Merge pull request #70160 from DougGregor/ast-verifier-thrown-error-contexts

Teach AST verifier about thrown error contexts

Author: DougGregor

include/swift/Basic/MacroRoles.def

@@ -13,6 +13,11 @@
 // This file defines all of the kinds of macro roles. Clients should define
 // either MACRO_ROLE or both ATTACHED_MACRO_ROLE and FREESTANDING_MACRO_ROLE.
 //
+// The order of the macro roles in this file is significant for the
+// serialization of module files. Please do not re-order the entries without
+// also bumping the module format version. When introducing new macro roles,
+// please add them to the end of the file.
+//
 //===----------------------------------------------------------------------===//
 
 #ifndef ATTACHED_MACRO_ROLE

lib/AST/ASTVerifier.cpp

@@ -28,6 +28,7 @@
 #include "swift/AST/Initializer.h"
 #include "swift/AST/MacroDiscriminatorContext.h"
 #include "swift/AST/Module.h"
+#include "swift/AST/NameLookup.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/Pattern.h"
 #include "swift/AST/PrettyStackTrace.h"
@@ -1021,13 +1022,22 @@ class Verifier : public ASTWalker {
 
     void verifyChecked(ThrowStmt *S) {
       Type thrownError;
-      if (!Functions.empty()) {
-        if (auto fn = AnyFunctionRef::fromDeclContext(Functions.back()))
-          thrownError = fn->getThrownErrorType();
+      SourceLoc loc = S->getThrowLoc();
+      if (loc.isValid()) {
+        auto catchNode = ASTScope::lookupCatchNode(getModuleContext(), loc);
+	if (catchNode) {
+          if (auto thrown = catchNode.getThrownErrorTypeInContext(Ctx)) {
+            thrownError = *thrown;
+          } else {
+            thrownError = Ctx.getNeverType();
+          }
+        } else {
+          thrownError = checkExceptionTypeExists("throw expression");
+        }
+      } else {
+        return;
       }
 
-      if (!thrownError)
-        thrownError = checkExceptionTypeExists("throw expression");
       checkSameType(S->getSubExpr()->getType(), thrownError, "throw operand");
       verifyCheckedBase(S);
     }

test/SILGen/typed_throws.swift

@@ -130,6 +130,23 @@ open class MyClass {
   func f() throws { }
 }
 
+
+struct Foo: Error { }
+struct Bar: Error { }
+
+// CHECK-LABEL: sil hidden [ossa] @$s12typed_throws0B22DifferentFromEnclosingyyAA3FooVYKF : $@convention(thin) () -> @error Foo
+func throwsDifferentFromEnclosing() throws(Foo) {
+  do {
+    throw Bar()
+  } catch {
+    print("Bar was barred")
+  }
+
+  // CHECK: throw [[ERROR:%.*]] : $Foo
+  throw Foo()
+}
+
+
 // CHECK-LABEL:      sil_vtable MySubclass {
 // CHECK-NEXT:   #MyClass.init!allocator: <E where E : Error> (MyClass.Type) -> (() throws(E) -> ()) throws(E) -> MyClass : @$s12typed_throws10MySubclassC4bodyACyyxYKXE_txYKcs5ErrorRzlufC [override]
 // CHECK-NEXT:  #MyClass.f: (MyClass) -> () throws -> () : @$s12typed_throws10MySubclassC1fyyAA0C5ErrorOYKFAA0C5ClassCADyyKFTV [override]