Fix crash with runtime enabled on Windows, this one was due to Except…

…ion traversing runtime boundaries.

`runtimeSection` now only support `nothrow` callees.

core/dplug/core/runtime.d

@@ -67,25 +67,14 @@ auto runtimeSection(F)(F functionOrDelegateThatCanBeGC) nothrow @nogc if (isCall
     auto myGCDelegate = toDelegate(functionOrDelegateThatCanBeGC);
     alias T = typeof(myGCDelegate);
 
-    static ReturnType!T internalFunc(T fun, Parameters!T params)
+    static ReturnType!T internalFunc(T fun, Parameters!T params) nothrow
     {
         import core.stdc.stdio;
         ScopedRuntimeSection section;
+        section.enter();
 
-        try
-        {
-            section.enter();
-        }
-        catch(Exception e)
-        {
-            // runtime initialization failed
-            // this should never happen
-            assert(false);
-        }
-
-        // the nice thing here is that `nothrow` is inferred so GC created Exception 
-        // will traverse the boundaries, albeit collected...
-        // TODO if fun can throw, convert the exception to manually handled Exception and strings
+        // Important: we only support `nothrow` runtime section.
+        // Supporting exception was creating spurious bugs, probably the excpeption being collected.
         return fun(params);
     }      
 
@@ -96,7 +85,7 @@ auto runtimeSection(F)(F functionOrDelegateThatCanBeGC) nothrow @nogc if (isCall
         typeof(myGCDelegate.ptr) ptr;
         typeof(myGCDelegate.funcptr) funcptr;
 
-        ReturnType!T opCall(Parameters!T params) @nogc
+        ReturnType!T opCall(Parameters!T params) nothrow @nogc
         {
             T dg;
             dg.funcptr = funcptr;

tests/using-runtime/main.d

@@ -102,19 +102,9 @@ nothrow:
         assert(result == 1984);
 
         // You can call stand-alone functions or methods
-        try
-        {
-            size_t len = runtimeSection(&myCarelessFunction)(false);
-            assert(len == 4000);
-            len = runtimeSection(&myCarelessFunction)(true);
-        }
-        catch(Exception e)
-        {
-            // for some reason the Exception allocated in the runtime section hasn't been 
-            // collected, not sure why
-            // Anyway it's UB to read it and I'm not sure you can really catch it in the first place.
-            //printf("%s\n", e.msg.ptr);
-        }
+        // but they have to be `nothrow`.
+        size_t len = runtimeSection(&myCarelessFunction)();
+        assert(len == 4000);
     }
 
     override void processAudio(const(float*)[] inputs, float*[]outputs, int frames, TimeInfo info)
@@ -160,12 +150,9 @@ static void cleanupObject(ref HeapObject obj) nothrow
     }
 }
 
-size_t myCarelessFunction(bool doThrow)
+size_t myCarelessFunction() nothrow
 {
     auto A = new ubyte[4000];
-    if (doThrow)
-        throw new Exception("an error!");
-    else
-        return A.length;
+    return A.length;
 }