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Fix crash bug in closure capturing.

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This commit is contained in:
Bob Nystrom
2014-04-24 17:52:53 -07:00
parent 80a4eb8c9c
commit feb9f7cb53
2 changed files with 15 additions and 2 deletions
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4
src/wren_vm.c
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@ -218,7 +218,7 @@ static Upvalue* captureUpvalue(WrenVM* vm, ObjFiber* fiber, int slot)
Upvalue* prevUpvalue = NULL; Upvalue* prevUpvalue = NULL;
Upvalue* upvalue = fiber->openUpvalues; Upvalue* upvalue = fiber->openUpvalues;
// Walk towards the bottom of the stack until we find a previously existsing // Walk towards the bottom of the stack until we find a previously existing
// upvalue or pass where it should be. // upvalue or pass where it should be.
while (upvalue != NULL && upvalue->value > local) while (upvalue != NULL && upvalue->value > local)
{ {
@ -227,7 +227,7 @@ static Upvalue* captureUpvalue(WrenVM* vm, ObjFiber* fiber, int slot)
} }
// Found an existing upvalue for this local. // Found an existing upvalue for this local.
if (upvalue->value == local) return upvalue; if (upvalue != NULL && upvalue->value == local) return upvalue;
// We've walked past this local on the stack, so there must not be an // We've walked past this local on the stack, so there must not be an
// upvalue for it already. Make a new one and link it in in the right // upvalue for it already. Make a new one and link it in in the right

13
test/closure/close_over_later_variable.wren Normal file
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@ -0,0 +1,13 @@
// This is a regression test. There was a bug where if an upvalue for an
// earlier local (here "a") was captured *after* a later one ("b"), then Wren
// would crash because it walked to the end of the upvalue list (correct), but
// then didn't handle not finding the variable.
new Fn {
var a = "a"
var b = "b"
new Fn {
IO.print(b) // expect: b
IO.print(a) // expect: a
}.call
}.call