Remove a stateful workaround for ResultBuilders.

In an earlier version of the ASTScope -> SILdebugScope translation a wrokaround
was put into place that would select the current debug scope if an ASTScope was
marked as ignoreInDebugInfo. Removing this workaround makes the translation more
predictable as it eliminated the dependency on the current SILBuilder state. The
result builder tests still pass without this.

rdar://108736443

Author: adrian-prantl

lib/SILGen/SILGenFunction.cpp

@@ -370,20 +370,9 @@ SILGenFunction::getOrCreateScope(const ast_scope::ASTScopeImpl *ASTScope,
   // Decide whether to pick a parent scope instead.
   if (ASTScope->ignoreInDebugInfo()) {
     LLVM_DEBUG(llvm::dbgs() << "ignored\n");
-    // FIXME: it would be more deterministic to use
-    //        getOrCreateScope(ASTScope->getParent().getPtrOrNull());
-    //        here. Unfortunately property wrappers rearrange AST
-    //        nodes without marking them as implicit, e.g.:
-    //
-    //           @Wrapper(a) var v = b
-    //        ->
-    //           let _tmp = Constructor(a, b); var v = _tmp
-    //
-    //        Since the arguments to Constructor aren't marked as implicit,
-    //        argument b is in the scope of v, but the call to Constructor
-    //        isn't, which correctly triggers the scope hole verifier.
-    auto *CurScope = B.getCurrentDebugScope();
-    return CurScope->InlinedCallSite != InlinedAt ? FnScope : CurScope;
+    auto *ParentScope = getOrCreateScope(ASTScope->getParent().getPtrOrNull(),
+                                         FnScope, InlinedAt);
+    return ParentScope->InlinedCallSite != InlinedAt ? FnScope : ParentScope;
   }
 
   // Collapse BraceStmtScopes whose parent is a .*BodyScope.

test/DebugInfo/guard-let-scope3.swift

@@ -0,0 +1,19 @@
+// RUN: %target-swift-frontend -g -emit-sil %s -parse-as-library -module-name a | %FileCheck %s
+public class C {}
+public enum MyError : Error {
+  init() { self.init() }
+}
+public class S {
+  private var c = [Int : C?]()
+  public func f(_ i: Int) throws  -> C {
+    guard let x = c[i], let x else {
+    // CHECK: sil_scope [[X1:[0-9]+]] { loc "{{.*}}":[[@LINE-1]]:5
+    // CHECK: sil_scope [[X2:[0-9]+]] { loc "{{.*}}":[[@LINE-2]]:29
+    // CHECK: debug_value {{.*}} : $Optional<C>, let, name "x", {{.*}}, scope [[X1]]
+    // CHECK: debug_value %29 : $C, let, name "x", {{.*}}, scope [[X2]]
+    // CHECK-NEXT:  scope [[X2]]
+      throw MyError()
+    }
+    return x
+  }
+}