[silgen] If SILVerifyAll is enabled verify the body of thunks in buildThunkBody.

This just ensures that all thunks are verified right when they are created. This
is necessary since some thunks do not go through function post processing.

Author: gottesmm

lib/SILGen/SILGenPoly.cpp

@@ -95,6 +95,7 @@
 #include "Scope.h"
 #include "TupleGenerators.h"
 #include "swift/Basic/Assertions.h"
+#include "swift/Basic/Defer.h"
 #include "swift/Basic/Generators.h"
 #include "swift/AST/ASTMangler.h"
 #include "swift/AST/ConformanceLookup.h"
@@ -5400,6 +5401,11 @@ static void buildThunkBody(SILGenFunction &SGF, SILLocation loc,
   PrettyStackTraceSILFunction stackTrace("emitting reabstraction thunk in",
                                          &SGF.F);
   auto thunkType = SGF.F.getLoweredFunctionType();
+  SWIFT_DEFER {
+    // If verify all is enabled, verify thunk bodies.
+    if (SGF.getASTContext().SILOpts.VerifyAll)
+      SGF.F.verify();
+  };
 
   FullExpr scope(SGF.Cleanups, CleanupLocation(loc));