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special-form heads are not shadowable

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Found in a read/eval review: a local named like a special form wrongly took
over operator position. (let [if (fn ...)] (if true 1 2)) returned the fn, but
per spec section 3 (and the reference) special-form heads are not shadowable;
only macros are. Two fixes: drop the (not shadowed) guard on the special-form
branch of analyze-list (so an (if ...) head is always the special), and prefix
a local whose name is a Scheme keyword when emitting (so a value local legally
named if does not shadow the (if ...) the back end emits). Value-position
locals named if/or/case still work.
This commit is contained in:
Yogthos 2026-06-22 01:01:53 -04:00
parent f18ae3bd46
commit 212cd0399a
5 changed files with 106 additions and 81 deletions
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7
test/chez/unit.edn
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@ -449,4 +449,11 @@
{:suite "walk" :expr "(do (require (quote [clojure.walk :as w])) (w/postwalk-replace {:a 1 :b 2} '(:a [:b :a])))" :expected "(1 [2 1])"}
{:suite "walk" :expr "(do (require (quote [clojure.walk :as w])) (w/postwalk-replace {1 :one} [1 2 1]))" :expected "[:one 2 :one]"}
{:suite "walk" :expr "(do (require (quote [clojure.template :as t])) (t/apply-template '[x y] '(+ x y) '(1 2)))" :expected "(+ 1 2)"}
{:suite "shadowing" :expr "(let [if (fn [a b c] :L)] (if true 1 2))" :expected "1"}
{:suite "shadowing" :expr "(let [quote (fn [_] :L)] (quote x))" :expected "x"}
{:suite "shadowing" :expr "(let [if 5] if)" :expected "5"}
{:suite "shadowing" :expr "((fn [if] (+ if 1)) 7)" :expected "8"}
{:suite "shadowing" :expr "(let [when (fn [a b] :local)] (when 1 2))" :expected ":local"}
{:suite "macroexpand" :expr "(do (when true (defmacro m6 [x] `(* ~x 2))) (m6 3))" :expected "6"}
{:suite "macroexpand" :expr "(letfn [(ev? [n] (if (zero? n) true (od? (dec n)))) (od? [n] (if (zero? n) false (ev? (dec n))))] (ev? 10))" :expected "true"}
]