[CodeStyle] fix c++17-extensions warning on macos (#49017)

* fix c++17-extensions warning on macos

* fix type

fix c++17-extensions warning on macos

fix c++17-extensions warning on macos

cmake/flags.cmake

@@ -220,7 +220,8 @@ if(APPLE)
       -Werror=uninitialized
       -Werror=tautological-constant-out-of-range-compare
       -Werror=literal-conversion
-      -Werror=pragma-pack)
+      -Werror=pragma-pack
+      -Werror=c++17-extensions)
 endif()
 
 if(WITH_HETERPS AND WITH_PSLIB)

paddle/phi/kernels/cpu/viterbi_decode_kernel.cc

@@ -110,7 +110,7 @@ struct Gather {
 
 template <typename Context,
           template <typename InT, typename OutT>
-          typename CompareFunctor,
+          class CompareFunctor,
           typename T>
 struct GetMask {
   void operator()(const Context& dev_ctx,
@@ -124,7 +124,7 @@ struct GetMask {
 
 template <typename Context,
           template <typename T>
-          typename BinaryFunctor,
+          class BinaryFunctor,
           typename T>
 struct BinaryOperation {
   void operator()(const Context& dev_ctx,

paddle/phi/kernels/strings/strings_lower_upper_kernel.h

@@ -94,7 +94,7 @@ struct AsciiCaseConverter {
 
 template <typename DeviceContext,
           template <typename DeviceContextT>
-          typename CharConverter>
+          class CharConverter>
 struct UTF8CaseConverter {
   void operator()(const DeviceContext& dev_ctx,
                   const pstring* in,