Currently our diagnostics subsystem can emit fix-it hints suggesting edits the user can make to their code to fix warnings/errors, but currently the user must make these edits manually [1].
The following patch kit adds two command-line options with which we can make the changes on behalf of the user: (A) -fdiagnostics-generate-patch emits a diff to stderr, which could potentially be applied using "patch"; it also gives another way to visualize the fix-its. (B) -fdiagnostics-apply-fixits, which writes back the changes to the input files. Patches 1 and 2 are enabling work. Patch 3 is the heart of the kit: a new class edit_context, representing a set of changes to be applied to source file(s). The changes are atomic: all are applied or none [2], and locations are specified relative to the initial inputs (and there's some fiddly logic for fixing up locations so that the order in which edits are applied doesn't matter). Patch 4 uses the edit_context class to add the new options. The kit also unlocks the possibility of writing refactoring tools as gcc plugins, or could be used to build a parser for the output of -fdiagnostics-parseable-fixits. Successfully bootstrapped®rtested the combination of the patches on x86_64-pc-linux-gnu. I believe I can self-approve patch 3, and, potentially patch 4 as part of my "diagnostics maintainer" role, though this is clearly a significant extension of the scope of diagnostics. OK for trunk? (assuming individual bootstraps®rtesting) [1] or use -fdiagnostics-parseable-fixits - but we don't have a way to parse that output format yet [2] the error-handling for write-back isn't great right now, so the claim of atomicity is a stretch; is there a good cross-platform way to guarantee atomicity of a set of filesystem operations? (maybe create the replacements as tempfiles, rename the originals, try to move all the replacements into place, and then unlink the backups, with a rollback involving moving the backups into place) David Malcolm (4): selftest: split out named_temp_file from temp_source_file Improvements to typed_splay_tree Introduce class edit_context Add -fdiagnostics-generate-patch and -fdiagnostics-apply-fixits gcc/Makefile.in | 2 + gcc/common.opt | 8 + gcc/diagnostic-color.c | 8 +- gcc/diagnostic.c | 11 + gcc/diagnostic.h | 7 + gcc/doc/invoke.texi | 28 +- gcc/edit-context.c | 1341 ++++++++++++++++++++ gcc/edit-context.h | 66 + gcc/selftest-run-tests.c | 2 + gcc/selftest.c | 49 +- gcc/selftest.h | 26 +- .../diagnostic-test-show-locus-generate-patch.c | 77 ++ gcc/testsuite/gcc.dg/plugin/plugin.exp | 3 +- gcc/toplev.c | 20 + gcc/typed-splay-tree.c | 79 ++ gcc/typed-splay-tree.h | 67 + 16 files changed, 1770 insertions(+), 24 deletions(-) create mode 100644 gcc/edit-context.c create mode 100644 gcc/edit-context.h create mode 100644 gcc/testsuite/gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c create mode 100644 gcc/typed-splay-tree.c -- 1.8.5.3
