make string_view(const char*) constructor constexpr only in C++17 and…

… later (#4774)
bloomberg · Jun 3, 2024 · e7da859 · e7da859
1 parent 1f74743
commit e7da859
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Showing 2 changed files with 27 additions and 10 deletions.
diff --git a/groups/bsl/bslstl/bslstl_stringview.h b/groups/bsl/bslstl/bslstl_stringview.h
@@ -227,6 +227,12 @@ BSLS_IDENT("$Id: $")
 #define BSLSTL_STRING_VIEW_AND_STD_STRING_VIEW_COEXIST
 #endif
 
+#if defined(BSLS_LIBRARYFEATURES_HAS_CPP17_BASELINE_LIBRARY)
+#define BSLSTL_STRING_VIEW_CHAR_TRAITS_LENGTH_CONSTEXPR constexpr
+#else
+#define BSLSTL_STRING_VIEW_CHAR_TRAITS_LENGTH_CONSTEXPR
+#endif
+
 // 'BDE_DISABLE_CPP17_ABI' is intended for CI builds only, to allow simulation
 // of Sun/AIX builds on Linux hosts.  It is an error to define this symbol in
 // Bloomberg production builds.
@@ -446,7 +452,7 @@ class basic_string_view {
         // Create a view that has the same value as the specified 'original'
         // object.
 
-    BSLS_KEYWORD_CONSTEXPR_CPP14
+    BSLSTL_STRING_VIEW_CHAR_TRAITS_LENGTH_CONSTEXPR
     basic_string_view(const CHAR_TYPE *characterString);  // IMPLICIT
         // Create a view of the specified null-terminated 'characterString' (of
         // length 'CHAR_TRAITS::length(characterString)').
@@ -1424,7 +1430,7 @@ basic_string_view<CHAR_TYPE,CHAR_TRAITS>::basic_string_view()
 
 template <class CHAR_TYPE, class CHAR_TRAITS>
 BSLS_PLATFORM_AGGRESSIVE_INLINE
-BSLS_KEYWORD_CONSTEXPR_CPP14
+BSLSTL_STRING_VIEW_CHAR_TRAITS_LENGTH_CONSTEXPR
 basic_string_view<CHAR_TYPE, CHAR_TRAITS>::basic_string_view(
                                               const CHAR_TYPE *characterString)
 : d_start_p(characterString)
@@ -2772,6 +2778,7 @@ void bslh::hashAppend(
 }  // close enterprise namespace
 #endif  // BSLSTL_STRING_VIEW_IS_ALIASED
 
+#undef BSLSTL_STRING_VIEW_CHAR_TRAITS_LENGTH_CONSTEXPR
 #undef BSLSTL_STRING_VIEW_AND_STD_STRING_VIEW_COEXIST
 
 #endif

diff --git a/groups/bsl/bslstl/bslstl_stringview.t.cpp b/groups/bsl/bslstl/bslstl_stringview.t.cpp
@@ -1,6 +1,8 @@
 // bslstl_stringview.t.cpp                                            -*-C++-*-
 #include <bslstl_stringview.h>
 
+#include <bsla_maybeunused.h>
+
 #include <bslstl_algorithm.h>  // bsl::count()
 
 #include <bslma_default.h>
@@ -1131,7 +1133,8 @@ void TestDriver<TYPE,TRAITS>::testCase25()
 # ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_BASELINE_LIBRARY
     // check constexpr construction
     constexpr std::string_view dummy1("0123456789");
-    constexpr bsl::string_view dummy2(dummy1);
+
+    BSLA_MAYBE_UNUSED constexpr bsl::string_view dummy2(dummy1);
 # endif
 #endif
 
@@ -5692,6 +5695,11 @@ void TestDriver<TYPE, TRAITS>::testCase8()
     }
 #endif
 
+#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_BASELINE_LIBRARY
+    // check constexpr construction
+    BSLA_MAYBE_UNUSED constexpr bsl::string_view dummy("0123456789");
+#endif
+
     // Verify no memory was ever allocated.
     ASSERTV(da.numBlocksTotal(), 0 == da.numBlocksTotal());
 }
@@ -6250,10 +6258,11 @@ void TestDriver<TYPE, TRAITS>::testCase5()
     // Check that no additional memory has been allocated.
     ASSERTV(da.numBytesTotal(), 0 == da.numBytesTotal());
 
-#ifdef BSLS_COMPILERFEATURES_SUPPORT_CONSTEXPR_CPP14
     // check constexpr construction
-    constexpr bsl::string_view dummy1("0123456789");
-    constexpr bsl::string_view dummy2(dummy1);
+#ifdef BSLS_COMPILERFEATURES_SUPPORT_CONSTEXPR_CPP14
+    constexpr bsl::string_view dummy1("0123456789", 10);
+
+    BSLA_MAYBE_UNUSED constexpr bsl::string_view dummy2(dummy1);
 #endif
 }
 
@@ -6630,7 +6639,7 @@ void TestDriver<TYPE, TRAITS>::testCase2()
             fa.deleteObject(objPtr);
         }
 #ifdef BSLS_COMPILERFEATURES_SUPPORT_CONSTEXPR
-        constexpr Obj dummy;
+        BSLA_MAYBE_UNUSED constexpr Obj dummy;
 #endif
     }
 
@@ -6681,9 +6690,10 @@ void TestDriver<TYPE, TRAITS>::testCase2()
         }
 #ifdef BSLS_COMPILERFEATURES_SUPPORT_CONSTEXPR_CPP14
         // check constexpr construction
-        constexpr bsl::string_view dummy1("0123456789");
-        constexpr bsl::string_view dummy2("0123456789", 9);
-        constexpr bsl::string_view dummy3(dummy2.begin(), dummy2.end());
+        constexpr bsl::string_view dummy1("0123456789", 9);
+
+        BSLA_MAYBE_UNUSED constexpr bsl::string_view dummy2(dummy1.begin(),
+                                                            dummy1.end());
 #endif
     }