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Correctly detect infinite recursion in function application

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If we're evaluating some application ‘v = f x’, we can't store ‘f’
temporarily in ‘v’, because if ‘f x’ refers to ‘v’, it will get ‘f’
rather than an infinite recursion error.

Unfortunately, this breaks the tail call optimisation introduced in
c897bac549.

Fixes #217.
This commit is contained in:
Eelco Dolstra 2014-02-27 21:47:59 +01:00
parent 29cde917fe
commit c9f6232304
1 changed files with 4 additions and 2 deletions
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6
src/libexpr/eval.cc
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@ -779,8 +779,10 @@ void ExprLambda::eval(EvalState & state, Env & env, Value & v)
void ExprApp::eval(EvalState & state, Env & env, Value & v) void ExprApp::eval(EvalState & state, Env & env, Value & v)
{ {
e1->eval(state, env, v); /* FIXME: vFun prevents GCC from doing tail call optimisation. */
state.callFunction(v, *(e2->maybeThunk(state, env)), v); Value vFun;
e1->eval(state, env, vFun);
state.callFunction(vFun, *(e2->maybeThunk(state, env)), v);
} }