.properties.System_shared_libs) == 1 &&
-		c.properties.System_shared_libs[0] == defaultSystemSharedLibraries {
-
+	if ctx.ContainsProperty("system_shared_libs") {
+		return c.properties.System_shared_libs
+	} else {
 		if ctx.Host() {
 			return []string{}
 		} else if c.properties.Sdk_version != "" {
@@ -714,7 +709,6 @@ func (c *ccLinked) systemSharedLibs(ctx common.AndroidBaseContext) []string {
 			return []string{"libc", "libm"}
 		}
 	}
-	return c.properties.System_shared_libs
 }
 
 func (c *ccLinked) stl(ctx common.AndroidBaseContext) string {