[SE-0458] Suppress "no unsafe operations" warnings outside of strict mode

lib/Sema/TypeCheckEffects.cpp

@@ -4309,7 +4309,8 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         Ctx.Diags.diagnose(S->getForLoc(), diag::for_unsafe_without_unsafe)
           .fixItInsert(insertionLoc, "unsafe ");
       }
-    } else if (S->getUnsafeLoc().isValid()) {
+    } else if (S->getUnsafeLoc().isValid() &&
+               Ctx.LangOpts.hasFeature(Feature::StrictMemorySafety)) {
       // Extraneous "unsafe" on the sequence.
       Ctx.Diags.diagnose(S->getUnsafeLoc(), diag::no_unsafe_in_unsafe_for)
         .fixItRemove(S->getUnsafeLoc());
@@ -4343,6 +4344,9 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
   }
 
   void diagnoseRedundantUnsafe(UnsafeExpr *E) const {
+    if (!Ctx.LangOpts.hasFeature(Feature::StrictMemorySafety))
+      return;
+
     if (auto *SVE = SingleValueStmtExpr::tryDigOutSingleValueStmtExpr(E)) {
       // For an if/switch expression, produce a tailored warning.
       Ctx.Diags.diagnose(E->getUnsafeLoc(),
@@ -4351,6 +4355,7 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         .highlight(E->getUnsafeLoc());
       return;
     }
+
     Ctx.Diags.diagnose(E->getUnsafeLoc(), diag::no_unsafe_in_unsafe);
   }
 

test/Unsafe/unsafe_nonstrict.swift

@@ -0,0 +1,18 @@
+// RUN: %target-typecheck-verify-swift -print-diagnostic-groups
+
+@unsafe func unsafeFunc() { }
+
+@unsafe
+struct UnsafeType { }
+
+protocol P { }
+
+struct X: @unsafe P { }
+
+func acceptP<T: P>(_: T) { }
+
+func testItAll(ut: UnsafeType, x: X, i: Int) {
+  _ = unsafe ut
+  unsafe acceptP(x)
+  _ = unsafe i
+}