Add SCN_CONSTEXPRIF

eliaskosunen · Nov 2, 2023 · 7e8007a · 7e8007a
1 parent f27930c
commit 7e8007a
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/include/scn/detail/config.h b/include/scn/detail/config.h
@@ -282,6 +282,15 @@
 #define SCN_CONSTEXPR14 inline
 #endif
 
+
+// Detect if constexpr
+#if (defined(__cpp_if_constexpr) && __cpp_if_constexpr >= 201606) || \
+    ((SCN_MSVC >= SCN_COMPILER(19, 11, 0) && SCN_MSVC_LANG >= SCN_STD_17))
+#define SCN_CONSTEXPRIF constexpr
+#else
+#define SCN_CONSTEXPRIF
+#endif
+
 // Detect string_view
 #if defined(__cpp_lib_string_view) && __cpp_lib_string_view >= 201603 && \
     SCN_STD >= SCN_STD_17

diff --git a/src/locale.cpp b/src/locale.cpp
@@ -256,7 +256,7 @@ namespace scn {
             span<const char_type> ch) const
         {
             const auto& locale = to_locale(*this);
-            if (sizeof(CharT) == 1) {
+            if SCN_CONSTEXPRIF (sizeof(CharT) == 1) {
                 SCN_EXPECT(ch.size() >= 1);
                 code_point cp{};
                 auto it = parse_code_point(ch.begin(), ch.end(), cp);
@@ -271,7 +271,7 @@ namespace scn {
             span<const char_type> ch) const
         {
             const auto& locale = to_locale(*this);
-            if (sizeof(CharT) == 1) {
+            if SCN_CONSTEXPRIF (sizeof(CharT) == 1) {
                 SCN_EXPECT(ch.size() >= 1);
                 code_point cp{};
                 auto it = parse_code_point(ch.begin(), ch.end(), cp);
@@ -298,7 +298,7 @@ namespace scn {
         const                                                             \
     {                                                                     \
         const auto& locale = to_locale(*this);                            \
-        if (sizeof(CharT) == 1) {                                         \
+        if SCN_CONSTEXPRIF (sizeof(CharT) == 1) {                                         \
             SCN_EXPECT(ch.size() >= 1);                                   \
             code_point cp{};                                              \
             auto it = parse_code_point(ch.begin(), ch.end(), cp);         \
@@ -348,7 +348,7 @@ namespace scn {
             span<const char_type> ch) const
         {
             const auto& locale = to_locale(*this);
-            if (sizeof(CharT) == 1) {
+            if SCN_CONSTEXPRIF (sizeof(CharT) == 1) {
                 SCN_EXPECT(ch.size() >= 1);
                 code_point cp{};
                 auto it = parse_code_point(ch.begin(), ch.end(), cp);