[clang-tools-extra] [clang-tidy] Add `modernize-use-if-consteval` check (PR #189743)

[Zeyi Xu via cfe-commits]

================
@@ -0,0 +1,306 @@
+// RUN: %check_clang_tidy -std=c++23-or-later %s modernize-use-if-consteval %t
+
+namespace std {
+constexpr bool is_constant_evaluated() noexcept {
+  return __builtin_is_constant_evaluated();
+}
+}
+
+namespace mine {
+constexpr bool is_constant_evaluated() noexcept {
+  return __builtin_is_constant_evaluated();
+}
+}
+
+namespace alias = std;
+
+#define ICE_CALL() std::is_constant_evaluated()
+#define IF_ICE_HEADER if (std::is_constant_evaluated())
+#define IF_ONLY if
+#define RETURN_ONE() return 1;
+#define RETURN_THREE() return 3;
+
+bool runtime_predicate();
+
+int direct() {
+  if (std::is_constant_evaluated())
+    return 1;
+  else
+    return 2;
+  // CHECK-MESSAGES: :[[@LINE-4]]:7: warning: use 'if consteval' instead of checking 'std::is_constant_evaluated()' [modernize-use-if-consteval]
+  // CHECK-FIXES:      if consteval {
+  // CHECK-FIXES-NEXT:   return 1;
+  // CHECK-FIXES-NEXT: } else {
+  // CHECK-FIXES-NEXT:   return 2;
+  // CHECK-FIXES-NEXT: }
+}
+
+int direct_global() {
+  if (::std::is_constant_evaluated()) {
+    return 1;
+  }
+  return 2;
+  // CHECK-MESSAGES: :[[@LINE-4]]:7: warning: use 'if consteval' instead of checking 'std::is_constant_evaluated()' [modernize-use-if-consteval]
----------------
zeyi2 wrote:

```suggestion
  // CHECK-MESSAGES: :[[@LINE-4]]:7: warning: use 'if consteval' instead of checking 'std::is_constant_evaluated()'
```

Same as below :)

https://github.com/llvm/llvm-project/pull/189743