[Multi-expression closures] Add support for 'throw' statement.

Author: DougGregor

lib/Sema/CSClosure.cpp

@@ -176,6 +176,23 @@ class ClosureConstraintGenerator
   void visitContinueStmt(ContinueStmt *continueStmt) { }
   void visitDeferStmt(DeferStmt *deferStmt) { }
 
+  void visitThrowStmt(ThrowStmt *throwStmt) {
+    Type exnType =
+        cs.getASTContext().getErrorDecl()->getDeclaredInterfaceType();
+    if (!exnType) {
+      hadError = true;
+      return;
+    }
+
+    SolutionApplicationTarget target(
+        throwStmt->getSubExpr(), closure, CTP_ThrowStmt, exnType,
+        /*isDiscarded=*/false);
+    if (cs.generateConstraints(target, FreeTypeVariableBinding::Disallow))
+      hadError = true;
+
+    cs.setSolutionApplicationTarget(throwStmt, target);
+  }
+
 #define UNSUPPORTED_STMT(STMT) void visit##STMT##Stmt(STMT##Stmt *) { \
       llvm_unreachable("Unsupported statement kind " #STMT);          \
   }
@@ -185,7 +202,6 @@ class ClosureConstraintGenerator
   UNSUPPORTED_STMT(Case)
   UNSUPPORTED_STMT(Fallthrough)
   UNSUPPORTED_STMT(Fail)
-  UNSUPPORTED_STMT(Throw)
   UNSUPPORTED_STMT(PoundAssert)
 #undef UNSUPPORTED_STMT
 };
@@ -450,6 +466,17 @@ class ClosureConstraintApplication
     return deferStmt;
   }
 
+  ASTNode visitThrowStmt(ThrowStmt *throwStmt) {
+    // Rewrite the condition.
+    auto target = *solution.getConstraintSystem()
+        .getSolutionApplicationTarget(throwStmt);
+    if (auto result = rewriteTarget(target))
+      throwStmt->setSubExpr(result->getAsExpr());
+    else
+      hadError = true;
+    return throwStmt;
+  }
+
 #define UNSUPPORTED_STMT(STMT) ASTNode visit##STMT##Stmt(STMT##Stmt *) { \
       llvm_unreachable("Unsupported statement kind " #STMT);          \
   }
@@ -459,7 +486,6 @@ class ClosureConstraintApplication
   UNSUPPORTED_STMT(Case)
   UNSUPPORTED_STMT(Fallthrough)
   UNSUPPORTED_STMT(Fail)
-  UNSUPPORTED_STMT(Throw)
   UNSUPPORTED_STMT(PoundAssert)
 #undef UNSUPPORTED_STMT
 

test/expr/closure/multi_statement.swift

@@ -8,10 +8,14 @@ func maybeGetValue<T>(_ value: T) -> T? {
   return value
 }
 
+enum MyError: Error {
+  case featureIsTooCool
+}
+
 func random(_: Int) -> Bool { return false }
 
-func mapWithMoreStatements(ints: [Int]) {
-  let _ = ints.map { i in
+func mapWithMoreStatements(ints: [Int]) throws {
+  let _ = try ints.map { i in
     guard var actualValue = maybeGetValue(i) else {
       return String(0)
     }
@@ -46,7 +50,9 @@ func mapWithMoreStatements(ints: [Int]) {
       if j % 7 == 0 {
         continue
       }
+ 
       print("even")
+      throw MyError.featureIsTooCool
     }
 
     return String(value)