[region-isolation] Make "unknown pattern error" always an error.

This shows an actual issue with the compiler where semantically we should crash.
Rather than crashing (due to the broken invariants), we emit this error so that
the user gets a nice error message at the problem place and can work around it
instead of just getting a mysterious crash.

Previously, we were making this a warning in swift 5 mode... but given the
issues, it makes sense to emit an error diagnostic so we get the feedback and
the user cannot ship the code.

rdar://131482934

Author: gottesmm

lib/SILOptimizer/Mandatory/TransferNonSendable.cpp

@@ -158,6 +158,23 @@ static Expr *inferArgumentExprFromApplyExpr(ApplyExpr *sourceApply,
 //                             MARK: Diagnostics
 //===----------------------------------------------------------------------===//
 
+/// Emit the "unknown pattern error" at the SILLocation of \p inst.
+static void diagnoseUnknownPatternError(SILInstruction *inst) {
+  if (shouldAbortOnUnknownPatternMatchError()) {
+    llvm::report_fatal_error(
+        "RegionIsolation: Aborting on unknown pattern match error");
+  }
+
+  auto &ctx = inst->getFunction()->getASTContext();
+  auto loc = inst->getLoc().getSourceLoc();
+
+  ctx.Diags.diagnose(loc, diag::regionbasedisolation_unknown_pattern);
+}
+
+static void diagnoseUnknownPatternError(Operand *op) {
+  diagnoseUnknownPatternError(op->getUser());
+}
+
 template <typename... T, typename... U>
 static InFlightDiagnostic diagnoseError(ASTContext &context, SourceLoc loc,
                                         Diag<T...> diag, U &&...args) {
@@ -732,14 +749,7 @@ class UseAfterTransferDiagnosticEmitter {
   }
 
   void emitUnknownPatternError() {
-    if (shouldAbortOnUnknownPatternMatchError()) {
-      llvm::report_fatal_error(
-          "RegionIsolation: Aborting on unknown pattern match error");
-    }
-
-    diagnoseError(transferOp->getUser(),
-                  diag::regionbasedisolation_unknown_pattern)
-        .limitBehaviorIf(getBehaviorLimit());
+    diagnoseUnknownPatternError(transferOp->getUser());
   }
 
 private:
@@ -1160,12 +1170,7 @@ void TransferNonSendableImpl::emitUseAfterTransferDiagnostics() {
     // tells the user to file a bug. This importantly ensures that we can
     // guarantee that we always find the require if we successfully compile.
     if (!didEmitRequireNote) {
-      if (shouldAbortOnUnknownPatternMatchError()) {
-        llvm::report_fatal_error(
-            "RegionIsolation: Aborting on unknown pattern match error");
-      }
-
-      diagnoseError(transferOp, diag::regionbasedisolation_unknown_pattern);
+      diagnoseUnknownPatternError(transferOp);
       continue;
     }
 
@@ -1227,14 +1232,7 @@ class TransferNonTransferrableDiagnosticEmitter {
   }
 
   void emitUnknownPatternError() {
-    if (shouldAbortOnUnknownPatternMatchError()) {
-      llvm::report_fatal_error(
-          "RegionIsolation: Aborting on unknown pattern match error");
-    }
-
-    diagnoseError(getOperand()->getUser(),
-                  diag::regionbasedisolation_unknown_pattern)
-        .limitBehaviorIf(getBehaviorLimit());
+    diagnoseUnknownPatternError(getOperand()->getUser());
   }
 
   void emitUnknownUse(SILLocation loc) {
@@ -1727,14 +1725,7 @@ class InOutSendingNotDisconnectedDiagnosticEmitter {
   }
 
   void emitUnknownPatternError() {
-    if (shouldAbortOnUnknownPatternMatchError()) {
-      llvm::report_fatal_error(
-          "RegionIsolation: Aborting on unknown pattern match error");
-    }
-
-    diagnoseError(info.functionExitingInst,
-                  diag::regionbasedisolation_unknown_pattern)
-        .limitBehaviorIf(getBehaviorLimit());
+    diagnoseUnknownPatternError(info.functionExitingInst);
   }
 
   void emit();
@@ -1994,13 +1985,7 @@ struct DiagnosticEvaluator final
   }
 
   void handleUnknownCodePattern(const PartitionOp &op) const {
-    if (shouldAbortOnUnknownPatternMatchError()) {
-      llvm::report_fatal_error(
-          "RegionIsolation: Aborting on unknown pattern match error");
-    }
-
-    diagnoseError(op.getSourceInst(),
-                  diag::regionbasedisolation_unknown_pattern);
+    diagnoseUnknownPatternError(op.getSourceInst());
   }
 
   bool isActorDerived(Element element) const {