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On 2020-02-26, Reid Kleckner via llvm-dev wrote:
\>I think "legacy" is the answer to most of your questions.
\>
\>1\. I think clang still uses ld by default, so clang-cl is similar. Besides,
\>every build system we encountered migrating from MSVC calls \`link\`
\>directly, and needed to be updated to call \`lld-link\`.
\>
\>2\. I think we should probably configure lld to find the clang resource
\>directory. At the very least, clang-cl -fuse-ld=lld should add it.
\>
\>3\. I think this is because there is no clang spelling for the /MD & /MT
\>flags, so we have to pick some CRT so that hello world links. You can work
\>around it with -nodefaultlib and passing your own.
\>
\>4\. That's true, but that's been the case for every build system we've
\>encountered.
\>
\>So, I think there is room for improvement and better defaults.
\>
\>Most options in clang are controlled by flags, not configure-time cmake
\>options. From the clang developer perspective, this is good, clang is
\>always a cross compiler and can do anything anywhere at runtime. But from a
\>user or packager perspective, this is often painful. Users often write
\>compiler wrapper scripts to fill in their preferred default options:
\>default target, default include paths, default library paths, etc.
\>
\>On Sun, Feb 23, 2020 at 12:37 PM Максим Власов via llvm-dev <
\>llvm-dev@lists.llvm.org> wrote:
\>
\>> I'm getting trouble using clang with compiled libc++ on MSVC.
\>> 1\. why clang chooses \`link\` over \`lld-link\` by default? I don't really
\>> wish to write \`-fuse-ld=lld-link\` every single time I build something.
\>> 2\. why \`lld-link\` doesn't search inside default \`lib\` directory? I need to
\>> manually show him where it is although I put that binary in \` \>> root>\\lib\\\`
\>> 3\. why clang invokes linker with \`-defaultlib:libcmt\`? I mean libc++ build
\>> guide under MSVC produces -MD version of either \`libc++.lib\` or \`c++.lib\`
\>> 4\. Since (3), it's not possible to build anything without splitting
\>> compiler and linker calls - \`clang\` by default produces -MT versions of
\>> objects and linker fails to compose it with -MD library. No, \`-dynamic\`
\>> flag does not help either.
\>> Any fixes to these? Can I config clang somehow except \`--config\` option?

May I rephrase the question as asking about the feasibility of GCC
\-specs= ?

https://gcc.gnu.org/onlinedocs/gcc/Spec-Files.html
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