[llvm] r289040 - Improve format member detection in llvm::formatv
Pavel Labath via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 8 03:31:22 PST 2016
Author: labath
Date: Thu Dec 8 05:31:19 2016
New Revision: 289040
URL: http://llvm.org/viewvc/llvm-project?rev=289040&view=rev
Log:
Improve format member detection in llvm::formatv
Summary:
The existing detection of a format member function has a couple of deficiencies:
- the member function does not get detected if one calls formatv with an lvalue,
because the template parameter gets deduced as T&, which fails the is_class
check.
- it also did not work if the function was called with a const variable because
the template parameter would get deduced as const T&, again failing the
is_class check.
This fixes the problem by stripping the references in the uses_format_member
template, to make sure the type is correctly detected as class. It also provides
specializations of the has_FormatMember template for const and non-const members
of the types in order to enable declaring the format member as a "const"
function. I have added tests that verify that formatv can be now called in these
scenarios. As some scenarios could not be verified at runtime (e.g. making sure
that calling a non-const format member on a const object does *not* compile), I
have also added some static_asserts which test the behaviour of the template
classes used internally by formatv().
Reviewers: zturner
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D27525
Modified:
llvm/trunk/include/llvm/Support/FormatVariadicDetails.h
llvm/trunk/unittests/Support/FormatVariadicTest.cpp
Modified: llvm/trunk/include/llvm/Support/FormatVariadicDetails.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/FormatVariadicDetails.h?rev=289040&r1=289039&r2=289040&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/FormatVariadicDetails.h (original)
+++ llvm/trunk/include/llvm/Support/FormatVariadicDetails.h Thu Dec 8 05:31:19 2016
@@ -56,6 +56,7 @@ template <typename T> class missing_form
//
// void format(raw_ostream &, StringRef);
//
+// It is assumed T is a non-reference type.
template <class T, class Enable = void> class has_FormatMember {
public:
static bool const value = false;
@@ -63,8 +64,11 @@ public:
template <class T>
class has_FormatMember<T,
- typename std::enable_if<std::is_class<T>::value>::type> {
- using Signature_format = void (T::*)(llvm::raw_ostream &S, StringRef Options);
+ typename std::enable_if<std::is_class<T>::value &&
+ std::is_const<T>::value>::type> {
+ using CleanT = typename std::remove_volatile<T>::type;
+ using Signature_format = void (CleanT::*)(llvm::raw_ostream &S,
+ StringRef Options) const;
template <typename U>
static char test2(SameType<Signature_format, &U::format> *);
@@ -72,7 +76,25 @@ class has_FormatMember<T,
template <typename U> static double test2(...);
public:
- static bool const value = (sizeof(test2<T>(nullptr)) == 1);
+ static bool const value = (sizeof(test2<CleanT>(nullptr)) == 1);
+};
+
+template <class T>
+class has_FormatMember<
+ T, typename std::enable_if<std::is_class<T>::value &&
+ !std::is_const<T>::value>::type> {
+ using CleanT = typename std::remove_cv<T>::type;
+ using Signature_format = void (CleanT::*)(llvm::raw_ostream &S,
+ StringRef Options);
+
+ template <typename U>
+ static char test2(SameType<Signature_format, &U::format> *);
+
+ template <typename U> static double test2(...);
+
+public:
+ static bool const value =
+ (sizeof(test2<CleanT>(nullptr)) == 1) || has_FormatMember<const T>::value;
};
// Test if format_provider<T> is defined on T and contains a member function
@@ -98,15 +120,18 @@ public:
// based format() invocation.
template <typename T>
struct uses_format_member
- : public std::integral_constant<bool, has_FormatMember<T>::value> {};
+ : public std::integral_constant<
+ bool,
+ has_FormatMember<typename std::remove_reference<T>::type>::value> {};
// Simple template that decides whether a type T should use the format_provider
// based format() invocation. The member function takes priority, so this test
// will only be true if there is not ALSO a format member.
template <typename T>
struct uses_format_provider
- : public std::integral_constant<bool, !has_FormatMember<T>::value &&
- has_FormatProvider<T>::value> {};
+ : public std::integral_constant<
+ bool, !uses_format_member<T>::value && has_FormatProvider<T>::value> {
+};
// Simple template that decides whether a type T has neither a member-function
// nor format_provider based implementation that it can use. Mostly used so
@@ -114,8 +139,9 @@ struct uses_format_provider
// implementation can be located.
template <typename T>
struct uses_missing_provider
- : public std::integral_constant<bool, !has_FormatMember<T>::value &&
- !has_FormatProvider<T>::value> {};
+ : public std::integral_constant<bool,
+ !uses_format_member<T>::value &&
+ !uses_format_provider<T>::value> {};
template <typename T>
typename std::enable_if<uses_format_member<T>::value,
Modified: llvm/trunk/unittests/Support/FormatVariadicTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/FormatVariadicTest.cpp?rev=289040&r1=289039&r2=289040&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/FormatVariadicTest.cpp (original)
+++ llvm/trunk/unittests/Support/FormatVariadicTest.cpp Thu Dec 8 05:31:19 2016
@@ -13,6 +13,35 @@
using namespace llvm;
+// Compile-time tests for the uses_format_member template
+namespace {
+struct ConstFormat {
+ void format(raw_ostream &OS, StringRef Opt) const { OS << "ConstFormat"; }
+};
+
+struct Format {
+ void format(raw_ostream &OS, StringRef Opt) { OS << "Format"; }
+};
+
+using detail::uses_format_member;
+
+static_assert(uses_format_member<Format>::value, "");
+static_assert(uses_format_member<Format &>::value, "");
+static_assert(uses_format_member<Format &&>::value, "");
+static_assert(not uses_format_member<const Format>::value, "");
+static_assert(not uses_format_member<const Format &>::value, "");
+static_assert(not uses_format_member<const volatile Format>::value, "");
+static_assert(not uses_format_member<const volatile Format &>::value, "");
+
+static_assert(uses_format_member<ConstFormat>::value, "");
+static_assert(uses_format_member<ConstFormat &>::value, "");
+static_assert(uses_format_member<ConstFormat &&>::value, "");
+static_assert(uses_format_member<const ConstFormat>::value, "");
+static_assert(uses_format_member<const ConstFormat &>::value, "");
+static_assert(uses_format_member<const volatile ConstFormat>::value, "");
+static_assert(uses_format_member<const volatile ConstFormat &>::value, "");
+}
+
TEST(FormatVariadicTest, EmptyFormatString) {
auto Replacements = formatv_object_base::parseFormatString("");
EXPECT_EQ(0U, Replacements.size());
@@ -511,7 +540,7 @@ TEST(FormatVariadicTest, Adapter) {
public:
explicit Negative(int N) : N(N) {}
- void format(raw_ostream &S, StringRef Options) { S << -N; }
+ void format(raw_ostream &S, StringRef Options) const { S << -N; }
};
EXPECT_EQ("-7", formatv("{0}", Negative(7)).str());
@@ -535,4 +564,27 @@ TEST(FormatVariadicTest, ImplicitConvers
SmallString<4> S2 = formatv("{0} {1}", 1, 2);
EXPECT_EQ("1 2", S2);
-}
\ No newline at end of file
+}
+
+TEST(FormatVariadicTest, FormatMember) {
+ EXPECT_EQ("Format", formatv("{0}", Format()).str());
+
+ Format var;
+ EXPECT_EQ("Format", formatv("{0}", var).str());
+ EXPECT_EQ("Format", formatv("{0}", std::move(var)).str());
+
+ // Not supposed to compile
+ // const Format cvar{};
+ // EXPECT_EQ("Format", formatv("{0}", cvar).str());
+}
+
+TEST(FormatVariadicTest, FormatMemberConst) {
+ EXPECT_EQ("ConstFormat", formatv("{0}", ConstFormat()).str());
+
+ ConstFormat var;
+ EXPECT_EQ("ConstFormat", formatv("{0}", var).str());
+ EXPECT_EQ("ConstFormat", formatv("{0}", std::move(var)).str());
+
+ const ConstFormat cvar{};
+ EXPECT_EQ("ConstFormat", formatv("{0}", cvar).str());
+}
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