mark some switches as covered (NFCI)

Unfortunately, MSVC does not detect covered switches as clang.  Mark
some of the switches as covered to avoid an unnecessary warning from
MSVC.

Author: compnerd

include/swift/SIL/ApplySite.h

@@ -377,6 +377,7 @@ class ApplySite {
     case SILArgumentConvention::Indirect_Out:
       llvm_unreachable("partial_apply cannot have an @out operand");
     }
+    llvm_unreachable("covered switch");
   }
 
   /// Return true if 'self' is an applied argument.
@@ -454,7 +455,9 @@ class ApplySite {
     case ApplySiteKind::PartialApplyInst:
       return ApplyOptions();
     }
+    llvm_unreachable("covered switch");
   }
+
   /// Return whether the given apply is of a formally-throwing function
   /// which is statically known not to throw.
   bool isNonThrowing() const {

include/swift/SIL/DebugUtils.h

@@ -290,6 +290,7 @@ struct DebugVarCarryingInst {
     case Kind::AllocBox:
       return cast<AllocBoxInst>(inst)->getDecl();
     }
+    llvm_unreachable("covered switch");
   }
 
   Optional<SILDebugVariable> getVarInfo() const {
@@ -305,6 +306,7 @@ struct DebugVarCarryingInst {
     case Kind::AllocBox:
       return cast<AllocBoxInst>(inst)->getVarInfo();
     }
+    llvm_unreachable("covered switch");
   }
 };
 

include/swift/SIL/DynamicCasts.h

@@ -168,6 +168,7 @@ struct SILDynamicCastInst {
     return SILDynamicCastInst(cast<ID>(inst));
 #include "swift/SIL/SILNodes.def"
     }
+    llvm_unreachable("covered switch");
   }
 
   SILDynamicCastKind getKind() const {
@@ -359,6 +360,7 @@ struct SILDynamicCastInst {
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       return cast<UnconditionalCheckedCastValueInst>(inst)->getSourceLoweredType();
     }
+    llvm_unreachable("covered switch");
   }
 
   CanType getTargetFormalType() const {

include/swift/SIL/MemAccessUtils.h

@@ -464,6 +464,7 @@ class AccessedStorage {
     case AccessedStorage::Tail:
       return getObject();
     }
+    llvm_unreachable("covered switch");
   }
 
   /// Visit all access roots. If any roots are visited then the original memory

include/swift/SIL/OwnershipUtils.h

@@ -752,6 +752,7 @@ struct InteriorPointerOperand {
       return InteriorPointerOperand(op, kind);
     }
     }
+    llvm_unreachable("covered switch");
   }
 
   /// Return the end scope of all borrow introducers of the parent value of this
@@ -1035,6 +1036,7 @@ struct OwnedValueIntroducer {
     case OwnedValueIntroducerKind::AllocRefInit:
       return false;
     }
+    llvm_unreachable("covered switch");
   }
 
   bool operator==(const OwnedValueIntroducer &other) const {

include/swift/SIL/SILLocation.h

@@ -207,6 +207,7 @@ class SILLocation {
     case FilenameAndLocationKind:
       llvm_unreachable("location type has no AST node");
     }
+    llvm_unreachable("covered switch");
   }
 
   /// Returns true if the location has a separate AST node for debugging.
@@ -300,6 +301,7 @@ class SILLocation {
     case FilenameAndLocationKind: return storage.filePositionLoc == nullptr;;
     case SourceLocKind:           return storage.sourceLoc.isInvalid();
     }
+    llvm_unreachable("covered switch");
   }
   explicit operator bool() const { return !isNull(); }
 
@@ -313,6 +315,7 @@ class SILLocation {
     case FilenameAndLocationKind:
       return false;
     }
+    llvm_unreachable("covered switch");
   }
 
   /// Returns true if this location came from a SIL file.

include/swift/SIL/SILValue.h

@@ -875,6 +875,7 @@ inline OwnershipConstraint OperandOwnership::getOwnershipConstraint() {
   case OperandOwnership::Reborrow:
     return {OwnershipKind::Guaranteed, UseLifetimeConstraint::LifetimeEnding};
   }
+  llvm_unreachable("covered switch");
 }
 
 /// Return true if this use can accept Unowned values.
@@ -900,6 +901,7 @@ inline bool canAcceptUnownedValue(OperandOwnership operandOwnership) {
   case OperandOwnership::Reborrow:
     return false;
   }
+  llvm_unreachable("covered switch");
 }
 
 /// Return the OperandOwnership for a forwarded operand when the forwarding

lib/Basic/LangOptions.cpp

@@ -391,6 +391,7 @@ llvm::StringRef swift::getFeatureName(Feature feature) {
   case Feature::FeatureName: return #FeatureName;
 #include "swift/Basic/Features.def"
   }
+  llvm_unreachable("covered switch");
 }
 
 DiagnosticBehavior LangOptions::getAccessNoteFailureLimit() const {
@@ -405,4 +406,5 @@ DiagnosticBehavior LangOptions::getAccessNoteFailureLimit() const {
   case AccessNoteDiagnosticBehavior::ErrorOnFailureRemarkOnSuccess:
     return DiagnosticBehavior::Error;
   }
+  llvm_unreachable("covered switch");
 }

lib/IRGen/Callee.h

@@ -228,6 +228,7 @@ namespace irgen {
           // future.
           return false;
         }
+        llvm_unreachable("covered switch");
       }
 
       friend bool operator==(Kind lhs, Kind rhs) {

lib/IRGen/GenClass.cpp

@@ -2712,7 +2712,7 @@ FunctionPointer irgen::emitVirtualMethodValue(IRGenFunction &IGF,
                                       signature);
   }
   }
-  
+  llvm_unreachable("covered switch");
 }
 
 FunctionPointer