[move-only] Eliminate dead field.

Originally this was a method to determine if we had emitted a diagnostic when
running our gather visitor. It was pretty footgunny since one could easily
forget to set it. Instead of doing that, we now maintain a counter in the
diagnostic emitter that counts how many diagnostics we have emitted and use that
to determine if during the walk if we emitted any additional diagnostics.

Author: gottesmm

lib/SILOptimizer/Mandatory/MoveOnlyAddressCheckerUtils.cpp

@@ -1354,7 +1354,6 @@ struct GatherUsesVisitor final : public TransitiveAddressWalker {
   MoveOnlyAddressCheckerPImpl &moveChecker;
   UseState &useState;
   MarkMustCheckInst *markedValue;
-  bool emittedEarlyDiagnostic = false;
   DiagnosticEmitter &diagnosticEmitter;
 
   // Pruned liveness used to validate that load [take]/load [copy] can be
@@ -1529,14 +1528,13 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
       if (isa<ProjectBoxInst>(stripAccessMarkers(markedValue->getOperand()))) {
         LLVM_DEBUG(llvm::dbgs()
                    << "Found mark must check [nocopy] use of escaping box: " << *user);
-        diagnosticEmitter.emitAddressEscapingClosureCaptureLoadedAndConsumed(markedValue);
-        emittedEarlyDiagnostic = true;
+        diagnosticEmitter.emitAddressEscapingClosureCaptureLoadedAndConsumed(
+            markedValue);
         return true;
       }
       LLVM_DEBUG(llvm::dbgs()
                  << "Found mark must check [nocopy] error: " << *user);
       diagnosticEmitter.emitAddressDiagnosticNoCopy(markedValue, copyAddr);
-      emittedEarlyDiagnostic = true;
       return true;
     }
 
@@ -1592,15 +1590,13 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
                  .didEmitCheckerDoesntUnderstandDiagnostic());
       LLVM_DEBUG(llvm::dbgs()
                  << "Failed to perform borrow to destructure transform!\n");
-      emittedEarlyDiagnostic = true;
       return false;
     }
 
     // If we emitted an error diagnostic, do not transform further and instead
     // mark that we emitted an early diagnostic and return true.
     if (numDiagnostics != moveChecker.diagnosticEmitter.getDiagnosticCount()) {
       LLVM_DEBUG(llvm::dbgs() << "Emitting borrow to destructure error!\n");
-      emittedEarlyDiagnostic = true;
       return true;
     }
 
@@ -1621,7 +1617,6 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
     if (numDiagnostics != moveChecker.diagnosticEmitter.getDiagnosticCount()) {
       LLVM_DEBUG(llvm::dbgs()
                  << "Emitting destructure through deinit error!\n");
-      emittedEarlyDiagnostic = true;
       return true;
     }
 
@@ -1646,7 +1641,6 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
           moveChecker.diagnosticEmitter
               .emitAddressEscapingClosureCaptureLoadedAndConsumed(markedValue);
         }
-        emittedEarlyDiagnostic = true;
         return true;
       }
 
@@ -1660,7 +1654,6 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
 
       if (checkForExclusivityHazards(li)) {
         LLVM_DEBUG(llvm::dbgs() << "Found exclusivity violation?!\n");
-        emittedEarlyDiagnostic = true;
         return true;
       }
 
@@ -1693,7 +1686,6 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
       // succeeded.
       // Otherwise, emit the diagnostic.
       moveChecker.diagnosticEmitter.emitObjectOwnedDiagnostic(markedValue);
-      emittedEarlyDiagnostic = true;
       LLVM_DEBUG(llvm::dbgs() << "Emitted early object level diagnostic.\n");
       return true;
     }
@@ -1702,7 +1694,6 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
       LLVM_DEBUG(llvm::dbgs() << "Found potential borrow inst: " << *user);
       if (checkForExclusivityHazards(li)) {
         LLVM_DEBUG(llvm::dbgs() << "Found exclusivity violation?!\n");
-        emittedEarlyDiagnostic = true;
         return true;
       }
 
@@ -1751,7 +1742,6 @@ bool GatherUsesVisitor::visitUse(Operand *op) {
         moveChecker.diagnosticEmitter
             .emitAddressEscapingClosureCaptureLoadedAndConsumed(markedValue);
       }
-      emittedEarlyDiagnostic = true;
       return true;
     }