Merge pull request swiftlang#35237 from LucianoPAlmeida/SR-13753-stmt

[SR-13753][Diagnostics] Downgrade l-value unused diagnostics to warning

Author: LucianoPAlmeida

include/swift/AST/DiagnosticsSema.def

@@ -3786,8 +3786,8 @@ ERROR(expression_unused_closure,none,
       "closure expression is unused", ())
 ERROR(expression_unused_function,none,
       "expression resolves to an unused function", ())
-ERROR(expression_unused_lvalue,none,
-      "expression resolves to an unused %select{variable|property|subscript}0", (unsigned))
+WARNING(expression_unused_lvalue,none,
+        "expression resolves to an unused %select{variable|property|subscript}0", (unsigned))
 WARNING(expression_unused_result_call,none,
         "result of call to %0 is unused", (DeclName))
 WARNING(expression_unused_result_operator,none,

lib/SILOptimizer/Mandatory/DataflowDiagnostics.cpp

@@ -63,7 +63,7 @@ static void diagnoseMissingReturn(const UnreachableInst *UI,
   if (!BS->empty()) {
     auto element = BS->getLastElement();
     if (auto expr = element.dyn_cast<Expr *>()) {
-      if (expr->getType()->isEqual(ResTy)) {
+      if (expr->getType()->getRValueType()->isEqual(ResTy)) {
         Context.Diags.diagnose(
           expr->getStartLoc(),
           diag::missing_return_last_expr, ResTy,

test/Parse/consecutive_statements.swift

@@ -6,13 +6,13 @@ func statement_starts() {
 
   f(0)
   f (0)
-  f // expected-error{{expression resolves to an unused variable}}
+  f // expected-warning{{expression resolves to an unused variable}}
   (0) // expected-warning {{integer literal is unused}}
 
   var a = [1,2,3]
   a[0] = 1
   a [0] = 1
-  a // expected-error{{expression resolves to an unused variable}}
+  a // expected-warning{{expression resolves to an unused variable}}
   [0, 1, 2] // expected-warning {{expression of type '[Int]' is unused}}
 }
 

test/Parse/super.swift

@@ -34,15 +34,15 @@ class D : B {
   }
 
   func super_calls() {
-    super.foo        // expected-error {{expression resolves to an unused property}}
+    super.foo        // expected-warning {{expression resolves to an unused property}}
     super.foo.bar    // expected-error {{value of type 'Int' has no member 'bar'}}
     super.bar        // expected-error {{expression resolves to an unused function}}
     super.bar()
     // FIXME: should also say "'super.init' cannot be referenced outside of an initializer"
     super.init // expected-error{{no exact matches in reference to initializer}}
     super.init() // expected-error{{'super.init' cannot be called outside of an initializer}}
     super.init(0) // expected-error{{'super.init' cannot be called outside of an initializer}} // expected-error {{missing argument label 'x:' in call}}
-    super[0]        // expected-error {{expression resolves to an unused subscript}}
+    super[0]        // expected-warning {{expression resolves to an unused subscript}}
     super
       .bar()
   }

test/SILOptimizer/return.swift

@@ -159,3 +159,57 @@ struct StructWithIUOinit : InitProtocol {
   init!(_ x: Int) {  } // no missing-return error
 }
 
+func testSR13753() {
+  // SR-13753
+  let _ : () -> Int = {
+    var x : Int {
+      get { 0 }
+      set { }
+    }
+    x // expected-error {{missing return in a closure expected to return 'Int'; did you mean to return the last expression?}} {{5-5=return }}
+    // expected-warning@-1 {{setter argument 'newValue' was never used, but the property was accessed}}
+    // expected-note@-2 {{did you mean to use 'newValue' instead of accessing the property's current value?}}
+    // expected-warning@-3 {{expression resolves to an unused variable}} 
+  }
+
+  func f() -> Int {
+    var x : Int {
+        get { 0 }
+        set { }
+    }
+    x // expected-error {{missing return in a function expected to return 'Int'; did you mean to return the last expression?}} {{5-5=return }}
+    // expected-warning@-1 {{setter argument 'newValue' was never used, but the property was accessed}}
+    // expected-note@-2 {{did you mean to use 'newValue' instead of accessing the property's current value?}}
+    // expected-warning@-3 {{expression resolves to an unused variable}} 
+  } 
+
+  let _ : () -> Int = {
+    var x : UInt {
+      get { 0 }
+      set { }
+    }
+    x 
+    // expected-warning@-1 {{setter argument 'newValue' was never used, but the property was accessed}}
+    // expected-note@-2 {{did you mean to use 'newValue' instead of accessing the property's current value?}}
+    // expected-warning@-3 {{expression resolves to an unused variable}} 
+  } // expected-error {{missing return in a closure expected to return 'Int'}}
+
+  func f1() -> Int {
+    var x : UInt {
+        get { 0 }
+        set { }
+    }
+    x 
+    // expected-warning@-1 {{setter argument 'newValue' was never used, but the property was accessed}}
+    // expected-note@-2 {{did you mean to use 'newValue' instead of accessing the property's current value?}}
+    // expected-warning@-3 {{expression resolves to an unused variable}} 
+  } // expected-error {{missing return in a function expected to return 'Int'}}
+
+  let _ : () -> Int = {
+    var x : Int = 0 // expected-warning {{variable 'x' was never mutated; consider changing to 'let' constant}}
+    var _ : Int = 0
+    
+    x // expected-error{{missing return in a closure expected to return 'Int'; did you mean to return the last expression?}} {{5-5=return }}
+    //expected-warning@-1{{expression resolves to an unused variable}}
+  }
+}

test/expr/expressions.swift

@@ -21,9 +21,9 @@ func1()
 _ = 4+7
 
 var bind_test1 : () -> () = func1
-var bind_test2 : Int = 4; func1 // expected-error {{expression resolves to an unused variable}}
+var bind_test2 : Int = 4; func1 // expected-warning {{expression resolves to an unused variable}}
 
-(func1, func2) // expected-error {{expression resolves to an unused variable}}
+(func1, func2) // expected-warning {{expression resolves to an unused variable}}
 
 func basictest() {
   // Simple integer variables.