Merge pull request swiftlang#77598 from rintaro/astgen-switchexpr

[ASTGen] Generate 'switch' expressions

Author: rintaro

lib/ASTGen/Sources/ASTGen/Exprs.swift

@@ -161,8 +161,8 @@ extension ASTGenVisitor {
       return self.generate(subscriptCallExpr: node).asExpr
     case .superExpr(let node):
       return self.generate(superExpr: node).asExpr
-    case .switchExpr:
-      break
+    case .switchExpr(let node):
+      return self.generate(switchExpr: node).asExpr
     case .ternaryExpr:
       preconditionFailure("TernaryExprSyntax only appear after operator folding")
     case .tryExpr(let node):
@@ -1063,6 +1063,18 @@ extension ASTGenVisitor {
     return .createParsed(self.ctx, superLoc: self.generateSourceLoc(node))
   }
 
+  func generate(switchExpr node: SwitchExprSyntax) -> BridgedSingleValueStmtExpr {
+    let stmt = self.generateSwitchStmt(switchExpr: node)
+
+    // Wrap in a SingleValueStmtExpr to embed as an expression.
+    return .createWithWrappedBranches(
+      ctx,
+      stmt: stmt.asStmt,
+      declContext: declContext,
+      mustBeExpr: true
+    )
+  }
+
   func generate(tryExpr node: TryExprSyntax) -> BridgedExpr {
     let tryLoc = self.generateSourceLoc(node.tryKeyword)
     let subExpr = self.generate(expr: node.expression)

test/ASTGen/exprs.swift

@@ -193,3 +193,11 @@ func testOptionalChain(value: TestStruct) {
   var value: Int? = 1
   value? += 1
 }
+
+func testSwitchExpr(value: Int) {
+  let _ = switch value {
+    case 0: "foo"
+    case ...100: "bar"
+    default: "baz"
+  }
+}