Merge pull request swiftlang#29141 from slavapestov/capture-two-values-and-crash

SILGen: Fix crash when a closure captures two values with dynamic 'Self' type

Author: slavapestov

lib/SIL/TypeLowering.cpp

@@ -2300,9 +2300,7 @@ TypeConverter::getLoweredLocalCaptures(SILDeclRef fn) {
           continue;
 
         // We can always capture the storage in these cases.
-        Type captureType = capturedVar->getType();
-        if (auto *metatypeType = captureType->getAs<MetatypeType>())
-          captureType = metatypeType->getInstanceType();
+        Type captureType = capturedVar->getType()->getMetatypeInstanceType();
 
         if (auto *selfType = captureType->getAs<DynamicSelfType>()) {
           captureType = selfType->getSelfType();
@@ -2314,11 +2312,22 @@ TypeConverter::getLoweredLocalCaptures(SILDeclRef fn) {
           // mutable, we're going to be capturing a box or an address.
           if (captureType->getClassOrBoundGenericClass() &&
               capturedVar->isLet()) {
-            if (selfCapture)
+            // If we've already captured the same value already, just merge
+            // flags.
+            if (selfCapture && selfCapture->getDecl() == capture.getDecl()) {
               selfCapture = selfCapture->mergeFlags(capture);
-            else
+              continue;
+
+            // Otherwise, record the canonical self capture. It will appear
+            // at the end of the capture list.
+            } else if (!selfCapture) {
               selfCapture = capture;
-            continue;
+              continue;
+            }
+
+            // If we end up here, we have multiple different captured values
+            // with a dynamic 'Self' type. Handle this and any subsequent
+            // captures via the normal code path below.
           }
         }
 

test/SILGen/dynamic_self.swift

@@ -442,6 +442,25 @@ public class FunctionConversionTest : EmptyProtocol {
   }
 }
 
+public class CaptureTwoValuesTest {
+  public required init() {}
+
+  // CHECK-LABEL: sil [ossa] @$s12dynamic_self20CaptureTwoValuesTestC08capturesdE0yyFZ : $@convention(method) (@thick CaptureTwoValuesTest.Type) -> () {
+  public static func capturesTwoValues() {
+    let a = Self()
+    let b = Self()
+
+    // CHECK: function_ref @$s12dynamic_self20CaptureTwoValuesTestC08capturesdE0yyFZyycfU_ : $@convention(thin) (@guaranteed CaptureTwoValuesTest, @guaranteed CaptureTwoValuesTest) -> ()
+    _ = {
+      _ = a
+      _ = b
+      _ = Self.self
+    }
+
+    // CHECK-LABEL: sil private [ossa] @$s12dynamic_self20CaptureTwoValuesTestC08capturesdE0yyFZyycfU_ : $@convention(thin) (@guaranteed CaptureTwoValuesTest, @guaranteed CaptureTwoValuesTest) -> () {
+  }
+}
+
 // CHECK-LABEL: sil_witness_table hidden X: P module dynamic_self {
 // CHECK: method #P.f!1: {{.*}} : @$s12dynamic_self1XCAA1PA2aDP1f{{[_0-9a-zA-Z]*}}FTW