From 174ae059cce33116c04c61dc885e6e5b250eb19f Mon Sep 17 00:00:00 2001
From: Colin Cross <ccross@android.com>
Date: Tue, 3 Mar 2015 17:37:03 -0800
Subject: [PATCH] Report variant errors instead of panicing

Variant errors can be introduced by Blueprints files, so print
a module error instead of panicing.
---
 context.go    | 25 +++++++++++++++++++------
 module_ctx.go |  5 ++++-
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/context.go b/context.go
index 9fea1db..9ab359a 100644
--- a/context.go
+++ b/context.go
@@ -655,12 +655,14 @@ func (c *Context) processSubdirs(
 }
 
 func (c *Context) createVariants(origModule *moduleInfo, mutatorName string,
-	variantNames []string) []*moduleInfo {
+	variantNames []string) ([]*moduleInfo, []error) {
 
 	newModules := []*moduleInfo{}
 	origVariantName := origModule.name
 	group := origModule.group
 
+	var errs []error
+
 	for i, variantName := range variantNames {
 		typeName := group.typeName
 		factory, ok := c.moduleFactories[typeName]
@@ -713,7 +715,10 @@ func (c *Context) createVariants(origModule *moduleInfo, mutatorName string,
 		newModules = append(newModules, newModule)
 		c.moduleInfo[newModule.logicModule] = newModule
 
-		c.convertDepsToVariant(newModule, newSubName)
+		newErrs := c.convertDepsToVariant(newModule, newSubName)
+		if len(newErrs) > 0 {
+			errs = append(errs, newErrs...)
+		}
 	}
 
 	// Mark original variant as invalid.  Modules that depend on this module will still
@@ -721,10 +726,11 @@ func (c *Context) createVariants(origModule *moduleInfo, mutatorName string,
 	origModule.logicModule = nil
 	origModule.splitModules = newModules
 
-	return newModules
+	return newModules, errs
 }
 
-func (c *Context) convertDepsToVariant(module *moduleInfo, newSubName subName) {
+func (c *Context) convertDepsToVariant(module *moduleInfo, newSubName subName) (errs []error) {
+
 	for i, dep := range module.directDeps {
 		if dep.logicModule == nil {
 			var newDep *moduleInfo
@@ -735,12 +741,19 @@ func (c *Context) convertDepsToVariant(module *moduleInfo, newSubName subName) {
 				}
 			}
 			if newDep == nil {
-				panic(fmt.Sprintf("failed to find variant %s for module %s needed by %s",
-					newSubName.variantName, dep.group.properties.Name, module.group.properties.Name))
+				errs = append(errs, &Error{
+					Err: fmt.Errorf("failed to find variant %q for module %q needed by %q",
+						newSubName.variantName, dep.group.properties.Name,
+						module.group.properties.Name),
+					Pos: module.group.pos,
+				})
+				continue
 			}
 			module.directDeps[i] = newDep
 		}
 	}
+
+	return errs
 }
 
 func (c *Context) processModuleDef(moduleDef *parser.Module,
diff --git a/module_ctx.go b/module_ctx.go
index 4931b6d..4f65a8d 100644
--- a/module_ctx.go
+++ b/module_ctx.go
@@ -367,7 +367,10 @@ type BottomUpMutator func(mctx BottomUpMutatorContext)
 // automatically be updated to point to the first variant.
 func (mctx *mutatorContext) CreateVariants(variantNames ...string) []Module {
 	ret := []Module{}
-	modules := mctx.context.createVariants(mctx.module, mctx.name, variantNames)
+	modules, errs := mctx.context.createVariants(mctx.module, mctx.name, variantNames)
+	if len(errs) > 0 {
+		mctx.errs = append(mctx.errs, errs...)
+	}
 
 	for _, module := range modules {
 		ret = append(ret, module.logicModule)