feat($injector): print caller name in "unknown provider" errors (when available)

Fixes angular#8135

Author: ocombe

src/auto/injector.js

@@ -176,6 +176,7 @@ function annotate(fn, strictDi, name) {
  * Return an instance of the service.
  *
  * @param {string} name The name of the instance to retrieve.
+ * @param {string} caller The origin of the function call, only used to provide more background in error messages.
  * @return {*} The instance.
  */
 
@@ -622,14 +623,17 @@ function createInjector(modulesToLoad, strictDi) {
           }
       },
       providerInjector = (providerCache.$injector =
-          createInternalInjector(providerCache, function() {
+          createInternalInjector(providerCache, function(serviceName, caller) {
+            if (angular.isString(caller)) {
+              path.push(caller);
+            }
             throw $injectorMinErr('unpr', "Unknown provider: {0}", path.join(' <- '));
           })),
       instanceCache = {},
       instanceInjector = (instanceCache.$injector =
-          createInternalInjector(instanceCache, function(servicename) {
-            var provider = providerInjector.get(servicename + providerSuffix);
-            return instanceInjector.invoke(provider.$get, provider, undefined, servicename);
+          createInternalInjector(instanceCache, function(serviceName, caller) {
+            var provider = providerInjector.get(serviceName + providerSuffix, caller);
+            return instanceInjector.invoke(provider.$get, provider, undefined, serviceName);
           }));
 
 
@@ -759,7 +763,7 @@ function createInjector(modulesToLoad, strictDi) {
 
   function createInternalInjector(cache, factory) {
 
-    function getService(serviceName) {
+    function getService(serviceName, caller) {
       if (cache.hasOwnProperty(serviceName)) {
         if (cache[serviceName] === INSTANTIATING) {
           throw $injectorMinErr('cdep', 'Circular dependency found: {0}',
@@ -770,7 +774,7 @@ function createInjector(modulesToLoad, strictDi) {
         try {
           path.unshift(serviceName);
           cache[serviceName] = INSTANTIATING;
-          return cache[serviceName] = factory(serviceName);
+          return cache[serviceName] = factory(serviceName, caller);
         } catch (err) {
           if (cache[serviceName] === INSTANTIATING) {
             delete cache[serviceName];
@@ -802,7 +806,7 @@ function createInjector(modulesToLoad, strictDi) {
         args.push(
           locals && locals.hasOwnProperty(key)
           ? locals[key]
-          : getService(key)
+          : getService(key, serviceName)
         );
       }
       if (isArray(fn)) {