Fixed some tests

Remaining failures:

DebugInfo/guard-let-scope4.swift
expr/closure/closures.swift
SILGen/capture-transitive.swift
SILGen/dynamic_self.swift
SILGen/unowned-class-bound-generic-parameter.swift

Author: nickolas-pohilets

test/Parse/invalid.swift

@@ -119,7 +119,7 @@ prefix func %<T>(x: T) -> T { return x } // No error expected - the < is conside
 
 struct Weak<T: class> { // expected-error {{'class' constraint can only appear on protocol declarations}}
   // expected-note@-1 {{did you mean to write an 'AnyObject' constraint?}} {{16-21=AnyObject}}
-  weak let value: T // expected-error {{'weak' must be a mutable variable, because it may change at runtime}} expected-error {{'weak' variable should have optional type 'T?'}} expected-error {{'weak' must not be applied to non-class-bound 'T'; consider adding a protocol conformance that has a class bound}}
+  weak let value: T // expected-error {{'weak' variable should have optional type 'T?'}} expected-error {{'weak' must not be applied to non-class-bound 'T'; consider adding a protocol conformance that has a class bound}}
 }
 
 let x: () = ()

test/SILGen/capture_order.swift

@@ -28,7 +28,7 @@ public func captureBeforeDefWeakVar(obj: AnyObject) -> () -> AnyObject? {
     return weakObj // expected-note {{captured here}}
   }
   let closure = getter
-  weak var weakObj: AnyObject? = obj // expected-note{{captured value declared here}}
+  weak let weakObj: AnyObject? = obj // expected-note{{captured value declared here}}
   return closure
 }
 
@@ -125,7 +125,7 @@ class С_47389 {
     let bar = { [weak self] in
     // expected-error@-1 {{closure captures 'bar' before it is declared}}
     // expected-note@-2 {{captured value declared here}}
-    // expected-warning@-3 {{variable 'self' was written to, but never read}}
+    // expected-warning@-3 {{capture 'self' was never used}}
       bar2()
     }
     func bar2() {

test/SILOptimizer/definite_init_diagnostics.swift

@@ -103,14 +103,15 @@ func test2() {
 
 
   // Weak
+  // expected-warning @+1 {{variable 'w1' was never mutated; consider changing to 'let' constant}} {{8-11=let}}
   weak var w1 : SomeClass?
   _ = w1                // ok: default-initialized
 
   // Note: with -enable-copy-propagation, we also expect: {{weak reference will always be nil because the referenced object is deallocated here}}
   // expected-warning@+3 {{instance will be immediately deallocated because variable 'w2' is 'weak'}}
   // expected-note@+2 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@+1 {{'w2' declared here}}
-  weak var w2 = SomeClass()
+  weak let w2 = SomeClass()
   _ = w2                // ok
 
 

test/Sema/diag_unowned_immediate_deallocation.swift

@@ -271,7 +271,7 @@ func testUnownedVariableBindingDiag() throws {
 }
 
 func testMultipleBindingDiag() {
-  weak var c1 = C(), c2: C? = C(), c3: C? = D()
+  weak let c1 = C(), c2: C? = C(), c3: C? = D()
   // expected-warning@-1 {{instance will be immediately deallocated because variable 'c1' is 'weak'}}
   // expected-note@-2 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-3 {{'c1' declared here}}
@@ -297,7 +297,7 @@ func testMultipleBindingDiag() {
 }
 
 func testTupleAndParenBinding() throws {
-  weak var ((c1), c2, c3): (C?, C?, C?) = (C() as C, (D()), try D(throwing: ()))
+  weak let ((c1), c2, c3): (C?, C?, C?) = (C() as C, (D()), try D(throwing: ()))
   // expected-warning@-1 {{instance will be immediately deallocated because variable 'c1' is 'weak'}}
   // expected-note@-2 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-3 {{'c1' declared here}}
@@ -323,11 +323,11 @@ func testTupleAndParenBinding() throws {
 }
 
 func testInitializationThroughClassArchetypeDiag<T : ClassProtocol>(_ t: T, _ p: ClassProtocol) throws {
-  weak var t1: T? = T() // expected-warning {{instance will be immediately deallocated because variable 't1' is 'weak'}}
+  weak let t1: T? = T() // expected-warning {{instance will be immediately deallocated because variable 't1' is 'weak'}}
   // expected-note@-1 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-2 {{'t1' declared here}}
 
-  weak var t2: ClassProtocol? = T(failable: ()) // expected-warning {{instance will be immediately deallocated because variable 't2' is 'weak'}}
+  weak let t2: ClassProtocol? = T(failable: ()) // expected-warning {{instance will be immediately deallocated because variable 't2' is 'weak'}}
   // expected-note@-1 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-2 {{'t2' declared here}}
 
@@ -342,7 +342,7 @@ func testInitializationThroughClassArchetypeDiag<T : ClassProtocol>(_ t: T, _ p:
   let optionalTType: T.Type? = T.self
   let optionalPType: ClassProtocol.Type? = type(of: p)
 
-  weak var t5 = optionalTType?.init(failable: ()) // expected-warning {{instance will be immediately deallocated because variable 't5' is 'weak'}}
+  weak let t5 = optionalTType?.init(failable: ()) // expected-warning {{instance will be immediately deallocated because variable 't5' is 'weak'}}
   // expected-note@-1 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-2 {{'t5' declared here}}
 
@@ -404,12 +404,12 @@ class C1 {
 }
 
 func testInitializationThroughMetaclassDiag(_ t: C.Type) {
-  weak var c1: C? = t.init() // expected-warning {{instance will be immediately deallocated because variable 'c1' is 'weak'}}
+  weak let c1: C? = t.init() // expected-warning {{instance will be immediately deallocated because variable 'c1' is 'weak'}}
   // expected-note@-1 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-2 {{'c1' declared here}}
 
   let optionalCType: C.Type? = t
-  weak var c2 = optionalCType?.init(failable: ()) // expected-warning {{instance will be immediately deallocated because variable 'c2' is 'weak'}}
+  weak let c2 = optionalCType?.init(failable: ()) // expected-warning {{instance will be immediately deallocated because variable 'c2' is 'weak'}}
   // expected-note@-1 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-2 {{'c2' declared here}}
 
@@ -439,7 +439,7 @@ func testInitializationThroughTupleElementDiag() {
 class E<T> {}
 
 func testGenericWeakClassDiag() {
-  weak var e = E<String>()
+  weak let e = E<String>()
   // expected-warning@-1 {{instance will be immediately deallocated because variable 'e' is 'weak'}}
   // expected-note@-2 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-3 {{'e' declared here}}
@@ -465,7 +465,7 @@ extension Optional {
 }
 
 func testDontDiagnoseOnUnrelatedInitializer() {
-  weak var c = C?(dontDiagnoseOnThis: ())
+  weak let c = C?(dontDiagnoseOnThis: ())
   unowned let c1 = C?(dontDiagnoseOnThis: ())!
   _ = c; _ = c1
 }
@@ -476,8 +476,8 @@ class F {
 }
 
 func testDontDiagnoseThroughMembers() {
-  weak var c1 = F().c
-  weak var c2 = F().makeC()
+  weak let c1 = F().c
+  weak let c2 = F().makeC()
   _ = c1; _ = c2
 }
 
@@ -488,7 +488,7 @@ func testDontDiagnoseOnStrongVariable() {
 }
 
 func testDontDiagnoseThroughImmediatelyEvaluatedClosure() {
-  weak var c1 = { C() }()
+  weak let c1 = { C() }()
   unowned let c2 = { C() }()
   _ = c1; _ = c2
 }

test/decl/var/properties.swift

@@ -114,7 +114,7 @@ var x15: Int {
   // For the purpose of this test we need to use an attribute that cannot be
   // applied to the getter.
   weak
-  var foo: SomeClass? = SomeClass()  // expected-warning {{variable 'foo' was written to, but never read}}
+  var foo: SomeClass? = SomeClass()  // expected-warning {{variable 'foo' was never used; consider replacing with '_' or removing it}}
   // expected-warning@-1 {{instance will be immediately deallocated because variable 'foo' is 'weak'}}
   // expected-note@-2 {{a strong reference is required to prevent the instance from being deallocated}}
   // expected-note@-3 {{'foo' declared here}}

test/decl/var/variables.swift

@@ -87,8 +87,10 @@ var shouldWarnWithoutSugar = (arrayOfEmptyTuples as Array<()>) // expected-warni
 
 class SomeClass {}
 
-// <rdar://problem/16877304> weak let's should be rejected
-weak let V = SomeClass()  // expected-error {{'weak' must be a mutable variable, because it may change at runtime}}
+weak let V = SomeClass() // ok since SE-0481
+// expected-warning@-1 {{instance will be immediately deallocated because variable 'V' is 'weak'}}
+// expected-note@-2 {{'V' declared here}}
+// expected-note@-3 {{a strong reference is required to prevent the instance from being deallocated}}
 
 let a = b ; let b = a
 // expected-error@-1 {{circular reference}}

test/expr/closure/closures.swift

@@ -262,12 +262,12 @@ class ExplicitSelfRequiredTest {
   // because its `sawError` flag is set to true. To preserve the "capture 'y' was never used" warnings
   // above, we put these cases in their own method.
   func weakSelfError() {
-    doVoidStuff({ [weak self] in x += 1 }) // expected-error {{reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{variable 'self' was written to, but never read}}
-    doVoidStuffNonEscaping({ [weak self] in x += 1 }) // expected-warning {{reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{variable 'self' was written to, but never read}}
-    doStuff({ [weak self] in x+1 }) // expected-error {{reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{variable 'self' was written to, but never read}}
-    doVoidStuff({ [weak self] in _ = method() }) // expected-error {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{variable 'self' was written to, but never read}}
-    doVoidStuffNonEscaping({ [weak self] in _ = method() }) // expected-warning {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{variable 'self' was written to, but never read}}
-    doStuff({ [weak self] in method() }) // expected-error {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{variable 'self' was written to, but never read}}
+    doVoidStuff({ [weak self] in x += 1 }) // expected-error {{reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{capture 'self' was never used}}
+    doVoidStuffNonEscaping({ [weak self] in x += 1 }) // expected-warning {{reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{capture 'self' was never used}}
+    doStuff({ [weak self] in x+1 }) // expected-error {{reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{capture 'self' was never used}}
+    doVoidStuff({ [weak self] in _ = method() }) // expected-error {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{capture 'self' was never used}}
+    doVoidStuffNonEscaping({ [weak self] in _ = method() }) // expected-warning {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{capture 'self' was never used}}
+    doStuff({ [weak self] in method() }) // expected-error {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-warning {{capture 'self' was never used}}
   }
 }
 
@@ -374,7 +374,7 @@ extension SomeClass {
     //expected-error@-3{{reference to property 'in' in closure requires explicit use of 'self' to make capture semantics explicit}}
     //expected-note@-4{{reference 'self.' explicitly}}
 
-    // expected-warning @+1 {{variable 'self' was written to, but never read}}
+    // expected-warning @+1 {{capture 'self' was never used}}
     doStuff { [weak self&field] in 42 }  // expected-error {{expected ']' at end of capture list}}
 
   }
@@ -511,6 +511,7 @@ func lvalueCapture<T>(c: GenericClass<T>) {
     _ = wc
 
     cc = wc!
+    wc = cc
   }
 }
 
@@ -1522,21 +1523,21 @@ final class AutoclosureTests {
       }
     }
 
-    doVoidStuff { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    doVoidStuff { [weak self] in // expected-warning {{capture 'self' was never used}}
       withNonEscapingAutoclosure(bar()) // expected-error {{call to method 'bar' in closure requires explicit use of 'self' to make capture semantics explicit}}
     }
 
-    doVoidStuff { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    doVoidStuff { [weak self] in // expected-warning {{capture 'self' was never used}}
       withEscapingAutoclosure(bar()) // expected-error {{call to method 'bar' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-note {{reference 'self.' explicitly}}
     }
 
-    doVoidStuff { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    doVoidStuff { [weak self] in // expected-warning {{capture 'self' was never used}}
       doVoidStuff { // expected-note {{capture 'self' explicitly to enable implicit 'self' in this closure}}
         withNonEscapingAutoclosure(bar()) // expected-error {{all to method 'bar' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-note {{reference 'self.' explicitly}}
       }
     }
 
-    doVoidStuff { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    doVoidStuff { [weak self] in // expected-warning {{capture 'self' was never used}}
       doVoidStuff {
         withEscapingAutoclosure(bar()) // expected-error {{call to method 'bar' in closure requires explicit use of 'self' to make capture semantics explicit}} expected-note {{reference 'self.' explicitly}}
       }
@@ -1771,21 +1772,21 @@ class rdar129475277 {
   func method() {}
 
   func test1() {
-    takesEscapingWithAllowedImplicitSelf { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    takesEscapingWithAllowedImplicitSelf { [weak self] in // expected-warning {{capture 'self' was never used}}
       takesEscapingWithAllowedImplicitSelf {
         method() // expected-warning {{call to method 'method' in closure requires explicit use of 'self' to make capture semantics explicit}}
       }
     }
 
-    takesEscapingWithAllowedImplicitSelf { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    takesEscapingWithAllowedImplicitSelf { [weak self] in // expected-warning {{capture 'self' was never used}}
       takesEscapingWithAllowedImplicitSelf {
         doVoidStuffNonEscaping {
           withNonEscapingAutoclosure(bar()) // expected-warning {{call to method 'bar' in closure requires explicit use of 'self' to make capture semantics explicit}}
         }
       }
     }
 
-    takesEscapingWithAllowedImplicitSelf { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    takesEscapingWithAllowedImplicitSelf { [weak self] in // expected-warning {{capture 'self' was never used}}
       withNonEscapingAutoclosure(bar()) // expected-warning {{call to method 'bar' in closure requires explicit use of 'self' to make capture semantics explicit}}
     }
   }
@@ -1818,15 +1819,15 @@ class TestExtensionOnOptionalSelf {
 
 extension TestExtensionOnOptionalSelf? {
   func foo() {
-    _ = { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    _ = { [weak self] in // expected-warning {{capture 'self' was never used}}
       foo() // expected-error {{call to method 'foo' in closure requires explicit use of 'self' to make capture semantics explicit}}
     }
 
     _ = {
       foo()
     }
 
-    _ = { [weak self] in // expected-warning {{variable 'self' was written to, but never read}}
+    _ = { [weak self] in // expected-warning {{capture 'self' was never used}}
       _ = {
         foo()
       }