On 16/08/16 12:52 +0100, Jonathan Wakely wrote:
On 10/08/16 10:50 +0300, Ville Voutilainen wrote:
diff --git a/libstdc++-v3/include/bits/basic_string.h
b/libstdc++-v3/include/bits/basic_string.h
index 59f1c64..89e2100 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -1227,9 +1227,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __n The number of characters to append from the string_view.
* @return Reference to this string.
*/
- basic_string& append(__sv_type __sv,
+ template <typename _Tp,
+ enable_if_t<is_convertible_v<const _Tp&, __sv_type>,
+ bool> = true>
+ basic_string& append(const _Tp& __svt,
size_type __pos, size_type __n = npos)
I would prefer the enable_if constraint to be on the return type, so
there is only one template parameter:
template <typename _Tp>
enable_if_t<is_convertible_v<const _Tp&, __sv_type>, basic_string&>
append(const _Tp& __svt,
size_type __pos, size_type __n = npos)
However these function templates appear to have a design problem, see
PR 77264.
This patch constrains the new overloads using:
template<typename _Tp, typename _Res>
using _If_sv = enable_if_t<
__and_<is_convertible<const _Tp&, __sv_type>,
__not_<is_convertible<const _Tp&, const _CharT*>>>::value,
_Res>;
so that anything convertible to const _CharT* goes to the same
overload as would have been chosen prior to C++17.
I'm testing this now but won't commit it until it's clear this is a
sensible resolution for LWG 2758.
commit 80e14013c4581fba08099f7a627c63cebc2a378e
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Aug 16 13:50:55 2016 +0100
PR 77264 constrain new std::basic_string overloads
PR libstdc++/77264
* include/bits/basic_string.h (operator=(__sv_type)
(append(__sv_type), assign(__sv_type), insert(size_type, __sv_type))
(replace(size_type, size_type, __sv_type))
(replace(const_iterator, const_iterator, __sv_type))
(find(__sv_type, size_type), rfind(__sv_type, size_type))
(compare(size_type, size_type, __sv_type)): Reformat.
(_If_sv): Define helper for SFINAE constaints.
(append(const _Tp&, size_type, size_type))
(assign(const _Tp&, size_type, size_type))
(insert(size_type, const _Tp&, size_type, size_type))
(replace(size_type, size_type, const _Tp&, size_type, size_type)):
Use _If_sv.
* testsuite/21_strings/basic_string/modifiers/replace/char/7.cc: Test
SFINAE constraints.
* testsuite/21_strings/basic_string/modifiers/replace/wchar_t/7.cc:
Likewise.
diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index 89e2100..68cfc99 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -709,7 +709,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @brief Set value to string constructed from a string_view.
* @param __sv A string_view.
*/
- basic_string& operator=(__sv_type __sv)
+ basic_string&
+ operator=(__sv_type __sv)
{ return this->assign(__sv); }
/**
@@ -1217,9 +1218,16 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __sv The string_view to be appended.
* @return Reference to this string.
*/
- basic_string& append(__sv_type __sv)
+ basic_string&
+ append(__sv_type __sv)
{ return this->append(__sv.data(), __sv.size()); }
+ template<typename _Tp, typename _Res>
+ using _If_sv = enable_if_t<
+ __and_<is_convertible<const _Tp&, __sv_type>,
+ __not_<is_convertible<const _Tp&, const _CharT*>>>::value,
+ _Res>;
+
/**
* @brief Append a range of characters from a string_view.
* @param __sv The string_view to be appended from.
@@ -1227,17 +1235,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __n The number of characters to append from the string_view.
* @return Reference to this string.
*/
- template <typename _Tp,
- enable_if_t<is_convertible_v<const _Tp&, __sv_type>,
- bool> = true>
- basic_string& append(const _Tp& __svt,
- size_type __pos, size_type __n = npos)
- {
- __sv_type __sv = __svt;
- return _M_append(__sv.data()
- + __sv._M_check(__pos, "basic_string::append"),
- __sv._M_limit(__pos, __n));
- }
+ template <typename _Tp>
+ _If_sv<_Tp, basic_string&>
+ append(const _Tp& __svt, size_type __pos, size_type __n = npos)
+ {
+ __sv_type __sv = __svt;
+ return _M_append(__sv.data()
+ + __sv._M_check(__pos, "basic_string::append"),
+ __sv._M_limit(__pos, __n));
+ }
#endif // C++17
/**
@@ -1386,7 +1392,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __sv The source string_view.
* @return Reference to this string.
*/
- basic_string& assign(__sv_type __sv)
+ basic_string&
+ assign(__sv_type __sv)
{ return this->assign(__sv.data(), __sv.size()); }
/**
@@ -1396,18 +1403,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __n The number of characters to assign.
* @return Reference to this string.
*/
- template <typename _Tp,
- enable_if_t<is_convertible_v<const _Tp&, __sv_type>,
- bool> = true>
- basic_string&
- assign(const _Tp& __svt,
- size_type __pos, size_type __n = npos)
- {
- __sv_type __sv = __svt;
- return _M_replace(size_type(0), this->size(), __sv.data()
- + __sv._M_check(__pos, "basic_string::assign"),
- __sv._M_limit(__pos, __n));
- }
+ template <typename _Tp>
+ _If_sv<_Tp, basic_string&>
+ assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
+ {
+ __sv_type __sv = __svt;
+ return _M_replace(size_type(0), this->size(), __sv.data()
+ + __sv._M_check(__pos, "basic_string::assign"),
+ __sv._M_limit(__pos, __n));
+ }
#endif // C++17
#if __cplusplus >= 201103L
@@ -1647,8 +1651,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __sv The string_view to insert.
* @return Reference to this string.
*/
- basic_string& insert(size_type __pos,
- __sv_type __sv)
+ basic_string&
+ insert(size_type __pos, __sv_type __sv)
{ return this->insert(__pos, __sv.data(), __sv.size()); }
/**
@@ -1660,17 +1664,16 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __n The number of characters to insert.
* @return Reference to this string.
*/
- template <typename _Tp,
- enable_if_t<is_convertible_v<const _Tp&, __sv_type>,
- bool> = true>
- basic_string& insert(size_type __pos1, const _Tp& __svt,
- size_type __pos2, size_type __n = npos)
- {
- __sv_type __sv = __svt;
- return this->replace(__pos1, size_type(0), __sv.data()
- + __sv._M_check(__pos2, "basic_string::insert"),
- __sv._M_limit(__pos2, __n));
- }
+ template <typename _Tp>
+ _If_sv<_Tp, basic_string&>
+ insert(size_type __pos1, const _Tp& __svt,
+ size_type __pos2, size_type __n = npos)
+ {
+ __sv_type __sv = __svt;
+ return this->replace(__pos1, size_type(0), __sv.data()
+ + __sv._M_check(__pos2, "basic_string::insert"),
+ __sv._M_limit(__pos2, __n));
+ }
#endif // C++17
/**
@@ -2070,8 +2073,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __sv The string_view to insert.
* @return Reference to this string.
*/
- basic_string& replace(size_type __pos, size_type __n,
- __sv_type __sv)
+ basic_string&
+ replace(size_type __pos, size_type __n, __sv_type __sv)
{ return this->replace(__pos, __n, __sv.data(), __sv.size()); }
/**
@@ -2083,18 +2086,16 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __n2 The number of characters to insert.
* @return Reference to this string.
*/
- template <typename _Tp,
- enable_if_t<is_convertible_v<const _Tp&, __sv_type>,
- bool> = true>
- basic_string& replace(size_type __pos1, size_type __n1,
- const _Tp& __svt,
- size_type __pos2, size_type __n2 = npos)
- {
- __sv_type __sv = __svt;
- return this->replace(__pos1, __n1, __sv.data()
- + __sv._M_check(__pos2, "basic_string::replace"),
- __sv._M_limit(__pos2, __n2));
- }
+ template <typename _Tp>
+ _If_sv<_Tp, basic_string&>
+ replace(size_type __pos1, size_type __n1, const _Tp& __svt,
+ size_type __pos2, size_type __n2 = npos)
+ {
+ __sv_type __sv = __svt;
+ return this->replace(__pos1, __n1, __sv.data()
+ + __sv._M_check(__pos2, "basic_string::replace"),
+ __sv._M_limit(__pos2, __n2));
+ }
/**
* @brief Replace range of characters with string_view.
@@ -2105,8 +2106,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __sv The string_view to insert from.
* @return Reference to this string.
*/
- basic_string& replace(const_iterator __i1, const_iterator __i2,
- __sv_type __sv)
+ basic_string&
+ replace(const_iterator __i1, const_iterator __i2, __sv_type __sv)
{ return this->replace(__i1 - begin(), __i2 - __i1, __sv); }
#endif // C++17
@@ -2241,8 +2242,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @return Index of start of first occurrence.
*/
size_type
- find(__sv_type __sv,
- size_type __pos = 0) const noexcept
+ find(__sv_type __sv, size_type __pos = 0) const noexcept
{ return this->find(__sv.data(), __pos, __sv.size()); }
#endif // C++17
@@ -2299,8 +2299,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @return Index of start of last occurrence.
*/
size_type
- rfind (__sv_type __sv,
- size_type __pos = npos) const noexcept
+ rfind(__sv_type __sv, size_type __pos = npos) const noexcept
{ return this->rfind(__sv.data(), __pos, __sv.size()); }
#endif // C++17
@@ -2721,11 +2720,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @return Integer < 0, 0, or > 0.
*/
int
- compare(size_type __pos, size_type __n,
- __sv_type __sv) const
- {
- return __sv_type(*this).substr(__pos, __n).compare(__sv);
- }
+ compare(size_type __pos, size_type __n, __sv_type __sv) const
+ { return __sv_type(*this).substr(__pos, __n).compare(__sv); }
/**
* @brief Compare to a string_view.
@@ -2736,17 +2732,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
* @param __n2 The number of characters to compare.
* @return Integer < 0, 0, or > 0.
*/
- template <typename _Tp,
- enable_if_t<is_convertible_v<const _Tp&, __sv_type>,
- bool> = true>
- int compare(size_type __pos1, size_type __n1,
- const _Tp& __svt,
- size_type __pos2, size_type __n2 = npos) const
- {
- __sv_type __sv = __svt;
- return __sv_type(*this)
- .substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
- }
+ template <typename _Tp>
+ _If_sv<_Tp, int>
+ compare(size_type __pos1, size_type __n1, const _Tp& __svt,
+ size_type __pos2, size_type __n2 = npos) const
+ {
+ __sv_type __sv = __svt;
+ return __sv_type(*this)
+ .substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
+ }
#endif // C++17
/**
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/char/7.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/char/7.cc
index 004b235..2a2858b 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/char/7.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/char/7.cc
@@ -47,8 +47,30 @@ test03()
VERIFY (str2 == "foofoo");
}
+// PR libstdc++/77264
+void
+test04()
+{
+ bool test __attribute__((unused)) = true;
+
+ std::string str("a");
+ char c = 'b';
+ str.replace(0, 1, &c, 1);
+ VERIFY (str[0] == 'b');
+
+ struct S {
+ operator char*() { return &c; }
+ operator std::string_view() { return "!"; }
+ char c = 'a';
+ };
+
+ str.replace(0, 1, S{}, 1);
+ VERIFY (str[0] == 'a');
+}
+
int main()
{
test03();
+ test04();
return 0;
}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/wchar_t/7.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/wchar_t/7.cc
index 88d2666..1e2505e 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/wchar_t/7.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/replace/wchar_t/7.cc
@@ -47,8 +47,30 @@ test03()
VERIFY (str2 == L"foofoo");
}
+// PR libstdc++/77264
+void
+test04()
+{
+ bool test __attribute__((unused)) = true;
+
+ std::wstring str(L"a");
+ wchar_t c = L'b';
+ str.replace(0, 1, &c, 1);
+ VERIFY (str[0] == L'b');
+
+ struct S {
+ operator wchar_t*() { return &c; }
+ operator std::wstring_view() { return L"!"; }
+ wchar_t c = L'a';
+ };
+
+ str.replace(0, 1, S{}, 1);
+ VERIFY (str[0] == L'a');
+}
+
int main()
{
test03();
+ test04();
return 0;
}
