Merge "Propagate empty vs unspecified system_shared_libs correctly."

cc/binary_sdk_member.go

@@ -18,6 +18,7 @@ import (
 	"path/filepath"
 
 	"android/soong/android"
+
 	"github.com/google/blueprint"
 )
 
@@ -137,7 +138,9 @@ func (p *nativeBinaryInfoProperties) AddToPropertySet(ctx android.SdkMemberConte
 		propertySet.AddPropertyWithTag("shared_libs", p.SharedLibs, builder.SdkMemberReferencePropertyTag(false))
 	}
 
-	if len(p.SystemSharedLibs) > 0 {
+	// SystemSharedLibs needs to be propagated if it's a list, even if it's empty,
+	// so check for non-nil instead of nonzero length.
+	if p.SystemSharedLibs != nil {
 		propertySet.AddPropertyWithTag("system_shared_libs", p.SystemSharedLibs, builder.SdkMemberReferencePropertyTag(false))
 	}
 }

cc/cc.go

@@ -378,7 +378,7 @@ type linker interface {
 
 type specifiedDeps struct {
 	sharedLibs       []string
-	systemSharedLibs []string
+	systemSharedLibs []string // Note nil and [] are semantically distinct.
 }
 
 type installer interface {

cc/library.go

@@ -749,10 +749,12 @@ func (library *libraryDecorator) compilerDeps(ctx DepsContext, deps Deps) Deps {
 
 func (library *libraryDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
 	if library.static() {
+		// Compare with nil because an empty list needs to be propagated.
 		if library.StaticProperties.Static.System_shared_libs != nil {
 			library.baseLinker.Properties.System_shared_libs = library.StaticProperties.Static.System_shared_libs
 		}
 	} else if library.shared() {
+		// Compare with nil because an empty list needs to be propagated.
 		if library.SharedProperties.Shared.System_shared_libs != nil {
 			library.baseLinker.Properties.System_shared_libs = library.SharedProperties.Shared.System_shared_libs
 		}
@@ -828,10 +830,21 @@ func (library *libraryDecorator) linkerSpecifiedDeps(specifiedDeps specifiedDeps
 	}
 
 	specifiedDeps.sharedLibs = append(specifiedDeps.sharedLibs, properties.Shared_libs...)
-	specifiedDeps.systemSharedLibs = append(specifiedDeps.systemSharedLibs, properties.System_shared_libs...)
+
+	// Must distinguish nil and [] in system_shared_libs - ensure that [] in
+	// either input list doesn't come out as nil.
+	if specifiedDeps.systemSharedLibs == nil {
+		specifiedDeps.systemSharedLibs = properties.System_shared_libs
+	} else {
+		specifiedDeps.systemSharedLibs = append(specifiedDeps.systemSharedLibs, properties.System_shared_libs...)
+	}
 
 	specifiedDeps.sharedLibs = android.FirstUniqueStrings(specifiedDeps.sharedLibs)
-	specifiedDeps.systemSharedLibs = android.FirstUniqueStrings(specifiedDeps.systemSharedLibs)
+	if len(specifiedDeps.systemSharedLibs) > 0 {
+		// Skip this if systemSharedLibs is either nil or [], to ensure they are
+		// retained.
+		specifiedDeps.systemSharedLibs = android.FirstUniqueStrings(specifiedDeps.systemSharedLibs)
+	}
 	return specifiedDeps
 }
 
@@ -1371,6 +1384,8 @@ func reuseStaticLibrary(mctx android.BottomUpMutatorContext, static, shared *Mod
 			len(sharedCompiler.SharedProperties.Shared.Static_libs) == 0 &&
 			len(staticCompiler.StaticProperties.Static.Shared_libs) == 0 &&
 			len(sharedCompiler.SharedProperties.Shared.Shared_libs) == 0 &&
+			// Compare System_shared_libs properties with nil because empty lists are
+			// semantically significant for them.
 			staticCompiler.StaticProperties.Static.System_shared_libs == nil &&
 			sharedCompiler.SharedProperties.Shared.System_shared_libs == nil {
 

cc/library_sdk_member.go

@@ -212,7 +212,9 @@ func addPossiblyArchSpecificProperties(sdkModuleContext android.ModuleContext, b
 		outputProperties.AddPropertyWithTag("shared_libs", libInfo.SharedLibs, builder.SdkMemberReferencePropertyTag(false))
 	}
 
-	if len(libInfo.SystemSharedLibs) > 0 {
+	// SystemSharedLibs needs to be propagated if it's a list, even if it's empty,
+	// so check for non-nil instead of nonzero length.
+	if libInfo.SystemSharedLibs != nil {
 		outputProperties.AddPropertyWithTag("system_shared_libs", libInfo.SystemSharedLibs, builder.SdkMemberReferencePropertyTag(false))
 	}
 
@@ -327,7 +329,8 @@ type nativeLibInfoProperties struct {
 	// This field is exported as its contents may not be arch specific.
 	SharedLibs []string
 
-	// The set of system shared libraries
+	// The set of system shared libraries. Note nil and [] are semantically
+	// distinct - see BaseLinkerProperties.System_shared_libs.
 	//
 	// This field is exported as its contents may not be arch specific.
 	SystemSharedLibs []string

cc/linker.go

@@ -491,7 +491,15 @@ func (linker *baseLinker) link(ctx ModuleContext,
 
 func (linker *baseLinker) linkerSpecifiedDeps(specifiedDeps specifiedDeps) specifiedDeps {
 	specifiedDeps.sharedLibs = append(specifiedDeps.sharedLibs, linker.Properties.Shared_libs...)
-	specifiedDeps.systemSharedLibs = append(specifiedDeps.systemSharedLibs, linker.Properties.System_shared_libs...)
+
+	// Must distinguish nil and [] in system_shared_libs - ensure that [] in
+	// either input list doesn't come out as nil.
+	if specifiedDeps.systemSharedLibs == nil {
+		specifiedDeps.systemSharedLibs = linker.Properties.System_shared_libs
+	} else {
+		specifiedDeps.systemSharedLibs = append(specifiedDeps.systemSharedLibs, linker.Properties.System_shared_libs...)
+	}
+
 	return specifiedDeps
 }