Support editorconfig

[Freed-Wu]

Fix #1843, Fix #2128

EditorConfig cores shall accept and report all syntactically valid key-value pairs, even if the key is not defined in this specification.
EditorConfig plugins shall ignore unrecognized keys and invalid/unsupported values.

So we can use .editorconfig or global ~/.config/editorconfig.ini :

[{build,*.subpackage}.sh]
shellcheck.disable=SC2034

[{*.ebuild,*.eclass,*.conf,color.map,.devscripts,*.mdd}]
shellcheck.shell=bash
shellcheck.disable=SC2034

[{PKGBUILD,*.install}]
shellcheck.shell=bash
shellcheck.disable=SC2034,SC2154

[APKBUILD]
shellcheck.shell=sh
shellcheck.disable=SC2034,SC2154

Refer termux-language-server for filenames.

Add a command line option --file-name=FILE to specify the file name when input is read from stdin. This allows bash-language-server

shellcheck --file-name=PKGBUILD -

Final result:

PS: If someone want to realize #1844 #356 , can extend the config:

[{PKGBUILD,*.install}]
shellcheck.shell=bash
shellcheck.sourcefile=/the/path/of/PKGBUILD.d.sh

PKGBUILD.d.sh:

# avoid SC2154
export pkgdir srcdir
# avoid SC2034
export pkgver # ...

[e-kwsm]

Without .editorconfig, shellcheck issues SC2148:

$ echo 'pushd foo || exit' > x
$ shellcheck x

In x line 1:
pushd foo || exit
^-- SC2148 (error): Tips depend on target shell and yours is unknown. Add a shebang or a 'shell' directive.

For more information:
  https://www.shellcheck.net/wiki/SC2148 -- Tips depend on target shell and y...

But when .editorconfig specifies a wrong shell, SC2148 is not issued

$ > .editorconfig cat << 'EOF'
root = true
[*]
shellcheck.shell = zsh
# XXX: zsh is not supported
EOF
$ shellcheck     x  # no warning
$ shellcheck - < x  # stdin, neither

[e-kwsm]

root =

→ No warnings/errors are issued.

root = true
[*]
shellcheck.shell =

→ SC1134 is issued but the location is incorrect

$ shellcheck -s bash x

In x line 1:
pushd foo || exit
^-- SC1134 (error): Failed to process x, line 1:  Fix any mentioned problems and try again.

For more information:
  https://www.shellcheck.net/wiki/SC1134 -- Failed to process x, line 1:  Fix...

root = true
[*]
shellcheck.disable = abc

→ the same as above