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Add legacy-multival/legacy-multival-case lint and fix.

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As of Fennel 1.6.0, parens in destructuring is deprecated, and we want
to make it easy for people to convert to using table destructuring
instead since it's optimized to compile to the same thing.
This commit is contained in:
Phil Hagelberg 2025-10-06 11:26:02 -07:00
parent 467454f4e2
commit 2b2c31c577
3 changed files with 93 additions and 2 deletions
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5
src/fennel-ls/compiler.fnl
View File

@ -70,6 +70,7 @@ identifiers are declared / referenced in which places."
;; The useful information being recorded:
(let [definitions-by-scope (doto {} (setmetatable has-tables-mt))
definitions {} ; symbol -> binding
multi-binds {}
compile-diagnostics {} ; [diagnostic]
references {} ; symbol -> references
macro-refs {} ; symbol -> macro
@ -140,6 +141,9 @@ identifiers are declared / referenced in which places."
(recurse binding [] 0))
(λ define [?definition binding scope ?opts]
;; just storing lists for now; can add others if a lint needs them
(when (list? binding)
(table.insert multi-binds {:left binding :right ?definition}))
(for-each-binding-in binding ?definition
(fn [symbol ?definition keys ?multival]
(when (not (or (list? symbol) (multisym? symbol)))
@ -462,6 +466,7 @@ identifiers are declared / referenced in which places."
(set file.scopes scopes)
(set file.definitions definitions)
(set file.definitions-by-scope definitions-by-scope)
(set file.multi-binds multi-binds)
(set file.compile-errors compile-diagnostics)
(set file.references references)
(set file.require-calls require-calls)

66
src/fennel-ls/lint.fnl
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@ -798,6 +798,72 @@ You can read more about how to add lints in docs/linting.md"
{:message "indexing a table with 0; did you forget that Lua is 1-indexed?"
: ast}))})
(add-lint :legacy-multival
{:what-it-does "Detects usage of legacy (paren) multival destructuring."
:why-care? "It's more consistent to use table destructuring."
:type :other
:example "```fnl
(let [input \"whatever\"
(v1 v2) (input:match \"([aeiou]).*([aeiou])\")]
(print :vowels v1 v2))
```
Instead, use:
```fnl
(let [input \"whatever\"
[v1 v2] [(input:match \"([aeiou]).*([aeiou])\")]]
(print :vowels v1 v2))
```"
:since "0.2.2-dev"
:disabled true
:impl (fn [server file]
(each [_ {: left : right} (ipairs file.multi-binds)]
(when (and (list? left) (. file.lexical left))
(coroutine.yield
{:message "Legacy multival destructure can be replaced with table destructure."
:ast left
:fix #{:title "Replace legacy multival destructure with table."
:changes [{:range (message.ast->range server file left)
:newText (-> (tostring left)
(: :gsub "^%(" "[")
(: :gsub "%)$" "]"))}
{:range (message.ast->range server file right)
:newText (.. "[" (tostring right) "]")}]}}))))})
(fn match-call? [[callee &as ast]]
(and (list? ast)
(case (tostring callee)
:case true :match true :case-try true :match-try true)))
(add-lint :legacy-multival-case
{:what-it-does "Detects usage of legacy (paren) multival destructuring in pattern match."
:why-care? "It's more consistent to use table destructuring."
:type :macro-call
:since "0.2.2-dev"
:disabled true
:example "```fnl
(case (input:match \"([aeiou]).*([aeiou])\")
(v1 v2) (print \"Two vowels:\" v1 v2)
_ (print \"Less than two\"))
```
Instead, use:
(case [(input:match \"([aeiou]).*([aeiou])\")]
[v1 v2] (print \"Two vowels:\" v1 v2)
_ (print \"Less than two\"))
"
:impl (fn [_server _file ast]
(if (match-call? ast)
(faccumulate [r nil i 3 (length ast) 2 &until r]
(if (and (list? (. ast i))
(not (sym? (. ast i 1) :catch))
(not (sym? (. ast i 1) :where)))
;; would be nice to get fixes here but it needs to be smart
;; about case (fix val+every pattern) vs case-try (fix
;; pattern and previous body)
{:message "Legacy multival destructure can be replaced with table destructure."
:ast (. ast i)}))))})
(add-lint :invalid-flsproject-settings
{:what-it-does
"Checks if the flsproject file's settings are valid."

24
test/lint.fnl
View File

@ -38,11 +38,18 @@
:escape-newlines? true})))
(table.remove diagnostics i)))))
(macro check-form [lints form expected ?unexpected]
`(check {:main.fnl ,(view form) :flsproject.fnl ,(view {: lints})}
,expected ,?unexpected))
(fn assert-ok [file-contents]
(let [{: uri : client} (create-client file-contents)
[{:result {:items diagnostics}}] (client:diagnostic uri)]
(faith.= nil (next diagnostics) (view diagnostics))))
(macro assert-ok-form [lints form]
`(assert-ok {:main.fnl ,(view form) :flsproject.fnl ,(view {: lints})}))
(fn test-unused []
(check "(local x 10)"
[{:message "unused definition: x"
@ -414,7 +421,19 @@
(assert-ok (add-opts "(. math :0)")))
nil)
(fn test-legacy-multival []
(check-form {:legacy-multival true}
(let [(x y z) (table.unpack [10 9 8])] (+ x y z))
[{:message "Legacy multival destructure can be replaced with table destructure."
:range {:end {:character 13 :line 0} :start {:character 6 :line 0}}}])
(check-form {:legacy-multival-case true}
(case (table.unpack [9 0 3]) (n x) (print :yes n x))
[{:message "Legacy multival destructure can be replaced with table destructure."}])
(assert-ok-form {:legacy-multival-case true}
(case-try (values 1 2 3)
nil (print :lol)
(where (or a [a])) (print (+ a 3))
(catch (x) x))))
{: test-unused
: test-ampersand
@ -434,4 +453,5 @@
: test-arg-count
: test-duplicate-keys
: test-nested-associative-operator
: test-zero-indexed}
: test-zero-indexed
: test-legacy-multival}