Compile-time error when using a raw string literal inside of REQUIRE (MSVC 2017)

[agurtovoy]

Description

The following test fails to compile on MSVC2017 (with /std:c++17 and /permissive- flags on):

#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include <doctest/doctest.h>

#include <string>

std::string foo( std::string const& ) { return ""; }

TEST_CASE( "[raw string literals]" ) 
{
    auto str = foo(R"(cl "-DNAME=\"Bob\"" test.cpp)"); // OK
    REQUIRE( foo(R"(cl "-DNAME=\"Bob\"" test.cpp)") == "" ); // Fails to compile
}

../main.cpp(11): error C2017: illegal escape sequence
../main.cpp(11): error C3688: invalid literal suffix 'Bob'; literal operator or literal operator template 'operator ""Bob' not found
../main.cpp(11): error C2661: 'doctest::detail::ResultBuilder::ResultBuilder': no overloaded function takes 3 arguments
n

Preprocessing the source file shows that the offending line expands to:

 do {  doctest::detail::ResultBuilder _DOCTEST_RB(doctest::assertType::DT_REQUIRE, "main2.cpp", 11, "foo(R\"(cl \"-DNAME=\\"Bob\\\"\" test.cpp)\") == \"\""); try { _DOCTEST_RB.setResult( doctest::detail::ExpressionDecomposer(doctest::assertType::DT_REQUIRE) << foo(R"(cl "-DNAME=\"Bob\"" test.cpp)") == ""); } catch(...) { _DOCTEST_RB.translateException(); } if(_DOCTEST_RB.log()) __debugbreak(); _DOCTEST_RB.react() ; } while((void)0, 0);

Escaping in the "foo(R\"(cl \"-DNAME=\\"Bob\\\"\" test.cpp)\") == \"\"" literal is problematic.

Steps to reproduce

All cl command flags (excluding -I paths):

"/MD" "/nologo" "/showIncludes" "/W3" "/EHsc" "/std:c++17" "/permissive-" "/Ob2" "/Gw" "/O2" "-D_CRT_SECURE_NO_WARNINGS" "-DNOMINMAX" "-O2" "-Ob2" "-MD" "-DNDEBUG"

Extra information

• doctest version: v2.3.1
• Operating System: Windows 10
• Compiler+version: Microsoft (R) C/C++ Optimizing Compiler Version 19.11.25547 for x64

[onqtam]

Strange that there's no problem with GCC/Clang... For now you can workaround it by using a local variable - I'll look at this at some point in the future... Thanks for reporting!

[agurtovoy]

@onqtam Yep, that's what I did, just thought I'd report it. Could be a compiler bug, haven't tried it in VS2019 with /experimental:preprocessor on.

[onqtam]

I can confirm that using /experimental:preprocessor fixes the problem, so I'll close this since it's an MSVC issue and there's nothing I can do anyway.