[driver] [cl] Add/fix c++17/c++latest

[daxpedda]

Summary

Current "/std:c++latest" adds "-std=c++17", VS has its own "/std:c++17" for that now.

This is my first commit by the way, please tell me if there is anything I can do to improve.
Thanks.

[daxpedda]

Discovered that these flags were tested and added new test.

[martell]

LGTM

we should probably set c++17 as the default over c++14 as part of this change.
given that everything seems in order for c++17 bar P0522R0 so this looks like the change should be good.
adding @rnk to confirm.

@daxpedda do you have commit access?

test/Driver/cl-options.c

514 ↗

(On Diff #116154)

We should probably change the default to c++17 as part of this commit.

[daxpedda]

According to this the default is still c++14.
I do not have commit access, I would prefer if somebody else commits this in my stead.

test/Driver/cl-options.c

514 ↗

(On Diff #116154)

According to this the default is still c++14.

[martell]

It seems that msvc enabled some c++17 features when in c++14 mode and they left them enabled because projects became dependant on them.
switching to c++17 as the default and removing the c++17 features from c++14 mode seems like the correct thing to do here even if MS still use c++14 as their default.
That should be part of a different patch though because a discussion needs to be had on that issue.

LGTM as is.
Thanks for the contribution.

[rnk]

Sorry for the delay, thank you, this looks good! @martell, do you mind landing this?

[martell]

Landed, @rnk I missed this message in my travels from Ireland back to Mountain View.
Just catching up with everything now :)

[martell]

cfe/trunk/test/Driver/cl-options.c

524

This was incorrect, it should have been STDCXX17.
I fixed this is rL315868

cfe/trunk/lib/Driver/ToolChains/Clang.cpp

CmdArgs.push_back(
         Args.MakeArgString("-fms-compatibility-version=" + MSVT.getAsString()));
 
   bool IsMSVC2015Compatible = MSVT.getMajor() >= 19;
   if (ImplyVCPPCXXVer) {
     StringRef LanguageStandard;
     if (const Arg *StdArg = Args.getLastArg(options::OPT__SLASH_std)) {
       LanguageStandard = llvm::StringSwitch<StringRef>(StdArg->getValue())
                              .Case("c++14", "-std=c++14")
-                             .Case("c++latest", "-std=c++1z")
+                             .Case("c++17", "-std=c++17")
+                             .Case("c++latest", "-std=c++2a")
                              .Default("");
       if (LanguageStandard.empty())
         D.Diag(clang::diag::warn_drv_unused_argument)
             << StdArg->getAsString(Args);
     }
 
     if (LanguageStandard.empty()) {
       if (IsMSVC2015Compatible)

cfe/trunk/test/Driver/cl-options.c

 // CXX11: -std=c++11
 
 // RUN: %clang_cl -fmsc-version=1900 -TP -### -- %s 2>&1 | FileCheck -check-prefix=CXX14 %s
 // CXX14: -std=c++14
 
 // RUN: %clang_cl -fmsc-version=1900 -TP -std:c++14 -### -- %s 2>&1 | FileCheck -check-prefix=STDCXX14 %s
 // STDCXX14: -std=c++14
 
+// RUN: %clang_cl -fmsc-version=1900 -TP -std:c++17 -### -- %s 2>&1 | FileCheck -check-prefix=STDCXX17 %s
+// STDCXX14: -std=c++17
+
 // RUN: %clang_cl -fmsc-version=1900 -TP -std:c++latest -### -- %s 2>&1 | FileCheck -check-prefix=STDCXXLATEST %s
-// STDCXXLATEST: -std=c++1z
+// STDCXXLATEST: -std=c++2a
 
 // RUN: env CL="/Gy" %clang_cl -### -- %s 2>&1 | FileCheck -check-prefix=ENV-CL %s
 // ENV-CL: "-ffunction-sections"
 
 // RUN: env CL="/Gy" _CL_="/Gy- -- %s" %clang_cl -### 2>&1 | FileCheck -check-prefix=ENV-_CL_ %s
 // ENV-_CL_-NOT: "-ffunction-sections"
 
 // RUN: env CL="%s" _CL_="%s" not %clang --rsp-quoting=windows -c