cppfront compilation failing with msvc 2022

[vanceism7]

Hello!

Love this project, I've been following it for a little while now and decided I wanted to start playing around with it for myself and/or maybe try to contribute if I can.

I tried following the instructions given on the documentation site to compile cppfront, namely:

Cppfront builds with any recent C++ compiler. Go to the /cppfront/source directory, and run one of the following:
cl cppfront.cpp -std:c++20 -EHsc

I'm (unfortunately) running windows, so I'm trying it out using the msvc compiler. When trying to build this, the compiler hits 100+ error and quits out. I installed visual studio build tools 2022 and am trying to compile within vscode. (if its relevant, vscode has to be opened via "msvc developer powershell", otherwise the environment can't see cl.exe).

Note: I also tried this with mingw's g++ and the compiler didn't error out, but I left it running in the background and after about 8 hours decided something must be wrong.
Edit: This probably doesn't matter. My MSys2 install was pretty old so this probably isn't a useful diagnostic

I'm opening this as a discussion rather than an issue because I assume the problem is probably me, but I can move this to an issue if there actually is something wrong.

Here's the compiler log:

fs\cppfront\source\../include/cpp2util.h(2487): error C7595: 'std::source_location::current': call to immediate function is not a constant expression
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\source_location(29): note: failure was caused by attempting to access a member on an object of dynamic type 'std::source_location' in which the member is not defined
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\source_location(29): note: see usage of 'std::source_location::source_location'
reflect.h2(165): note: see reference to function template instantiation 'decltype(auto) cpp2::impl::as_<std::string,const std::string_view&>(_T0)' being compiled
        with
        [
            _T0=const std::string_view &
        ]
fs\cppfront\source\../include/cpp2util.h(3376): error C2059: syntax error: ')'
fs\cppfront\source\../include/cpp2util.h(3376): error C2143: syntax error: missing ';' before '{'
fs\cppfront\source\../include/cpp2util.h(3378): error C2338: No safe 'as' cast available - please check your cast
fs\cppfront\source\../include/cpp2util.h(3383): error C2059: syntax error: 'return'
fs\cppfront\source\../include/cpp2util.h(3383): error C2065: 'C': undeclared identifier
fs\cppfront\source\../include/cpp2util.h(3383): error C2065: 'x': undeclared identifier
fs\cppfront\source\../include/cpp2util.h(3384): error C2059: syntax error: '}'
fs\cppfront\source\../include/cpp2util.h(3384): error C2143: syntax error: missing ';' before '}'
reflect.h2(418): error C2059: syntax error: ')'
reflect.h2(418): error C2143: syntax error: missing ';' before '{'
reflect.h2(418): error C2447: '{': missing function header (old-style formal list?)
reflect.h2(422): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
reflect.h2(422): error C2065: 'n': undeclared identifier
reflect.h2(422): error C2065: 'stmt': undeclared identifier
reflect.h2(422): error C2672: 'std::move': no matching overloaded function found
reflect.h2(422): error C2780: '_FwdIt2 std::move(_ExPo &&,_FwdIt1,_FwdIt1,_FwdIt2) noexcept': expects 4 arguments - 1 provided
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\xutility(4280): note: see declaration of 'std::move'    
reflect.h2(422): error C2780: '_OutIt std::move(_InIt,_InIt,_OutIt)': expects 3 arguments - 1 provided
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\xutility(4268): note: see declaration of 'std::move'    
reflect.h2(422): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(422): error C2440: 'initializing': cannot convert from 'std::string' to 'int'
reflect.h2(422): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
reflect.h2(424): error C2059: syntax error: '}'
reflect.h2(424): error C2143: syntax error: missing ';' before '}'
reflect.h2(426): error C2653: 'function_declaration': is not a class or namespace name
reflect.h2(427): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
reflect.h2(427): error C2061: syntax error: identifier 'declaration'
reflect.h2(427): error C2143: syntax error: missing ';' before '}'
reflect.h2(427): error C2059: syntax error: '}'
reflect.h2(435): error C2653: 'object_declaration': is not a class or namespace name
reflect.h2(438): error C2065: 'compiler_services': undeclared identifier
reflect.h2(438): error C2923: 'cpp2::impl::in': 'compiler_services' is not a valid template type argument for parameter 'T'
reflect.h2(438): note: see declaration of 'compiler_services'
reflect.h2(440): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
reflect.h2(440): error C2374: 'cpp2::impl::declaration': redefinition; multiple initialization
reflect.h2(427): note: see declaration of 'cpp2::impl::declaration'
reflect.h2(440): error C2065: 'n_': undeclared identifier
reflect.h2(440): error C2065: 's': undeclared identifier
reflect.h2(440): error C2059: syntax error: '{'
reflect.h2(440): error C2143: syntax error: missing ';' before '{'
reflect.h2(440): error C2447: '{': missing function header (old-style formal list?)
reflect.h2(445): error C2653: 'object_declaration': is not a class or namespace name
reflect.h2(445): error C2270: 'is_const': modifiers not allowed on nonmember functions
reflect.h2(445): error C2065: 'n': undeclared identifier
reflect.h2(445): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(446): error C2653: 'object_declaration': is not a class or namespace name
reflect.h2(446): error C2270: 'has_wildcard_type': modifiers not allowed on nonmember functions
reflect.h2(446): error C2065: 'n': undeclared identifier
reflect.h2(446): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(448): error C2653: 'object_declaration': is not a class or namespace name
reflect.h2(448): error C2270: 'type': modifiers not allowed on nonmember functions
reflect.h2(449): error C2065: 'n': undeclared identifier
reflect.h2(449): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(449): error C2119: 'ret': the type for 'auto' cannot be deduced from an empty initializer
reflect.h2(450): error C2064: term does not evaluate to a function taking 2 arguments
reflect.h2(452): error C2440: 'return': cannot convert from 'int' to 'std::basic_string<char,std::char_traits<char>,std::allocator<char>>'        
reflect.h2(452): note: No constructor could take the source type, or constructor overload resolution was ambiguous
reflect.h2(455): error C2653: 'object_declaration': is not a class or namespace name
reflect.h2(455): error C2270: 'initializer': modifiers not allowed on nonmember functions
reflect.h2(456): error C2065: 'n': undeclared identifier
reflect.h2(456): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(456): error C2119: 'ret': the type for 'auto' cannot be deduced from an empty initializer
reflect.h2(457): error C2064: term does not evaluate to a function taking 2 arguments
reflect.h2(459): error C2440: 'return': cannot convert from 'int' to 'std::basic_string<char,std::char_traits<char>,std::allocator<char>>'        
reflect.h2(459): note: No constructor could take the source type, or constructor overload resolution was ambiguous
reflect.h2(462): error C2653: 'object_declaration': is not a class or namespace name
reflect.h2(462): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
reflect.h2(462): error C2059: syntax error: 'const'
reflect.h2(463): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
reflect.h2(463): error C2374: 'cpp2::impl::declaration': redefinition; multiple initialization
reflect.h2(427): note: see declaration of 'cpp2::impl::declaration'
reflect.h2(463): error C2061: syntax error: identifier 'declaration'
reflect.h2(463): error C2143: syntax error: missing ';' before '}'
reflect.h2(463): error C2059: syntax error: '}'
reflect.h2(471): error C2653: 'type_declaration': is not a class or namespace name
reflect.h2(474): error C2065: 'compiler_services': undeclared identifier
reflect.h2(474): error C2923: 'cpp2::impl::in': 'compiler_services' is not a valid template type argument for parameter 'T'
reflect.h2(474): note: see declaration of 'compiler_services'
reflect.h2(476): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
reflect.h2(476): error C2374: 'cpp2::impl::declaration': redefinition; multiple initialization
reflect.h2(427): note: see declaration of 'cpp2::impl::declaration'
reflect.h2(476): error C2065: 'n_': undeclared identifier
reflect.h2(476): error C2065: 's': undeclared identifier
reflect.h2(476): error C2059: syntax error: '{'
reflect.h2(476): error C2143: syntax error: missing ';' before '{'
reflect.h2(476): error C2447: '{': missing function header (old-style formal list?)
reflect.h2(481): error C2653: 'type_declaration': is not a class or namespace name
reflect.h2(482): error C2270: 'reserve_names': modifiers not allowed on nonmember functions
reflect.h2(484): error C3861: 'get_members': identifier not found
reflect.h2(484): note: 'get_members': function declaration must be available as none of the arguments depend on a template parameter
reflect.h2(486): error C3861: 'get_metafunction_name': identifier not found
reflect.h2(487): error C3861: 'get_metafunction_name': identifier not found
reflect.h2(487): note: 'get_metafunction_name': function declaration must be available as none of the arguments depend on a template parameter    
reflect.h2(495): error C2653: 'type_declaration': is not a class or namespace name
reflect.h2(495): error C2270: 'is_polymorphic': modifiers not allowed on nonmember functions
reflect.h2(495): error C2065: 'n': undeclared identifier
reflect.h2(495): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(496): error C2653: 'type_declaration': is not a class or namespace name
reflect.h2(496): error C2270: 'is_final': modifiers not allowed on nonmember functions
reflect.h2(496): error C2065: 'n': undeclared identifier
reflect.h2(496): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(497): error C2653: 'type_declaration': is not a class or namespace name
reflect.h2(497): error C2270: 'make_final': modifiers not allowed on nonmember functions
reflect.h2(497): error C2065: 'n': undeclared identifier
reflect.h2(497): error C2672: 'operator __surrogate_func': no matching overloaded function found
reflect.h2(499): error C2653: 'type_declaration': is not a class or namespace name
reflect.h2(499): error C2065: 'function_declaration': undeclared identifier
reflect.h2(499): error C2923: 'std::vector': 'function_declaration' is not a valid template type argument for parameter '_Ty'
reflect.h2(499): note: see declaration of 'function_declaration'
reflect.h2(499): error C2976: 'std::vector': too few template arguments
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\vector(432): note: see declaration of 'std::vector'     
reflect.h2(499): error C2955: 'std::vector': use of class template requires template argument list
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\vector(432): note: see declaration of 'std::vector'     
reflect.h2(501): error C2270: 'get_member_functions': modifiers not allowed on nonmember functions
reflect.h2(501): error C2955: 'std::vector': use of class template requires template argument list
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\vector(432): note: see declaration of 'std::vector'     
reflect.h2(501): error C2079: 'cpp2::impl::get_member_functions' uses undefined class 'std::vector'
reflect.h2(502): error C2065: 'function_declaration': undeclared identifier
reflect.h2(502): error C2923: 'std::vector': 'function_declaration' is not a valid template type argument for parameter '_Ty'
reflect.h2(502): note: see declaration of 'function_declaration'
reflect.h2(502): error C2976: 'std::vector': too few template arguments
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\vector(432): note: see declaration of 'std::vector'     
reflect.h2(502): error C2641: cannot deduce template arguments for 'std::vector'
reflect.h2(502): error C2783: 'std::vector<_Ty,_Alloc> std::vector(void) noexcept(<expr>)': could not deduce template argument for '_Ty'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\vector(464): note: see declaration of 'std::vector'     
reflect.h2(502): fatal error C1003: error count exceeds 100; stopping compilation

[zaucy]

I'm using

cl /nologo /std:c++latest /EHsc cppfront.cpp

(this is where I'm using it)

'latest' instead of c++20 but I'm also using msvc 14.41. If you are able maybe try updating visual studio.

[vanceism7]

I think what you said here is basically the answer:

Make sure you have a sufficiently new cl version. As of writing, it should be v19.

Edit:

Also, make sure that your up-to-date compiler is also using the up-to-date libs! In one case, I've gotten compiler errors the same as the original question even though my compiler was v19 because it was using v14 libs. See the log:

Microsoft (R) C/C++ Optimizing Compiler Version 19.31.31104 for x86
Copyright (C) Microsoft Corporation. All rights reserved.

cppfront.cpp
The contents of are available only in c++latest mode with concepts support;
see microsoft/STL#1814 for details.
The contents of are available only in c++latest mode with concepts support;
see microsoft/STL#1814 for details.
D:\code\bin\cppfront\source../include/cpp2util.h(2273): error C2039: 'vformat': is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\variant(30): note: see declaration of 'std'

Thanks again!

[vanceism7]

I actually did try this with originally with std:c++latest because it had been failing for missing features with c++20, and thats what gave me the list of compiler errors above. Currently I'm using cl version 19.41.34120 - I don't think there's a newer version than this.

But weird, I just tried this again using the original command recommended in the guide (cl cppfront.cpp -std:c++20 -EHsc) and now its working. I have no idea why or what changed. Maybe my compiler was in an inconsistent state and I needed to restart my computer. I dno, but I guess I'm good. Thanks for checking in with me on this!

Note:
This was also failing for me with MinGW g++ in windows. I was running into the issue of having too many sections and (atleast for me, but maybe someone else can verify), the correct command should be g++ cppfront.cpp -std=c++20 -o cppfront -Wa,-mbig-obj, specifically, the last arg should be -Wa,-mbig-obj instead of /Wa,-mbig-obj. Im using the w64devkit shell, maybe its a more faithful representation of unix and wants the unix version of the cli arg with the - instead of the windows /.

It's still failing to compile with Clang though.
See #1294 where someone else ran into the same issue. My compiler results with clang have been the same as theirs

[zaucy]

If it helps your original log you posted showed an older version was being used. Indicated by the paths shown

[vanceism7]

Ah yea you're right. So I suppose that must've been the main issue as far as cl.exe goes. I don't know why it was on such an old version because I was using vs 2022 developer shell the entire time. But yea, guess that's it. Thanks!