SILGen: Clean up partially-initialized array elements when lowering ArrayExpr

Author: slavapestov

lib/SILGen/SILGenExpr.cpp

@@ -3663,6 +3663,9 @@ RValue RValueEmitter::visitArrayExpr(ArrayExpr *E, SGFContext C) {
       emitBeginVarargs(SGF, loc, elementType, arrayTy,
                        E->getNumElements(), {});
 
+  // Cleanups for any elements that have been initialized so far.
+  SmallVector<CleanupHandle, 8> cleanups;
+
   for (unsigned index : range(E->getNumElements())) {
     auto destAddr = varargsInfo.getBaseAddress();
     if (index != 0) {
@@ -3671,14 +3674,27 @@ RValue RValueEmitter::visitArrayExpr(ArrayExpr *E, SGFContext C) {
       destAddr = SGF.B.createIndexAddr(loc, destAddr, indexValue);
     }
     auto &destTL = varargsInfo.getBaseTypeLowering();
-    // Use an invalid cleanup here because we're relying on the cleanup for
-    // the Array constructed inside emitBeginVarargs to destroy these values.
-    TemporaryInitialization init(destAddr, CleanupHandle::invalid());
+    // Create a dormant cleanup for the value in case we exit before the
+    // full array has been constructed.
+
+    CleanupHandle destCleanup = CleanupHandle::invalid();
+    if (!destTL.isTrivial()) {
+      destCleanup = SGF.enterDestroyCleanup(destAddr);
+      SGF.Cleanups.setCleanupState(destCleanup, CleanupState::Dormant);
+      cleanups.push_back(destCleanup);
+    }
+
+    TemporaryInitialization init(destAddr, destCleanup);
+
     ArgumentSource(E->getElements()[index])
         .forwardInto(SGF, varargsInfo.getBaseAbstractionPattern(), &init,
                      destTL);
   }
 
+  // Kill the per-element cleanups. The array will take ownership of them.
+  for (auto destCleanup : cleanups)
+    SGF.Cleanups.setCleanupState(destCleanup, CleanupState::Dead);
+
   RValue arg(SGF, loc, arrayTy,
              emitEndVarargs(SGF, loc, std::move(varargsInfo)));
 

test/Interpreter/arrays.swift

@@ -161,3 +161,25 @@ test()
 let mdaPerf = [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]]
 print(mdaPerf)
 // CHECK: {{\[}}[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]]
+
+class Deinitable {
+  deinit {
+    print("deinit called")
+  }
+}
+
+enum E : Error {
+  case error
+}
+
+func throwingFunc() throws -> Deinitable {
+  throw E.error
+}
+
+do {
+  let array = try [Deinitable(), throwingFunc()]
+} catch {
+  // CHECK: deinit called
+  // CHECK: error thrown
+  print("error thrown")
+}

test/SILGen/literals.swift

@@ -248,6 +248,7 @@ func makeBasic<T : FooProtocol>() -> T { return T() }
 // CHECK: return [[ARR]]
 
 // CHECK: bb2([[ERR:%.*]] : @owned $Error):
+// CHECK: destroy_addr [[POINTER]] : $*T
 // CHECK: [[DEALLOC:%.*]] = function_ref @$ss29_deallocateUninitializedArrayyySayxGnlF
 // CHECK: [[TMP:%.*]] = apply [[DEALLOC]]<T>([[ARR]])
 // CHECK: throw [[ERR]] : $Error