[tests][intro] Add test for simlauncher [weak] frameworks. Fixes #6951 (#6957)

We ship a default, pre-built, simlauncher for iOS simulator applications.
This speeds up compilation for the default (non linked) simulator builds
quite a lot (no call to `clang` is needed). However it force us to keep
track of frameworks manually - `mtouch` can track them but requires
calling clang/ld to finish things up (killing the optimization).

It's easy to forget some (new) frameworks since they can be loaded
dynamically (on demand) _most_ of the time. Sadly there are a few cases
where doing so cause (hard to diagnose) problems - so we can't depend
on them being loaded, correctly for us.

The new test case loads the `otool -L` output (make when we build
simlauncher[32|64]-sgen) and compares it with mtouch's GetFramework
logic *and* with our namespaces (which is pretty close, with a few
exceptions, to the framework names). This will make it harder to
forget [weak] frameworks when adding new bindings :)

Fixes https://github.com/xamarin/xamarin-macios/issues/6951

tests/introspection/ApiFrameworkTest.cs

@@ -1,6 +1,7 @@
 #if __UNIFIED__
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Reflection;
 
 using NUnit.Framework;
@@ -137,6 +138,67 @@ namespace Introspection {
 			}
 			AssertIfErrors ($"{Errors} unknown frameworks found:\n{ErrorData}");
 		}
+
+#if __IOS__
+		[Test]
+		public void Simlauncher ()
+		{
+			if (Runtime.Arch != Arch.SIMULATOR)
+				Assert.Ignore ("Only needed on simulator");
+
+			var all = GetFrameworks ();
+
+			var namespaces = new HashSet<string> (StringComparer.OrdinalIgnoreCase);
+			foreach (Type t in Assembly.GetTypes ()) {
+				if (!t.IsPublic)
+					continue;
+				namespaces.Add (t.Namespace);
+			}
+
+			foreach (var line in File.ReadAllLines ("simlauncher64-sgen.frameworks")) {
+				var c = line.IndexOf (" (compatibility");
+				if (c < 0)
+					continue;
+				var path = line.Substring (1, c - 1);
+				if (!path.StartsWith ("/System/Library/Frameworks/", StringComparison.Ordinal))
+					continue;
+				var fx = Path.GetFileNameWithoutExtension (path);
+
+				// match with mtouch framework list
+				if (!all.TryGetValue (fx, out var framework)) {
+					// special cases
+					switch (fx) {
+					case "CoreAudio": // AudioToolbox, AVFoundation...
+					case "CoreFoundation": // implied (always linked)
+					case "CFNetwork": // implied (StartWWAN) and included (mostly) in CoreServices
+					case "OpenAL": // part of OpenTK
+						break;
+					case "CoreMIDI":
+						// CoreMidi (case) in the fx list
+						break;
+					default:
+						ReportError ($"{fx} is not part of mtouch's GetFrameworks");
+						break;
+					}
+				}
+
+				// match with Xamarin.iOS.dll namespaces
+				if (!namespaces.Contains (fx)) {
+					// special cases
+					switch (fx) {
+					case "CoreAudio": // AudioToolbox, AVFoundation...
+					case "CFNetwork": // implied (StartWWAN) and included (mostly) in CoreServices
+					case "OpenAL": // part of OpenTK
+						break;
+					default:
+						ReportError ($"{fx} is not part of mtouch's GetFrameworks");
+						break;
+					}
+				}
+
+			}
+		}
+#endif
 	}
 }
 #endif

tests/introspection/iOS/introspection-ios.csproj

@@ -248,6 +248,9 @@
     <BundleResource Include="..\xamarin1.png">
       <Link>xamarin1.png</Link>
     </BundleResource>
+    <BundleResource Include="..\..\..\tools\mtouch\simlauncher64-sgen.frameworks">
+      <Link>simlauncher64-sgen.frameworks</Link>
+    </BundleResource>
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath)\Xamarin\iOS\Xamarin.iOS.CSharp.targets" />
 </Project>

tools/mtouch/.gitignore

@@ -9,4 +9,4 @@ simlauncher32-sgen
 simlauncher64-sgen
 *.stamp
 mtouch.csproj.inc
-
+*.frameworks

tools/mtouch/Makefile

@@ -60,7 +60,6 @@ SIMLAUNCHER_FRAMEWORKS =  \
 	-framework CoreText			\
 	-framework ExternalAccessory		\
 	-framework GameKit				\
-	-framework IOKit			\
 	-framework MapKit			\
 	-framework MediaPlayer			\
 	-framework MessageUI			\
@@ -184,7 +183,7 @@ simlauncher$(5)$(1): simlauncher.m $(TOP)/runtime/.libs/ios/libxamarin.a $(BUILD
 		$(TOP)/runtime/.libs/ios/libapp.a \
 		-Wl,-w \
 		-lz -liconv $(TOP)/runtime/.libs/ios/libxamarin-debug.a simlauncher.m $(SIMLAUNCHER_FRAMEWORKS) $(SIMULATOR$(4)_OBJC_CFLAGS) -o $$@
-
+	$(Q) xcrun otool -L simlauncher$(5)$(1) > simlauncher$(5)$(1).frameworks
 endef
 
 $(eval $(call SimlauncherTemplate,-sgen,$(BUILD_DESTDIR)/simulator86/lib/libmono-profiler-log.a -u _mono_profiler_init_log -DXAMCORE_2_0 Xamarin.iOS.registrar.ios.a,sgen,86,32))