LLVM Project News and Details from the Trenches
Monday, November 18, 2013
Tuesday, November 5, 2013
There has been a lot of work lately towards bringing an LLVM toolchain to the Windows platform (see A path forward for an LLVM toolchain on Windows). One result of that work is a new driver mode for Clang: clang-cl. This mode makes Clang understand the same kind of command-line arguments as Visual Studio's compiler, cl.exe. For example, a typical command to compile a file into an executable with Clang might be "clang hello.cc -o hello", whereas with cl.exe, one would use "cl.exe hello.cc /Fehello". Now one can use the latter syntax with Clang by substituting "cl.exe" with "clang-cl". This makes it easy to use Clang for existing projects in Visual Studio.
For the most part, clang-cl accepts exactly the same arguments as cl.exe. However, it also accepts some Clang-specific options. One such option that was added recently is the /fallback flag. The purpose of this flag is to make it easy to use clang-cl even in projects where Clang cannot yet compile all of the code. This post gives an example of how /fallback can be used.