aaron.ballman created this revision.
aaron.ballman added reviewers: sbenza, klimek.
aaron.ballman added a subscriber: cfe-commits.
Herald added a subscriber: klimek.
ASTMatchersInternal uses a custom type trait to determine the presence or
absence of a getDecl member function. While the current implementation works,
it requires compiler-specific hackery to work around some MSVC issues. This
patch replaces the original implementation with one that requires less
compiler-specific work.
http://reviews.llvm.org/D17575
Files:
include/clang/ASTMatchers/ASTMatchersInternal.h
Index: include/clang/ASTMatchers/ASTMatchersInternal.h
===================================================================
--- include/clang/ASTMatchers/ASTMatchersInternal.h
+++ include/clang/ASTMatchers/ASTMatchersInternal.h
@@ -569,32 +569,21 @@
return false;
}
-// Metafunction to determine if type T has a member called
-// getDecl.
-#if defined(_MSC_VER) && !defined(__clang__)
-// For MSVC, we use a weird nonstandard __if_exists statement, as it
-// is not standards-conformant enough to properly compile the standard
-// code below. (At least up through MSVC 2015 require this workaround)
-template <typename T> struct has_getDecl {
- __if_exists(T::getDecl) {
- enum { value = 1 };
- }
- __if_not_exists(T::getDecl) {
- enum { value = 0 };
- }
+// Metafunction to determine if type T has a member called getDecl.
+template <typename Ty>
+class has_getDecl {
+ typedef char yes[1];
+ typedef char no[2];
+
+ template <typename Inner>
+ static yes& test(Inner *I, decltype(I->getDecl()) * = nullptr);
+
+ template <typename>
+ static no& test(...);
+
+public:
+ static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
};
-#else
-// There is a default template inheriting from "false_type". Then, a
-// partial specialization inherits from "true_type". However, this
-// specialization will only exist when the call to getDecl() isn't an
-// error -- it vanishes by SFINAE when the member doesn't exist.
-template <typename> struct type_sink_to_void { typedef void type; };
-template <typename T, typename = void> struct has_getDecl : std::false_type {};
-template <typename T>
-struct has_getDecl<
- T, typename type_sink_to_void<decltype(std::declval<T>().getDecl())>::type>
- : std::true_type {};
-#endif
/// \brief Matches overloaded operators with a specific name.
///
Index: include/clang/ASTMatchers/ASTMatchersInternal.h
===================================================================
--- include/clang/ASTMatchers/ASTMatchersInternal.h
+++ include/clang/ASTMatchers/ASTMatchersInternal.h
@@ -569,32 +569,21 @@
return false;
}
-// Metafunction to determine if type T has a member called
-// getDecl.
-#if defined(_MSC_VER) && !defined(__clang__)
-// For MSVC, we use a weird nonstandard __if_exists statement, as it
-// is not standards-conformant enough to properly compile the standard
-// code below. (At least up through MSVC 2015 require this workaround)
-template <typename T> struct has_getDecl {
- __if_exists(T::getDecl) {
- enum { value = 1 };
- }
- __if_not_exists(T::getDecl) {
- enum { value = 0 };
- }
+// Metafunction to determine if type T has a member called getDecl.
+template <typename Ty>
+class has_getDecl {
+ typedef char yes[1];
+ typedef char no[2];
+
+ template <typename Inner>
+ static yes& test(Inner *I, decltype(I->getDecl()) * = nullptr);
+
+ template <typename>
+ static no& test(...);
+
+public:
+ static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
};
-#else
-// There is a default template inheriting from "false_type". Then, a
-// partial specialization inherits from "true_type". However, this
-// specialization will only exist when the call to getDecl() isn't an
-// error -- it vanishes by SFINAE when the member doesn't exist.
-template <typename> struct type_sink_to_void { typedef void type; };
-template <typename T, typename = void> struct has_getDecl : std::false_type {};
-template <typename T>
-struct has_getDecl<
- T, typename type_sink_to_void<decltype(std::declval<T>().getDecl())>::type>
- : std::true_type {};
-#endif
/// \brief Matches overloaded operators with a specific name.
///
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