Stop propagating @unsafe/@safe from type definitions down to their members

Author: DougGregor

lib/AST/Decl.cpp

@@ -1228,10 +1228,6 @@ ExplicitSafety Decl::getExplicitSafety() const {
       if (auto extSafety = getExplicitSafetyFromAttrs(ext))
         return *extSafety;
     }
-
-    if (auto enclosingNominal = enclosingDC->getSelfNominalTypeDecl())
-      if (auto nominalSafety = getExplicitSafetyFromAttrs(enclosingNominal))
-        return *nominalSafety;
   }
 
   // If an extension extends an unsafe nominal type, it's unsafe.
@@ -1241,11 +1237,12 @@ ExplicitSafety Decl::getExplicitSafety() const {
         return ExplicitSafety::Unsafe;
   }
 
-  // If this is a pattern binding declaration, check whether the first
-  // variable is @unsafe.
+  // If this is a pattern binding declaration, check whether there is a
+  // safety-related attribute on the first variable we find.
   if (auto patternBinding = dyn_cast<PatternBindingDecl>(this)) {
-    if (auto var = patternBinding->getSingleVar())
-      return var->getExplicitSafety();
+    for (auto index : range(patternBinding->getNumPatternEntries()))
+      if (auto var = patternBinding->getAnchoringVarDecl(index))
+        return var->getExplicitSafety();
   }
 
   return ExplicitSafety::Unspecified;

test/Unsafe/safe.swift

@@ -252,11 +252,11 @@ func testUnsafeLHS() {
 
 @safe
 struct UnsafeWrapTest {
-  @unsafe var pointer: UnsafeMutablePointer<Int>?
+  var pointer: UnsafeMutablePointer<Int>?
 
   func test() {
     if let pointer { // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe'}}{{19-19= = unsafe pointer}}
-      // expected-note@-1{{reference to unsafe property 'pointer'}}
+      // expected-note@-1{{reference to property 'pointer' involves unsafe type 'UnsafeMutablePointer<Int>'}}
       _ = unsafe pointer
     }
   }

test/Unsafe/safe_argument_suppression.swift

@@ -38,7 +38,7 @@ class NotSafeSubclass: NotSafe {
 
   ns.stillUnsafe() // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe' [StrictMemorySafety]}}
   // expected-note@-1{{reference to parameter 'ns' involves unsafe type 'NotSafe'}}
-  // expected-note@-2{{reference to unsafe instance method 'stillUnsafe()'}}
+  // expected-note@-2{{reference to instance method 'stillUnsafe()' involves unsafe type 'NotSafe'}}
 }
 
 @safe func testImpliedSafetySubclass(ns: NotSafeSubclass) {

test/Unsafe/unsafe.swift

@@ -49,7 +49,7 @@ extension ConformsToMultiP: MultiP {
   // expected-note@-1{{unsafe type 'UnsafeSuper' cannot satisfy safe associated type 'Ptr'}}
   @unsafe func f() -> UnsafeSuper {
     .init() // expected-warning{{expression uses unsafe constructs but is not marked with 'unsafe'}}
-    // expected-note@-1{{reference to unsafe initializer 'init()'}}
+    // expected-note@-1{{reference to initializer 'init()' involves unsafe type 'UnsafeSuper'}}
   }
 }
 
@@ -156,7 +156,7 @@ func testMe(
   // expected-warning@+1{{expression uses unsafe constructs but is not marked with 'unsafe'}}{{7-7=unsafe }}
   _ = unsafeVar // expected-note{{reference to unsafe var 'unsafeVar'}}
   // expected-warning@+1{{expression uses unsafe constructs but is not marked with 'unsafe'}}{{3-3=unsafe }}
-  unsafeSuper.f() // expected-note{{reference to unsafe instance method 'f()'}}
+  unsafeSuper.f() // expected-note{{reference to instance method 'f()' involves unsafe type 'UnsafeSuper'}}
   // expected-note@-1{{reference to parameter 'unsafeSuper' involves unsafe type 'UnsafeSuper'}}
 
   // expected-warning@+1{{expression uses unsafe constructs but is not marked with 'unsafe'}}{{7-7=unsafe }}