Simplify @path handling

- Lay the ground to make @rootPathAttribute as the default by deprecating unattributed interfaces.
- Kill RootPathAttribute and use PathAttribute only instead: There was no real difference between @rootpath and @path, as they were mutually exclusive (path on method, rootPath on interface) and had the same behavior (e.g. they are always relative). This will obviously make user code less error-prone.
- Communicate the settings to the sub-interface.

examples/rest/source/app.d

@@ -154,6 +154,7 @@ interface Example3API
 	int getMyID(int id);
 }
 
+@path("/")
 interface Example3APINested
 {
 	/* In this example it will be available under "GET /nested_module/number"

source/vibe/web/common.d

@@ -322,19 +322,20 @@ PathAttribute path(string data)
 	UDA to define root URL prefix for annotated REST interface.
 	Empty path means deducing prefix from interface type name (see also rootPathFromName)
  */
-RootPathAttribute rootPath(string path)
+deprecated("rootPath is deprecated. Use path directly.")
+PathAttribute rootPath(string path)
 {
 	if (!__ctfe)
 		assert(false, onlyAsUda!__FUNCTION__);
-	return RootPathAttribute(path);
+	return PathAttribute(path);
 }
 ///
 unittest
 {
 	import vibe.http.router;
 	import vibe.web.rest;
 
-	@rootPath("/oops")
+	@path("/oops")
 	interface IAPI
 	{
 		int getFoo();
@@ -355,10 +356,16 @@ unittest
 	assert(routes[0].pattern == "/oops/foo" && routes[0].method == HTTPMethod.GET);
 }
 
-
 /**
-	Convenience alias
- */
+   Convenience alias
+
+   This alias will ultimately be deprecated and made the default.
+   In Vibe.d 0.7.23 and before, unattributed interface had a path of "/".
+   In Vibe.d 0.7.24, this is deprecated, and it won't compile with 0.7.25.
+   In 0.7.26, it's allowed again, but the default is to have the name
+   infered from the interface name -the same behavior that rootPathFromName
+   currently provide-.
+*/
 @property RootPathAttribute rootPathFromName()
 {
 	if (!__ctfe)

source/vibe/web/rest.d

@@ -79,14 +79,22 @@ void registerRestInterface(TImpl)(URLRouter router, TImpl instance, RestInterfac
 
 	string url_prefix = settings.baseURL.path.toString();
 
-	enum uda = findFirstUDA!(RootPathAttribute, I);
+	enum uda = findFirstUDA!(PathAttribute, I);
 	static if (uda.found) {
 		static if (uda.value.data == "") {
 			auto path = "/" ~ adjustMethodStyle(I.stringof, settings.methodStyle);
 			url_prefix = concatURL(url_prefix, path);
 		} else {
 			url_prefix = concatURL(url_prefix, uda.value.data);
 		}
+	} else {
+		pragma(msg, `Warning: Unattributed interface are deprecated and will error on the next release. Use @path("/") instead`);
+		// Warning introduced in 0.7.24. It will become an error on 0.7.25.
+		// On 0.7.26, it will be legal again, but with a different default (uncomment following code).
+		/*
+		  auto path = "/" ~ adjustMethodStyle(I.stringof, settings.methodStyle);
+		  url_prefix = concatURL(url_prefix, path);
+		*/
 	}
 
 	void addRoute(HTTPMethod httpVerb, string url, HTTPServerRequestDelegate handler, string[] params)
@@ -136,10 +144,12 @@ void registerRestInterface(TImpl)(URLRouter router, TImpl instance, RestInterfac
 					ParameterTypeTuple!overload.length == 0,
 					"Interfaces may only be returned from parameter-less functions!"
 				);
+				auto subSettings = settings.dup;
+				subSettings.baseURL = URL(concatURL(url_prefix, url, true));
 				registerRestInterface!RT(
 					router,
 					__traits(getMember, instance, method)(),
-					concatURL(url_prefix, url, true)
+					subSettings
 				);
 			} else {
 				// normal handler
@@ -294,13 +304,18 @@ class RestInterfaceClient(I) : I
 		}
 
 		URL url = settings.baseURL;
-		enum uda = findFirstUDA!(RootPathAttribute, I);
+		enum uda = findFirstUDA!(PathAttribute, I);
 		static if (uda.found) {
 			static if (uda.value.data == "") {
 				url.path = Path(concatURL(url.path.toString(), adjustMethodStyle(I.stringof, settings.methodStyle), true));
 			} else {
 				url.path = Path(concatURL(url.path.toString(), uda.value.data, true));
 			}
+		} else {
+			pragma(msg, `Warning: Unattributed interface are deprecated and will error on the next release. Use @path("/") instead`);
+			// Warning introduced in 0.7.24. It will become an error on 0.7.25.
+			// On 0.7.26, it will be legal again, but with a different default (uncomment following code).
+			//url.path = Path(concatURL(url.path.toString(), adjustMethodStyle(I.stringof, settings.methodStyle), true));
 		}
 
 		m_baseURL = url;