Flycheck Files

See the full changelog for more information. The flycheck-32 branch was originally frozen in May 2020.

Highlights

• Many checkers and compiler, such as ocaml, rust, eslint, and others, include end-line and end-column information. Flycheck can now highlight the exact region that they report. Authors of checker definitions can use the new :end-line and :end-column arguments in flycheck-error-new, or the new end-line and end-column fields in error patterns. [GH-1400]

• Errors that checkers return for other files will now be displayed on the first line of the current buffer instead of begin discarded. The error list indicates which file each error came from, and navigation moves automatically moves between files. This change helps with compiled languages, where an error in another file may cause the current file to be considered invalid. Variables flycheck-relevant-error-other-file-show and flycheck-relevant-error-other-file-minimum-level control this behavior. [GH-1427]

• Flycheck can now draw error indicators in margins in addition to fringes. Margins can contain arbitrary characters and images, not just monochrome bitmaps, allowing for a better experience on high-DPI screens. flycheck-indication-mode controls this behavior, and flycheck-set-indication-mode can be used to automatically adjust the fringes and margins. Additionally, Flycheck's will now use high-resolution fringe bitmaps if the fringe is wide enough [GH-1742, GH-1744]

• Error highlighting is now configurable, using the new flycheck-highlighting-style variable: instead of applying level-dependent faces (typically with wavy underlines), Flycheck can now insert delimiters around errors, or mix styles depending on how many lines an error covers. Additionally, stipples are added in the fringes to indicate errors that span multiple lines. [GH-1743]

New features and improvements

• Flycheck can now trigger a syntax check automatically after switching buffers, using the idle-buffer-switch option in flycheck-check-syntax-automatically. This is useful when errors in a file are due to problems in a separate file. Variables flycheck-idle-buffer-switch-delay and flycheck-buffer-switch-check-intermediate-buffers control the functionality. [GH-1297]
• Flycheck will now use Emacs' native XML parsing when libXML fails. This behavior can be changed by customizing flycheck-xml-parser. [GH-1349]
• flycheck-verify-setup now shows more clearly which checkers will run in the buffer, and which are misconfigured. [GH-1478]
• Flycheck now locates checker executables using a customizable function, flycheck-executable-find. The default value of this function allows relative paths (set e.g. in file or dir-local variables) in addition to absolute paths and executable names. [GH-1485]
• Checkers that report error positions as a single offset from the start of the file can use the new flycheck-error-new-at-pos constructor instead of converting that position to a line and a column. [GH-1400]
• Config-file variables can now be set to a list of file names. This is useful for checkers like mypy which don't run correctly when called from a subdirectory without passing an explicit config file. [GH-1711]
• Thanks to algorithmic improvements in error reporting, Flycheck is now much faster in large buffers. [GH-1750]

New syntax checkers:

• Awk with gawk [GH-1708]
• Bazel with bazel-buildifier [GH-1613]
• CUDA with cuda-nvcc [GH-1508]
• CWL with schema-salad-tool [GH-1361]
• Elixir with credo [GH-1062]
• JSON with json-jq [GH-1568]
• Jsonnet with jsonnet [GH-1345]
• MarkdownLint CLI with markdownlint [GH-1366]
• mypy with python-mypy [GH-1354]
• Nix with nix-linter [GH-1530]
• Opam with opam lint [GH-1532]
• protobuf-prototool with prototool [GH-1591]
• Rust with rust-clippy [GH-1385]
• Ruumba with eruby-ruumba [GH-1616]
• Staticcheck with go-staticheck [GH-1541]
• terraform with terraform fmt, tflint [GH-1586]
• Tcl with nagelfar [GH-1365]
• Text prose with textlint [GH-1534]
• VHDL with ghdl [GH-1160]

Checker improvements:

• python-pylint and python-flake8 are now invoked with python -c, to make it easier to change between Python 2 and Python 3. [GH-1113]
• Add flycheck-perl-module-list to use specified modules when syntax checking code with the perl checker. [GH-1207]
• rust-cargo now uses cargo check and cargo test. [GH-1289]
• Add flycheck-ghc-stack-project-file for the haskell-stack-ghc checker. [GH-1316]
• Add flycheck-cppcheck-suppressions-file to pass a suppressions file to cppcheck. [GH-1329]
• Add --force-exclusion flag to rubocop command. [GH-1348]
• Flycheck now uses ESLint's JSON output instead of checkstyle XML. [GH-1350]
• Add flychjeck-eslint-args to pass arguments to javascript-eslint. [GH-1360]
• Flycheck will now execute rubocop from the directory where a Gemfile is located. If a Gemfile does not exist, the old behaviour of running the command from the directory where .rubocop.yml is found will be used. [GH-1368]
• Add flycheck-sh-bash-args to pass arguments to sh-bash. [GH-1439]
• haskell-stack-ghc will not try to install GHC anymore. [GH-1443]
• Add flycheck-ghdl-ieee-library to select which standard IEEE library to use for ghdl. [GH-1547]
• The javascript-eslint checker now supports typescript-mode by default.
• Add flycheck-erlang-rebar3-profile to select which profile to use when compiling erlang with rebar3. [GH-1560]
• Add flycheck-relevant-error-other-file-show to avoid showing errors from other files. [GH-1579]
• The nix-linter checker now has an error explainer. [GH-1586]
• The Emacs Lisp checker can now run in buffers not backed by files. [GH-1695]

Breaking changes

• Remove the javascript-jscs checker. [GH-1024]
• Remove the elixir-dogma checker. [GH-1450]
• rust-cargo now requires Rust 1.17 or newer. [GH-1289]
• rust now requires 1.18 or newer. [GH-1501]
• Rename flycheck-cargo-rustc-args to flycheck-cargo-check-args. [GH-1289]
• rust-cargo does not use the variable flycheck-rust-args anymore. [GH-1289]
• Improve detection of default directory for haskell-ghc to consider hpack project files. [GH-1435]
• Replace go tool vet with go vet. [GH-1548]
• Remove the deprecated go-megacheck checker, which is replaced by go-staticcheck. [GH-1583]

Many thanks to all the people who contributed for this release 🎉