Merge pull request #1642 from ahoppen/SR-317-Optional-Throwing-Parame…

…teter-Rethrows [Sema] SR-317: Allow rethrowing functions to take an optional function parameter
apple · Mar 14, 2016 · 2293d28 · 2293d28
2 parents c7dfed7 + 3f115d4
commit 2293d28
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Showing 3 changed files with 42 additions and 3 deletions.
diff --git a/lib/Sema/TypeCheckAttr.cpp b/lib/Sema/TypeCheckAttr.cpp
@@ -1237,7 +1237,7 @@ void AttributeChecker::visitRethrowsAttr(RethrowsAttr *attr) {
   auto fn = cast<AbstractFunctionDecl>(D);
   for (auto paramList : fn->getParameterLists()) {
     for (auto param : *paramList)
-      if (hasThrowingFunctionParameter(param->getType()->getCanonicalType()))
+      if (hasThrowingFunctionParameter(param->getType()->lookThroughAllAnyOptionalTypes()->getCanonicalType()))
         return;
   }
 

diff --git a/lib/Sema/TypeCheckError.cpp b/lib/Sema/TypeCheckError.cpp
@@ -136,6 +136,16 @@ class AbstractFunction {
   static AbstractFunction decomposeFunction(Expr *fn) {
     assert(fn->getValueProvidingExpr() == fn);
 
+    // Look through Optional unwraps
+    while (true) {
+      if (auto conversion = dyn_cast<ForceValueExpr>(fn)) {
+        fn = conversion->getSubExpr()->getValueProvidingExpr();
+      } else if (auto conversion = dyn_cast<BindOptionalExpr>(fn)) {
+        fn = conversion->getSubExpr()->getValueProvidingExpr();
+      } else {
+        break;
+      }
+    }
     // Look through function conversions.
     while (auto conversion = dyn_cast<FunctionConversionExpr>(fn)) {
       fn = conversion->getSubExpr()->getValueProvidingExpr();
@@ -480,7 +490,7 @@ class ApplyClassifier {
 
   Classification classifyThrowingParameterBody(ParamDecl *param,
                                                PotentialReason reason) {
-    assert(param->getType()->castTo<AnyFunctionType>()->throws());
+    assert(param->getType()->lookThroughAllAnyOptionalTypes()->castTo<AnyFunctionType>()->throws());
 
     // If we're currently doing rethrows-checking on the body of the
     // function which declares the parameter, it's rethrowing-only.
@@ -660,7 +670,7 @@ class ApplyClassifier {
 
     // Otherwise, if the original parameter type was not a throwing
     // function type, it does not contribute to 'rethrows'.
-    auto paramFnType = paramType->getAs<AnyFunctionType>();
+    auto paramFnType = paramType->lookThroughAllAnyOptionalTypes()->getAs<AnyFunctionType>();
     if (!paramFnType || !paramFnType->throws())
       return Classification();
 

diff --git a/test/decl/func/rethrows.swift b/test/decl/func/rethrows.swift
@@ -313,6 +313,35 @@ func testGenericMethodCallACHandled<P: MyProto>(s: P) throws {
   try P.static_callAC(raise())
 }
 
+/** Optional closure parameters */
+
+func testForceUnwrappedOptionalFunctionParameter(f: (() throws -> Void)?) rethrows {
+  try f!()
+}
+
+func testBindOptionalFunctionParameter(f: (() throws -> Void)?) rethrows {
+  try f?()
+}
+
+func testImplicitlyUnwrappedFunctionParameter(f: (() throws -> Void)!) rethrows {
+  if f != nil {
+    try f()
+  }
+}
+
+func throwingFunc() throws {}
+
+func nonThrowingFunc() {}
+
+try testBindOptionalFunctionParameter(throwingFunc)
+testBindOptionalFunctionParameter(nonThrowingFunc)
+testBindOptionalFunctionParameter(nil)
+
+try testImplicitlyUnwrappedFunctionParameter(throwingFunc)
+testImplicitlyUnwrappedFunctionParameter(nonThrowingFunc)
+testImplicitlyUnwrappedFunctionParameter(nil)
+
+
 /** Miscellaneous bugs **/
 
 // rdar://problem/21967164 - Non-throwing closures are incorrectly marked as throwing in rethrow contexts