Always emit "unsafe does not cover any unsafe constructs" warning

Check for unsafe constructs in all modes, so that we can emit the
"unsafe does not cover any unsafe constructs" warning consistently.
One does not need to write "unsafe" outside of strict memory safety
mode, but if you do... it needs to cover unsafe behavior.

Author: DougGregor

lib/Sema/CSApply.cpp

@@ -8149,7 +8149,7 @@ Expr *ExprRewriter::convertLiteralInPlace(
     Diag<> brokenProtocolDiag, Diag<> brokenBuiltinProtocolDiag) {
   // If coercing a literal to an unresolved type, we don't try to look up the
   // witness members, just do it.
-  if (type->is<UnresolvedType>()) {
+  if (type->is<UnresolvedType>() || type->is<ErrorType>()) {
     cs.setType(literal, type);
     return literal;
   }

lib/Sema/TypeCheckEffects.cpp

@@ -1187,8 +1187,7 @@ class Classification {
     Classification result;
     bool considerAsync = !onlyEffect || *onlyEffect == EffectKind::Async;
     bool considerThrows = !onlyEffect || *onlyEffect == EffectKind::Throws;
-    bool considerUnsafe = (!onlyEffect || *onlyEffect == EffectKind::Unsafe) &&
-        ctx.LangOpts.hasFeature(Feature::StrictMemorySafety);
+    bool considerUnsafe = (!onlyEffect || *onlyEffect == EffectKind::Unsafe);
 
     // If we're tracking "unsafe" effects, compute them here.
     if (considerUnsafe) {
@@ -1708,8 +1707,7 @@ class ApplyClassifier {
         !fnType->isAsync() &&
         !E->isImplicitlyAsync() &&
         !hasAnyConformances &&
-        (fnRef.getExplicitSafety() == ExplicitSafety::Safe ||
-         !ctx.LangOpts.hasFeature(Feature::StrictMemorySafety))) {
+        fnRef.getExplicitSafety() == ExplicitSafety::Safe) {
       return Classification();
     }
 
@@ -1928,7 +1926,6 @@ class ApplyClassifier {
     // If the safety of the callee is unspecified, check the safety of the
     // arguments specifically.
     if (hasUnspecifiedSafety &&
-        ctx.LangOpts.hasFeature(Feature::StrictMemorySafety) &&
         !(assumedSafeArguments && assumedSafeArguments->contains(E))) {
       classifyApplyEffect(EffectKind::Unsafe);
     }
@@ -4554,8 +4551,7 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         Ctx.Diags.diagnose(S->getForLoc(), diag::for_unsafe_without_unsafe)
           .fixItInsert(insertionLoc, "unsafe ");
       }
-    } else if (S->getUnsafeLoc().isValid() &&
-               Ctx.LangOpts.hasFeature(Feature::StrictMemorySafety)) {
+    } else if (S->getUnsafeLoc().isValid()) {
       // Extraneous "unsafe" on the sequence.
       Ctx.Diags.diagnose(S->getUnsafeLoc(), diag::no_unsafe_in_unsafe_for)
         .fixItRemove(S->getUnsafeLoc());
@@ -4600,9 +4596,6 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
   }
 
   void diagnoseRedundantUnsafe(UnsafeExpr *E) const {
-    if (!Ctx.LangOpts.hasFeature(Feature::StrictMemorySafety))
-      return;
-
     // Silence this warning in the expansion of the _SwiftifyImport macro.
     // This is a hack because it's tricky to determine when to insert "unsafe".
     unsigned bufferID =

lib/Sema/TypeCheckUnsafe.cpp

@@ -338,10 +338,6 @@ bool swift::enumerateUnsafeUses(ArrayRef<ProtocolConformanceRef> conformances,
     if (conformance.isInvalid())
       continue;
 
-    ASTContext &ctx = conformance.getProtocol()->getASTContext();
-    if (!ctx.LangOpts.hasFeature(Feature::StrictMemorySafety))
-      return false;
-
     if (!conformance.hasEffect(EffectKind::Unsafe))
       continue;
 
@@ -410,9 +406,6 @@ bool swift::isUnsafeInConformance(const ValueDecl *requirement,
 
 void swift::diagnoseUnsafeType(ASTContext &ctx, SourceLoc loc, Type type,
                                llvm::function_ref<void(Type)> diagnose) {
-  if (!ctx.LangOpts.hasFeature(Feature::StrictMemorySafety))
-    return;
-
   if (!type->isUnsafe())
     return;
 

test/Constraints/issue-66553.swift

@@ -4,7 +4,7 @@
 
 func baz(y: [Int], z: Int) -> Int {
   switch z {
-  case y[let z]: // expected-error {{'let' binding pattern cannot appear in an expression}}
+  case y[let z]: // expected-error 2{{'let' binding pattern cannot appear in an expression}}
     z
   default:
     z

test/Parse/matching_patterns.swift

@@ -406,7 +406,7 @@ func testNonBinding5(_ x: Int, y: [Int]) {
 func testNonBinding6(y: [Int], z: Int) -> Int {
   switch 0 {
   // We treat 'z' here as a binding, which is invalid.
-  case let y[z]: // expected-error {{pattern variable binding cannot appear in an expression}}
+  case let y[z]: // expected-error 2{{pattern variable binding cannot appear in an expression}}
     z
   case y[z]: // This is fine
     0

test/Unsafe/unsafe_nonstrict.swift

@@ -14,5 +14,5 @@ func acceptP<T: P>(_: T) { }
 func testItAll(ut: UnsafeType, x: X, i: Int) {
   _ = unsafe ut
   unsafe acceptP(x)
-  _ = unsafe i
+  _ = unsafe i // expected-warning{{no unsafe operations occur within 'unsafe' expression}}
 }

test/stmt/typed_throws.swift

@@ -361,11 +361,11 @@ func testSequenceExpr() async throws(Never) {
 
   _ = unsafe await try! getIntAsync() + getIntAsync()
   // expected-warning@-1 {{'try' must precede 'await'}}
-
+  // expected-warning@-2{{no unsafe operations occur within 'unsafe' expression}}
   _ = try unsafe await try! getIntAsync() + getIntAsync()
   // expected-warning@-1 {{'try' must precede 'await'}}
   // expected-warning@-2 {{no calls to throwing functions occur within 'try' expression}}
-
+  // expected-warning@-3{{no unsafe operations occur within 'unsafe' expression}}
   try _ = (try! getInt()) + getInt()
   // expected-error@-1:29 {{thrown expression type 'any Error' cannot be converted to error type 'Never'}}