From 4113a12c69809d72a3d92345ec47ccc5a0bf141c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <martin.horenovsky@gmail.com>
Date: Thu, 19 Aug 2021 19:06:23 +0200
Subject: [PATCH] Fix Wreserved-identifier for UDLs in Catch2

See #578
---
 docs/contributing.md                    | 17 +++++++++++++++++
 src/catch2/catch_approx.hpp             |  4 ++--
 src/catch2/internal/catch_stringref.hpp |  4 ++--
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/docs/contributing.md b/docs/contributing.md
index dc6bb537..f70b1e45 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -239,6 +239,23 @@ there is no difference is wrong, QNX and VxWorks won't compile if you
 include the header as `<cfoo>` and call the function unqualified.
 
 
+#### User-Defined Literals (UDL) for Catch2' types
+
+Due to messy standardese and ... not great ... implementation of
+`-Wreserved-identifier` in Clang, avoid declaring UDLs as
+```cpp
+Approx operator "" _a(long double);
+```
+and instead declare them as
+```cpp
+Approx operator ""_a(long double);
+```
+
+Notice that the second version does not have a space between the `""` and
+the literal suffix.
+
+
+
 ### New source file template
 
 If you are adding new source file, there is a template you should use.
diff --git a/src/catch2/catch_approx.hpp b/src/catch2/catch_approx.hpp
index 74833494..8f0e6327 100644
--- a/src/catch2/catch_approx.hpp
+++ b/src/catch2/catch_approx.hpp
@@ -114,8 +114,8 @@ namespace Catch {
     };
 
 namespace literals {
-    Approx operator "" _a(long double val);
-    Approx operator "" _a(unsigned long long val);
+    Approx operator ""_a(long double val);
+    Approx operator ""_a(unsigned long long val);
 } // end namespace literals
 
 template<>
diff --git a/src/catch2/internal/catch_stringref.hpp b/src/catch2/internal/catch_stringref.hpp
index fed35b16..17f5d07d 100644
--- a/src/catch2/internal/catch_stringref.hpp
+++ b/src/catch2/internal/catch_stringref.hpp
@@ -98,12 +98,12 @@ namespace Catch {
     };
 
 
-    constexpr auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
+    constexpr auto operator ""_sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
         return StringRef( rawChars, size );
     }
 } // namespace Catch
 
-constexpr auto operator "" _catch_sr( char const* rawChars, std::size_t size ) noexcept -> Catch::StringRef {
+constexpr auto operator ""_catch_sr( char const* rawChars, std::size_t size ) noexcept -> Catch::StringRef {
     return Catch::StringRef( rawChars, size );
 }