[clang-tools-extra] [clang-tidy] add new check readability-enum-initial-value (PR #86129)

[Piotr Zegar via cfe-commits]

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@@ -0,0 +1,27 @@
+// RUN: %check_clang_tidy %s readability-enum-initial-value %t
+
+enum class EError {
+  // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: inital value in enum EError has readability issue, explicit initialization of all of enumerators
+  EError_a = 1,
+  EError_b,
+  // CHECK-FIXES: EError_b = 2,
+  EError_c = 3,
+};
+
+enum class ENone {
+  ENone_a,
+  ENone_b,
+  eENone_c,
+};
+
+enum class EFirst {
+  EFirst_a = 1,
+  EFirst_b,
+  EFirst_c,
+};
+
+enum class EAll {
+  EAll_a = 1,
+  EAll_b = 2,
+  EAll_c = 3,
+};
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PiotrZSL wrote:

add some tests with macros, like where name of enum constant is behind macro.

https://github.com/llvm/llvm-project/pull/86129