[Lldb-commits] [PATCH] D18287: Don't try to redefine the signal() function on Windows

[Zachary Turner via lldb-commits]

zturner created this revision.
zturner added reviewers: amccarth, cameron314.
zturner added a subscriber: lldb-commits.

Windows comes with an extremely limited implementation of `signal` which only supports a few signal values.  Of importance to LLDB is the `SIGINT` value which invokes a callback when the user presses Ctrl+C.  For some reason, we were completely redefining the `signal()` function to intercept `SIGINT` and use our own custom processing of Ctrl+C rather than use the builtin processing of Ctrl+C done by `signal()`.  This is frought with peril for a number of reasons:

1) Depending on order of includes, you could get into a situation where both builtin `signal()` and our own custom `signal()` are defined, leading to multiply defined symbol errors at link time.
2) It leads to a bunch of compiler warnings, since we end up redefining the same constants (e.g. `SIG_DFL` etc) because we were going through hoops to avoid #including the standard headers (even though that doesn't work)
3) The standard implementation of `signal()` actually does exactly what you would expect it to do with regards to Ctrl+C.  In fact, by looking at the source code of the CRT, you can see that for `SIGINT` it actually just calls `SetConsoleCtrlHandler`, which is exactly what our own custom implementation of signal did!  

So, we simply remove all of our custom windows versions of `signal()` and use the builtin implementation.  Code that attempts to call `signal()` with values that are not supported on Windows are handled by preprocessor defines

http://reviews.llvm.org/D18287

Files:
  tools/driver/Driver.cpp
  tools/driver/Platform.cpp
  tools/driver/Platform.h
  tools/lldb-mi/CMakeLists.txt
  tools/lldb-mi/Platform.cpp
  tools/lldb-mi/Platform.h

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