Summary:
Error handling in liblldCore and the Darwin toolchain prints to an
output stream. A TODO in the project explained that a diagnostics
interface resembling Clang's should be added.
For now, the simple diagnostics interface defined in liblldCommon seems
like an improvement. It prints colors when they're available, uses locks
for thread-safety, and abstracts away the `"error: "` and newline
literal strings that litter the Darwin toolchain code.
To use the liblldCommon error handler, a link dependency is added to
the liblldDriver library.
Test Plan:
1. check-lld
2. Invoke `ld64.lld -r` in a terminal that supports color output.
Confirm that "ld64.lld: error: -arch not specified and could not be inferred"
is output, and that the "error:" is colored red!
Reviewers: ruiu, smeenai
Reviewed By: ruiu
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D47998
llvm-svn: 334466
b9f7f4b87c