[clang-tools-extra] [clang-tidy] Add readability-use-builtin-literals check (PR #76065)

[Piotr Zegar via cfe-commits]

================
@@ -0,0 +1,105 @@
+// RUN: %check_clang_tidy %s readability-use-builtin-literals %t
+
+void warn_and_fix() {
+
+  (char16_t)U'a';
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: u'a';
+  (char32_t)u'a';
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: U'a';
+
+  (int)1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 1;
+  (unsigned int)0x1ul;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 0x1u;
+  (long int)2l;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 2L;
+  (unsigned long int)0x2lu;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 0x2uL;
+  (long long int)3ll;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 3LL;
+  (unsigned long long int)0x3llu;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 0x3uLL;
+
+  (double)1.f;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 1.;
+  (float)2.;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 2.f;
+  (long double)3e0f;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 3e0L;
+
+  float(2.);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 2.f;
+  double{2.};
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 2.;
+
+  static_cast<double>(2.f);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 2.;
+
+  reinterpret_cast<int>(1);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in literal instead of explicit cast [readability-use-builtin-literals]
+  // CHECK-FIXES: 1;
+}
+
+#define OPSHIFT ((unsigned)27)
+#define OCHAR (2LU<<OPSHIFT)
+#define OPSHIFT2 (27)
+#define OCHAR2 (2LU<<(unsigned)OPSHIFT2)
+#define SUBT unsigned
+#define OCHAR3 (2LU<<(SUBT)27)
+#define SUBT2 char
+#define OCHAR4 (2LU<<(SUBT2)'a')
+
+void warn_and_recommend_fix() {
+
+  OPSHIFT;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in 'u' suffix instead of explicit cast to 'unsigned int' [readability-use-builtin-literals]
+  OCHAR;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in 'u' suffix instead of explicit cast to 'unsigned int' [readability-use-builtin-literals]
+  OCHAR2;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in 'u' suffix instead of explicit cast to 'unsigned int' [readability-use-builtin-literals]
+  OCHAR3;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in 'u' suffix instead of explicit cast to 'unsigned int' [readability-use-builtin-literals]
+  OCHAR4;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use built-in '' prefix instead of explicit cast to 'char' [readability-use-builtin-literals]
+}
+
+#define INT_MAX 2147483647
+#define MAXCOL 2
+
+#ifdef CHECKED
+#define SUINT int
+#else
+#define SUINT unsigned
+#endif
+
+template <typename T>
+T f() {
+  return T(1);
+}
+
+int no_warn() {
+
+(void)0;
+(unsigned*)0;
+
+static_cast<unsigned>(INT_MAX);
+(unsigned)MAXCOL;
+
+(SUINT)31;
+
+return f<int>();
+}
----------------
PiotrZSL wrote:

Missing test for `size_t` and lack of warning & fix.

https://github.com/llvm/llvm-project/pull/76065