Saturday, April 16, 2016

“Clang: error: no input files” in OS X

By Hường Hana 5:30 PM , , Leave a Comment

Following this solution, I use #include "...frontend/tokens.mll" in my lexer.mll, then I use cpp -P frontend/lexer.mll -o frontend/gen/lexer.mll to generate the complete mll file. This solution worked before under Ubuntu.

Now, I try to do this in Mac OS 10.11.1, it gives an error clang: error: no input files.

gcc -v returns

Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 7.3.0 (clang-703.0.29) Target: x86_64-apple-darwin15.0.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin

I don't see where I use XCode, or PCH file. Does anyone know how I should configure the environment to make cpp work?

Edit 1:

cpp --version returns

Apple LLVM version 7.3.0 (clang-703.0.29) Target: x86_64-apple-darwin15.0.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin

And an example from the comment:

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4 Answers

Answers 1

It could be a bug from clang, as this one works for me:

$ cpp -P xxx yyy $ cat yyy from zzz

and

$ clang --version Apple LLVM version 7.0.2 (clang-700.1.81) Target: x86_64-apple-darwin14.5.0 Thread model: posix

Answers 2

So if I understand correctly what you are trying to do, you want to run the c preprocessor on a file to produce text output which will be stored in another file. I don't know why but, here is a command that will accomplish that :

clang -x c frontend/lexer.mll -E -P -o frontend/gen/lexer.mll

This invokes clang; sets the language it C (-x c); gives your file; asks for preprocessing only, no compile or link (-E); no line info in the output (-P), stores it in frontend/gen/lexer.mll

Xcode is an IDE that runs clang. If you are working in ocaml it may not be helpful ti use Xcode since it wouldn't know what to do with ocaml files.

Answers 3

1 - open XCode

2 - Create a new XCode project

3 - choose tab of OSX

4 - choose Application

5 - choose Command Line tool

6 - in next window you have to enter product name etc

7 - and choose c++ as a language

Answers 4

'cpp -P xxx -o yyy' you need it to be -> 'echo "blahblahblah.cpp" > xxx'

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