Merge pull request #11859 from CodaFi/impl-lied

Author: swift-ci

lib/SILGen/SILGenStmt.cpp

@@ -212,7 +212,22 @@ void StmtEmitter::visitBraceStmt(BraceStmt *S) {
       if (auto *S = ESD.dyn_cast<Stmt*>()) {
         if (S->isImplicit()) continue;
       } else if (auto *E = ESD.dyn_cast<Expr*>()) {
-        if (E->isImplicit()) continue;
+        // Optional chaining expressions are wrapped in a structure like.
+        //
+        // (optional_evaluation_expr implicit type='T?'
+        //   (call_expr type='T?'
+        //     (exprs...
+        //
+        // Walk through it to find out if the statement is actually implicit.
+        if (auto *OEE = dyn_cast<OptionalEvaluationExpr>(E)) {
+          if (auto *IIO = dyn_cast<InjectIntoOptionalExpr>(OEE->getSubExpr()))
+            if (IIO->getSubExpr()->isImplicit()) continue;
+          if (auto *C = dyn_cast<CallExpr>(OEE->getSubExpr()))
+            if (C->isImplicit()) continue;
+        } else if (E->isImplicit()) {
+          // Ignore all other implicit expressions.
+          continue;
+        }
       }
 
       if (StmtType != UnknownStmtType) {

test/SILGen/unreachable_code.swift

@@ -111,6 +111,15 @@ func testUnreachableCase5(a : Tree) {
   }
 }
 
+func testOptionalEvaluationBreak(a : Tree) {
+  class SR5763 { func foo() {} }
+  func createOptional() -> SR5763? { return SR5763() }
+  switch a {
+  case _:
+    break
+    createOptional()?.foo() // expected-warning {{code after 'break' will never be executed}}
+  }
+}
 
 func testUnreachableAfterThrow(e: Error) throws {
   throw e