https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84904
Bug ID: 84904
Summary: Implement an option to attempt to auto-apply fix-it
hints
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: other
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Target Milestone: ---
In my original edit_context patch kit I posted a "-fdiagnostics-apply-fixits"
option that would auto-apply fix-it hints:
https://gcc.gnu.org/ml/gcc-patches/2016-08/msg01682.html
...but there was no error-checking.
This is something of a brainstorm:
A really smart implementation of this would directly modify the token stream,
and fix the AST as we go.
Sadly I don't think that doing that would be feasible, for C, at least, so any
implementation is probably going to have to write a file to disk.
(maybe it's doable for C++, given that that has all the tokens in-memory
up-front? but what about the preprocessor?)
Error-handling needs to be perfect: we must *never* lose or corrupt the user's
source code.
Would probably need to be something like:
* write the proposed new code to disk
* verify that it works
* make a backup copy of the old code
* copy the new code into place (various failures here need to be dealt with)
* tell the user where the backup is
* maybe keep the last, say, 10 copies around, with rolling backup (param to
control it)
Further complications:
* fix-it hints could affect multiple files, not just the primary source file
* we might not have write access to some of the files (e.g. headers).
(Reminiscent of fixincludes?)
There could be interaction with the driver: apply the fixes, reinvoke the
compiler, etc. Maybe keep going until we can't fix. If so, could need some
diagnostic-suppression to avoid spamming the user with the same diagnostic over
and over again. Question: if we successfully get the user's code to compile,
but there were errors along the way, do we still generate a .o file?
Maybe "-fixit" is a better name?
