Remove restriction to C++ 20

Author: SimplyDanny

clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h

@@ -28,9 +28,6 @@ class UseDesignatedInitializersCheck : public ClangTidyCheck {
   std::optional<TraversalKind> getCheckTraversalKind() const override {
     return TK_IgnoreUnlessSpelledInSource;
   }
-  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
-    return LangOpts.CPlusPlus20;
-  }
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
 
 private:

clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst

@@ -12,7 +12,11 @@ arise when changing the order of fields.
 
 C++ 20 supports the designated initializer syntax for aggregate types.
 By applying it, we can always be sure that aggregates are constructed correctly,
-because the every variable being initialized is referenced by name.
+because every variable being initialized is referenced by name.
+
+Even when compiling in a language version older than C++ 20, depending on you compiler,
+designated initializers are potentially supported. Therefore, the check is not restricted
+to C++ 20 and older.
 
 Example:
 

clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp

@@ -1,5 +1,5 @@
-// RUN: %check_clang_tidy -std=c++20 %s modernize-use-designated-initializers %t
-// RUN: %check_clang_tidy -check-suffixes=,SINGLE-ELEMENT -std=c++20 %s modernize-use-designated-initializers %t \
+// RUN: %check_clang_tidy -std=c++17 %s modernize-use-designated-initializers %t
+// RUN: %check_clang_tidy -check-suffixes=,SINGLE-ELEMENT -std=c++17 %s modernize-use-designated-initializers %t \
 // RUN:     -- -config="{CheckOptions: [{key: modernize-use-designated-initializers.IgnoreSingleElementAggregates, value: false}]}" \
 // RUN:     --