HAVE_CXX14_CONSTEXPR is always true now

...but for safety, leave the configure.ac check in for some longer.

o3tl::array_view::max_size (include/o3tl/array_view.hxx) and
o3tl::basic_string_view::max_size (include/o3tl/string_view.hxx) started to
produce loplugin:staticmethods warnings, which I silenced by /not/ making the
functions static.  Those classes are meant to be temporary drop-in replacements
for standard classes (std::span slated for C++20, prev. std::array_view; and
std::basic_string_view, resp.), so should have the same behavior as their
standard counterparts (and making the functions static would likely cause
loplugin:staticaccess warnings at call sites).

Change-Id: If21674dbf02886f453ca447544e37b184df5a25e
Reviewed-on: https://gerrit.libreoffice.org/64768
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

10 files changed, 29 insertions, 150 deletions

diff --git a/config_host/config_global.h.in b/config_host/config_global.h.in
index 504594d0081b..605a7fe0ed9d 100644
--- a/config_host/config_global.h.in
+++ b/config_host/config_global.h.in
@@ -12,7 +12,6 @@ Any change in this header will cause a rebuild of almost everything.
 #ifndef CONFIG_GLOBAL_H
 #define CONFIG_GLOBAL_H
 
-#define HAVE_CXX14_CONSTEXPR 0
 #define HAVE_GCC_BUILTIN_ATOMIC 0
 #define HAVE_GCC_BUILTIN_FFS 0
 /* _Pragma */
diff --git a/configure.ac b/configure.ac
index 81e7d8aaaeb5..3d25986d1fae 100644
--- a/configure.ac
+++ b/configure.ac
@@ -6347,7 +6347,8 @@ return !(i != 0 && j != 0);
 AC_LANG_POP([C++])
 CXXFLAGS=$save_CXXFLAGS
 
-AC_MSG_CHECKING([whether $CXX supports C++14 constexpr])
+dnl This check can eventually be removed completely (e.g., after libreoffice-6-3 branch off):
+AC_MSG_CHECKING([that $CXX supports C++14 constexpr])
 save_CXXFLAGS=$CXXFLAGS
 CXXFLAGS="$CXXFLAGS $CXXFLAGS_CXX11"
 AC_LANG_PUSH([C++])
@@ -6375,13 +6376,9 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
         }
     };
     constexpr auto v2 = S{10}.f();
-    ]])], [cxx14_constexpr=yes], [cxx14_constexpr=no])
+    ]])], AC_MSG_RESULT([yes]), AC_MSG_ERROR([$CXX lacks required C++14 constexpr support]))
 AC_LANG_POP([C++])
 CXXFLAGS=$save_CXXFLAGS
-AC_MSG_RESULT([$cxx14_constexpr])
-if test "$cxx14_constexpr" = yes; then
-    AC_DEFINE([HAVE_CXX14_CONSTEXPR])
-fi
 
 dnl _Pragma support (may require C++11)
 if test "$GCC" = "yes" -o "$COM_IS_CLANG" = TRUE; then
diff --git a/include/o3tl/array_view.hxx b/include/o3tl/array_view.hxx
index 563821a46f6d..dd6ca7fa94c0 100644
--- a/include/o3tl/array_view.hxx
+++ b/include/o3tl/array_view.hxx
@@ -22,17 +22,10 @@
 #include <type_traits>
 #include <utility>
 
-#include <config_global.h>
 #include <rtl/string.hxx>
 #include <rtl/ustring.hxx>
 #include <sal/types.h>
 
-#if HAVE_CXX14_CONSTEXPR
-#define CONSTEXPR constexpr
-#else
-#define CONSTEXPR
-#endif
-
 namespace o3tl {
 
 #if defined _MSC_VER
@@ -64,15 +57,13 @@ public:
     constexpr array_view() noexcept : data_(nullptr), size_(0) {}
 
     template<size_type N>
-    CONSTEXPR array_view (T (&a)[N]) noexcept : data_(a), size_(N) {}
+    constexpr array_view (T (&a)[N]) noexcept : data_(a), size_(N) {}
 
-    CONSTEXPR array_view (T *a, size_type len) noexcept
+    constexpr array_view (T *a, size_type len) noexcept
         : data_(a), size_(len)
     {
-#if HAVE_CXX14_CONSTEXPR
         // not terribly sure about this, might need to relax it
         assert((a == nullptr && len == 0) || (a != nullptr && len > 0));
-#endif
     }
 
     /// Allow for assigning array_view<T> to array_view<T const> i.e.
@@ -106,25 +97,17 @@ public:
     constexpr size_type size() const noexcept { return size_; }
     constexpr size_type length() const noexcept { return size(); }
 
-#if !defined __clang__ || HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type max_size() const noexcept {
-#if defined __clang__ // avoid constexpr issues with other, older compilers
-        (void) this; // loplugin:staticmethods
-#endif
+    constexpr size_type max_size() const noexcept {
+        (void) this; // silence loplugin:staticmethods
         return npos - 1;
     }
 
     constexpr reference operator [](size_type pos) const {
-#if HAVE_CXX14_CONSTEXPR
         assert(pos < size());
-#endif
         return data_[pos];
     }
 
-    CONSTEXPR
-    reference at(size_type pos) const {
+    constexpr reference at(size_type pos) const {
         if (pos >= size()) {
             throw std::out_of_range("o3tl::array_view::at");
         }
@@ -132,22 +115,18 @@ public:
     }
 
     constexpr reference front() const {
-#if HAVE_CXX14_CONSTEXPR
         assert(!empty());
-#endif
         return operator [](0);
     }
 
     constexpr reference back() const {
-#if HAVE_CXX14_CONSTEXPR
         assert(!empty());
-#endif
         return operator [](size() - 1);
     }
 
     constexpr pointer data() const noexcept { return data_; }
 
-    CONSTEXPR void swap(array_view & s) noexcept {
+    constexpr void swap(array_view & s) noexcept {
         std::swap(data_, s.data_);
         std::swap(size_, s.size_);
     }
@@ -179,9 +158,6 @@ struct hash<o3tl::array_view<T>> {
 
 } // namespace std
 
-
-#undef CONSTEXPR
-
 #endif
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/include/o3tl/clamp.hxx b/include/o3tl/clamp.hxx
index 054de5e22517..06fa22e48cec 100644
--- a/include/o3tl/clamp.hxx
+++ b/include/o3tl/clamp.hxx
@@ -15,8 +15,6 @@
 #include <algorithm>
 #include <cassert>
 
-#include <config_global.h>
-
 // C++17 std::clamp
 
 namespace o3tl
@@ -29,9 +27,7 @@ using std::clamp;
 
 template <typename T> constexpr const T& clamp(const T& v, const T& lo, const T& hi)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(!(hi < lo));
-#endif
     return v < lo ? lo : (hi < v ? hi : v);
 }
 
diff --git a/include/o3tl/string_view.hxx b/include/o3tl/string_view.hxx
index 4da7fcf0bf0f..b605da65ac90 100644
--- a/include/o3tl/string_view.hxx
+++ b/include/o3tl/string_view.hxx
@@ -22,7 +22,6 @@
 #include <type_traits>
 #include <utility>
 
-#include <config_global.h>
 #include <rtl/string.hxx>
 #include <rtl/ustring.hxx>
 #include <sal/types.h>
@@ -174,10 +173,7 @@ public:
 
     constexpr basic_string_view(basic_string_view const &) noexcept = default;
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    basic_string_view & operator =(basic_string_view const & other) noexcept = default;
+    constexpr basic_string_view & operator =(basic_string_view const & other) noexcept = default;
 
     // The various character types are handled below in the "LO specifics, to
     // make up for traits::length not necessarily being constexpr yet for
@@ -217,29 +213,19 @@ public:
 
     constexpr size_type length() const noexcept { return size(); }
 
-#if !defined __clang__ || HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type max_size() const noexcept {
-#if defined __clang__ // avoid constexpr issues with other, older compilers
-        (void) this; // loplugin:staticmethods
-#endif
+    constexpr size_type max_size() const noexcept {
+        (void) this; // silence loplugin:staticmethods
         return npos - 1;
     }
 
     constexpr bool empty() const noexcept { return size_ == 0; }
 
     constexpr const_reference operator [](size_type pos) const {
-#if HAVE_CXX14_CONSTEXPR
         assert(pos < size());
-#endif
         return data_[pos];
     }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    const_reference at(size_type pos) const {
+    constexpr const_reference at(size_type pos) const {
         if (pos >= size()) {
             throw std::out_of_range("o3tl::basic_string_view::at");
         }
@@ -247,42 +233,29 @@ public:
     }
 
     constexpr const_reference front() const {
-#if HAVE_CXX14_CONSTEXPR
         assert(!empty());
-#endif
         return operator [](0);
     }
 
     constexpr const_reference back() const {
-#if HAVE_CXX14_CONSTEXPR
         assert(!empty());
-#endif
         return operator [](size() - 1);
     }
 
     constexpr const_pointer data() const noexcept { return data_; }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    void remove_prefix(size_type n) {
+    constexpr void remove_prefix(size_type n) {
         assert(n <= size());
         data_ += n;
         size_ -= n;
     }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    void remove_suffix(size_type n) {
+    constexpr void remove_suffix(size_type n) {
         assert(n <= size());
         size_ -= n;
     }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    void swap(basic_string_view & s) noexcept {
+    constexpr void swap(basic_string_view & s) noexcept {
         std::swap(data_, s.data_);
         std::swap(size_, s.size_);
     }
@@ -296,10 +269,7 @@ public:
         return rlen;
     }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    basic_string_view substr(size_type pos = 0, size_type n = npos) const {
+    constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const {
         if (pos > size()) {
             throw std::out_of_range("o3tl::basic_string_view::copy");
         }
@@ -307,10 +277,7 @@ public:
             data() + pos, std::min(n, size_type(size() - pos)));
     }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    int compare(basic_string_view s) const noexcept {
+    constexpr int compare(basic_string_view s) const noexcept {
         auto n = traits::compare(data(), s.data(), std::min(size(), s.size()));
         return n == 0
             ? (size() < s.size() ? -1 : size() == s.size() ? 0 : 1) : n;
@@ -335,10 +302,7 @@ public:
         size_type pos1, size_type n1, charT const * s, size_type n2) const
     { return substr(pos1, n1).compare(basic_string_view(s, n2)); }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type find(basic_string_view s, size_type pos = 0) const noexcept {
+    constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept {
         if (s.size() <= size()) {
             for (auto xpos = pos; xpos <= size() - s.size(); ++xpos) {
                 bool match = true;
@@ -365,10 +329,7 @@ public:
     constexpr size_type find(charT const * s, size_type pos = 0) const
     { return find(basic_string_view(s), pos); }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type rfind(basic_string_view s, size_type pos = npos) const noexcept {
+    constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept {
         if (s.size() <= size()) {
             for (auto xpos = std::min<size_type>(size() - s.size(), pos);;
                  --xpos)
@@ -400,10 +361,7 @@ public:
     constexpr size_type rfind(charT const * s, size_type pos = npos) const
     { return rfind(basic_string_view(s), pos); }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type find_first_of(basic_string_view s, size_type pos = 0) const
+    constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const
         noexcept
     {
         for (auto xpos = pos; xpos < size(); ++xpos) {
@@ -426,10 +384,7 @@ public:
     constexpr size_type find_first_of(charT const * s, size_type pos = 0) const
     { return find_first_of(basic_string_view(s), pos); }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type find_last_of(basic_string_view s, size_type pos = npos) const
+    constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const
         noexcept
     {
         if (!empty()) {
@@ -459,10 +414,7 @@ public:
         const
     { return find_last_of(basic_string_view(s), pos); }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type find_first_not_of(basic_string_view s, size_type pos = 0) const
+    constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const
         noexcept
     {
         for (auto xpos = pos; xpos < size(); ++xpos) {
@@ -492,10 +444,7 @@ public:
         const
     { return find_first_not_of(basic_string_view(s), pos); }
 
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    size_type find_last_not_of(basic_string_view s, size_type pos = npos) const
+    constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const
         noexcept
     {
         if (!empty()) {
diff --git a/include/o3tl/strong_int.hxx b/include/o3tl/strong_int.hxx
index fb00addfad08..006a36c8900f 100644
--- a/include/o3tl/strong_int.hxx
+++ b/include/o3tl/strong_int.hxx
@@ -25,12 +25,10 @@
 #include <cassert>
 #include <type_traits>
 
-#include <config_global.h>
-
 namespace o3tl
 {
 
-#if HAVE_CXX14_CONSTEXPR
+#if !defined __COVERITY__
 
 namespace detail {
 
@@ -90,7 +88,7 @@ public:
         typename std::enable_if<std::is_integral<T>::value, int>::type = 0):
         m_value(value)
     {
-#if !defined __COVERITY__ && HAVE_CXX14_CONSTEXPR
+#if !defined __COVERITY__
         // catch attempts to pass in out-of-range values early
         assert(detail::isInRange<UNDERLYING_TYPE>(value)
                && "out of range");
diff --git a/include/o3tl/typed_flags_set.hxx b/include/o3tl/typed_flags_set.hxx
index 09f0b61d8c01..188258febc58 100644
--- a/include/o3tl/typed_flags_set.hxx
+++ b/include/o3tl/typed_flags_set.hxx
@@ -25,7 +25,6 @@
 #include <cassert>
 #include <type_traits>
 
-#include <config_global.h>
 #include <sal/types.h>
 
 namespace o3tl {
@@ -76,14 +75,12 @@ struct is_typed_flags {
         explicit constexpr Wrap(typename std::underlying_type<E>::type value):
             value_(value)
         {
-#if HAVE_CXX14_CONSTEXPR
             assert(detail::isNonNegative(value));
             assert(
                 static_cast<typename std::underlying_type<E>::type>(~0) == M
                     // avoid "operands don't affect result" warnings when M
                     // covers all bits of the underlying type
                 || (value & ~M) == 0);
-#endif
         }
 
         constexpr operator E() const { return static_cast<E>(value_); }
@@ -105,11 +102,9 @@ struct is_typed_flags {
 
 template<typename E>
 constexpr typename o3tl::typed_flags<E>::Wrap operator ~(E rhs) {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         o3tl::typed_flags<E>::mask
         & ~static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -126,14 +121,12 @@ template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator ~(
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator ^(
     E lhs, E rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(lhs)));
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         ^ static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -142,11 +135,9 @@ template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator ^(
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator ^(
     E lhs, typename o3tl::typed_flags<E>::Wrap rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(lhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         ^ static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -155,11 +146,9 @@ template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator ^(
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator ^(
     typename o3tl::typed_flags<E>::Wrap lhs, E rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         ^ static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -180,14 +169,12 @@ typename o3tl::typed_flags<typename W::Unwrapped::Self>::Wrap operator ^(
 
 template<typename E>
 constexpr typename o3tl::typed_flags<E>::Wrap operator &(E lhs, E rhs) {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(lhs)));
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         & static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -196,11 +183,9 @@ constexpr typename o3tl::typed_flags<E>::Wrap operator &(E lhs, E rhs) {
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator &(
     E lhs, typename o3tl::typed_flags<E>::Wrap rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(lhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         & static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -209,11 +194,9 @@ template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator &(
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator &(
     typename o3tl::typed_flags<E>::Wrap lhs, E rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         & static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -234,14 +217,12 @@ typename o3tl::typed_flags<typename W::Unwrapped::Self>::Wrap operator &(
 
 template<typename E>
 constexpr typename o3tl::typed_flags<E>::Wrap operator |(E lhs, E rhs) {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(lhs)));
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         | static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -250,11 +231,9 @@ constexpr typename o3tl::typed_flags<E>::Wrap operator |(E lhs, E rhs) {
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator |(
     E lhs, typename o3tl::typed_flags<E>::Wrap rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(lhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         | static_cast<typename std::underlying_type<E>::type>(rhs));
@@ -263,11 +242,9 @@ template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator |(
 template<typename E> constexpr typename o3tl::typed_flags<E>::Wrap operator |(
     typename o3tl::typed_flags<E>::Wrap lhs, E rhs)
 {
-#if HAVE_CXX14_CONSTEXPR
     assert(
         o3tl::detail::isNonNegative(
             static_cast<typename std::underlying_type<E>::type>(rhs)));
-#endif
     return static_cast<typename o3tl::typed_flags<E>::Wrap>(
         static_cast<typename std::underlying_type<E>::type>(lhs)
         | static_cast<typename std::underlying_type<E>::type>(rhs));
diff --git a/include/rtl/stringutils.hxx b/include/rtl/stringutils.hxx
index 6f3e18f9d202..ec8c88211593 100644
--- a/include/rtl/stringutils.hxx
+++ b/include/rtl/stringutils.hxx
@@ -16,10 +16,6 @@
 
 #include "sal/types.h"
 
-#if defined LIBO_INTERNAL_ONLY
-#include "config_global.h"
-#endif
-
 // The unittest uses slightly different code to help check that the proper
 // calls are made. The class is put into a different namespace to make
 // sure the compiler generates a different (if generating also non-inline)
@@ -157,7 +153,7 @@ struct ConstCharArrayDetector< const char[ N ], T >
     typedef T Type;
     static const std::size_t length = N - 1;
     static const bool ok = true;
-#if defined LIBO_INTERNAL_ONLY && HAVE_CXX14_CONSTEXPR
+#if defined LIBO_INTERNAL_ONLY
     constexpr
 #endif
     static bool isValid(char const (& literal)[N]) {
@@ -183,7 +179,7 @@ struct ConstCharArrayDetector< const char[ 1 ], T >
     typedef T Type;
     static const std::size_t length = 0;
     static const bool ok = true;
-#if defined LIBO_INTERNAL_ONLY && HAVE_CXX14_CONSTEXPR
+#if defined LIBO_INTERNAL_ONLY
     constexpr
 #endif
     static bool isValid(char const (& literal)[1]) {
@@ -202,10 +198,7 @@ struct ConstCharArrayDetector<char8_t const [N], T> {
     using Type = T;
     static constexpr bool const ok = true;
     static constexpr std::size_t const length = N - 1;
-#if HAVE_CXX14_CONSTEXPR
-    constexpr
-#endif
-    static bool isValid(char8_t const (& literal)[N]) {
+    static constexpr bool isValid(char8_t const (& literal)[N]) {
         for (std::size_t i = 0; i != N - 1; ++i) {
             if (literal[i] == u8'\0') {
                 return false;
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 7ab872e9d61d..d803a1ad4e6f 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -33,7 +33,6 @@
 #include "rtl/textenc.h"
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
-#include "config_global.h"
 #include "rtl/stringconcat.hxx"
 #endif
 
@@ -79,10 +78,8 @@ struct SAL_WARN_UNUSED OUStringLiteral
         data(
             libreoffice_internal::ConstCharArrayDetector<T>::toPointer(literal))
     {
-#if HAVE_CXX14_CONSTEXPR
         assert(
             libreoffice_internal::ConstCharArrayDetector<T>::isValid(literal));
-#endif
     }
 
     int size;
diff --git a/include/svl/itemset.hxx b/include/svl/itemset.hxx
index 23d994ddb968..ba21e61ff1f8 100644
--- a/include/svl/itemset.hxx
+++ b/include/svl/itemset.hxx
@@ -27,7 +27,6 @@
 #include <type_traits>
 #include <memory>
 
-#include <config_global.h>
 #include <svl/svldllapi.h>
 #include <svl/poolitem.hxx>
 #include <svl/typedwhich.hxx>
@@ -57,9 +56,7 @@ constexpr bool validRanges() {
 // std::size_t is no smaller than sal_uInt16:
 
 constexpr std::size_t rangeSize(sal_uInt16 wid1, sal_uInt16 wid2) {
-#if HAVE_CXX14_CONSTEXPR
     assert(validRange(wid1, wid2));
-#endif
     return wid2 - wid1 + 1;
 }