forked from OSchip/llvm-project
48cd9d9dd8
Summary: If the output filename was specified as "-", the ToolOutputFile class would create a brand new raw_ostream object referring to the stdout. This patch changes it to reuse the llvm::outs() singleton. At the moment, this change should be "NFC", but it does enable other enhancements, like the automatic stdout/stderr synchronization as discussed on D80803. I've checked the history, and I did not find any indication that this class *has* to use a brand new stream object instead of outs() -- indeed, it is special-casing "-" in a number of places already, so this change fits the pattern pretty well. I suspect the main reason for the current state of affairs is that the class was originally introduced (r111595, in 2010) as a raw_fd_ostream subclass, which made any other solution impossible. Another potential benefit of this patch is that it makes it possible to move the raw_ostream class out of the business of special-casing "-" for stdout handling. That state of affairs does not seem appropriate because "-" is a valid filename (albeit hard to access with a lot of command line tools) on most systems. Handling "-" in ToolOutputFile seems more appropriate. To make this possible, this patch changes the return type of llvm::outs() and errs() to raw_fd_ostream&. Previously the functions were constructing objects of that type, but returning a generic raw_ostream reference. This makes it possible for new ToolOutputFile and other code to use raw_fd_ostream methods like error() on the outs() object. This does not seem like a bad thing (since stdout is a file descriptor which can be redirected to anywhere, it makes sense to ask it whether the writing was successful or if it supports seeking), and indeed a lot of code was already depending on this fact via the ToolOutputFile "back door". Reviewers: dblaikie, JDevlieghere, MaskRay, jhenderson Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D81078 |
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