[NFC] Mark Expected<T>::assertIsChecked() as const

[xndcn]

Summary

Some const methods of Expected<T> invoke assertIsChecked(), so we should mark it as const too.

[sammccall]

LG thanks!
I guess this didn't cause problems so far because usage of const Expected is rare.

(next time please upload with full context)

llvm/unittests/Support/ErrorTest.cpp

574

Nit: unchecked (typo)

[xndcn]

@sammccall Thanks! Fixed 3 typo.

llvm/include/llvm/Support/Error.h

void fatalUncheckedExpected() const {
     } else
       dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
                 "values in success mode must still be checked prior to being "
                 "destroyed).\n";
     abort();
   }
 #endif
 
-  void assertIsChecked() {
+  void assertIsChecked() const {
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
     if (LLVM_UNLIKELY(Unchecked))
       fatalUncheckedExpected();
 #endif
   }
 
   union {
     AlignedCharArrayUnion<storage_type> TStorage;

llvm/unittests/Support/ErrorTest.cpp

 
 // Test Unchecked Expected<T> in success mode.
 // We expect this to blow up the same way Error would.
 // Test runs in debug mode only.
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
 TEST(Error, UncheckedExpectedInSuccessModeDestruction) {
   EXPECT_DEATH({ Expected<int> A = 7; },
                "Expected<T> must be checked before access or destruction.")
-    << "Unchecekd Expected<T> success value did not cause an abort().";
+      << "Unchecked Expected<T> success value did not cause an abort().";
 }
 #endif
 
 // Test Unchecked Expected<T> in success mode.
 // We expect this to blow up the same way Error would.
 // Test runs in debug mode only.
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
 TEST(Error, UncheckedExpectedInSuccessModeAccess) {
-  EXPECT_DEATH({ Expected<int> A = 7; *A; },
-               "Expected<T> must be checked before access or destruction.")
-    << "Unchecekd Expected<T> success value did not cause an abort().";
+  EXPECT_DEATH(
+      {
+        const Expected<int> A = 7;
+        *A;
+      },
+      << "Unchecked Expected<T> success value did not cause an abort().";
 }
 #endif
 
 // Test Unchecked Expected<T> in success mode.
 // We expect this to blow up the same way Error would.
 // Test runs in debug mode only.
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
 TEST(Error, UncheckedExpectedInSuccessModeAssignment) {
-  EXPECT_DEATH({ Expected<int> A = 7; A = 7; },
-               "Expected<T> must be checked before access or destruction.")
-    << "Unchecekd Expected<T> success value did not cause an abort().";
+  EXPECT_DEATH(
+      {
+        Expected<int> A = 7;
+        A = 7;
+      },
+      << "Unchecked Expected<T> success value did not cause an abort().";
 }
 #endif
 
 // Test Expected<T> in failure mode.
 TEST(Error, ExpectedInFailureMode) {
   Expected<int> A = make_error<CustomError>(42);
   EXPECT_FALSE(!!A) << "Expected with error value doesn't convert to 'false'";
   Error E = A.takeError();