[clang] [clang-format] Add an option to format numeric literal case (PR #151590)

[via cfe-commits]

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@@ -0,0 +1,176 @@
+//===--- NumericLiteralCaseFixer.cpp ----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements NumericLiteralCaseFixer that standardizes character
+/// case within numeric literals.
+///
+//===----------------------------------------------------------------------===//
+
+#include "NumericLiteralCaseFixer.h"
+#include "NumericLiteralInfo.h"
+
+#include "llvm/ADT/StringExtras.h"
+
+#include <algorithm>
+
+namespace clang {
+namespace format {
+
+static bool isNumericLiteralCaseFixerNeeded(const FormatStyle &Style) {
+  // Check if language is supported.
+  switch (Style.Language) {
+  case FormatStyle::LK_C:
+  case FormatStyle::LK_Cpp:
+  case FormatStyle::LK_ObjC:
+  case FormatStyle::LK_CSharp:
+  case FormatStyle::LK_Java:
+  case FormatStyle::LK_JavaScript:
+    break;
+  default:
+    return false;
+  }
+
+  // Check if style options are set.
+  const auto &Option = Style.NumericLiteralCase;
+  const auto Leave = FormatStyle::NLCS_Leave;
+  return Option.Prefix != Leave || Option.HexDigit != Leave ||
+         Option.ExponentLetter != Leave || Option.Suffix != Leave;
+}
+
+static std::string
+transformComponent(StringRef Component,
+                   FormatStyle::NumericLiteralComponentStyle ConfigValue) {
+  switch (ConfigValue) {
+  case FormatStyle::NLCS_Upper:
+    return Component.upper();
+  case FormatStyle::NLCS_Lower:
+    return Component.lower();
+  default:
+    // Covers FormatStyle::NLCS_Leave.
+    return Component.str();
+  }
+}
+
+/// Test if Suffix matches a C++ literal reserved by the library.
+/// Matches against all suffixes reserved in the C++23 standard.
+static bool matchesReservedSuffix(StringRef Suffix) {
+  static constexpr std::array<StringRef, 11> SortedReservedSuffixes = {
+      "d", "h", "i", "if", "il", "min", "ms", "ns", "s", "us", "y"};
----------------
owenca wrote:

```suggestion
      "d", "h", "i", "if", "il", "min", "ms", "ns", "s", "us", "y",
  };
```

https://github.com/llvm/llvm-project/pull/151590