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use-before-definition analysis: fix checking of set! form

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Treat the RHS of `set!` as escaping to an unknown context, so
that any variables it references are treated as unprotected.
This commit is contained in:
Matthew Flatt 2014-08-01 07:47:03 +01:00
parent 3801fc0432
commit 7d85bccaa2
2 changed files with 15 additions and 2 deletions
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7
pkgs/racket-pkgs/racket-test/tests/racket/letrec.rktl
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@ -88,4 +88,11 @@
y) y)
letrec-exn?) letrec-exn?)
(err/rt-test
(letrec ([a 1]
[b (set! a (lambda () c))]
[c (a)])
c)
letrec-exn?)
(report-errs) (report-errs)

10
racket/src/racket/src/letrec_check.c
View File

@ -1319,13 +1319,19 @@ static Scheme_Object *letrec_check_set(Scheme_Object *o, Letrec_Check_Frame *fra
Scheme_Object *uvars, Scheme_Object *pvars, Scheme_Object *pos) Scheme_Object *uvars, Scheme_Object *pvars, Scheme_Object *pos)
{ {
Scheme_Set_Bang *sb; Scheme_Set_Bang *sb;
Scheme_Object *val; Scheme_Object *val, *rhs_uvars, *rhs_pvars, *rhs_pos;
int position; int position;
sb = (Scheme_Set_Bang *)o; sb = (Scheme_Set_Bang *)o;
val = sb->val; val = sb->val;
val = letrec_check_expr(val, frame, uvars, pvars, pos); /* Treat `set!` as allowing the right-hand side to escape. (We
could do better if `sb->var` is a variable that we know about.) */
rhs_uvars = merge_vars(uvars, pvars);
rhs_pvars = rem_vars(pvars);
rhs_pos = scheme_false;
val = letrec_check_expr(val, frame, rhs_uvars, rhs_pvars, rhs_pos);
sb->val = val; sb->val = val;
if (SAME_TYPE(SCHEME_TYPE(sb->var), scheme_local_type)) { if (SAME_TYPE(SCHEME_TYPE(sb->var), scheme_local_type)) {