From 98ef11677c43db9aa669768d9f0cbec704e8831c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 10 Dec 2019 13:32:30 +0100
Subject: [PATCH] EvalState::callFunction(): Make FunctionCallTrace use less
stack space
The FunctionCallTrace object consumes a few hundred bytes of stack
space, even when tracing is disabled. This was causing stack overflows:
$ nix-instantiate '<nixpkgs> -A texlive.combined.scheme-full --dry-run
error: stack overflow (possible infinite recursion)
This is with the default stack size of 8 MiB.
Putting the object on the heap reduces stack usage to < 5 MiB.
---
src/libexpr/eval.cc | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index e2070d546..4be4cfeea 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1091,10 +1091,9 @@ void EvalState::callPrimOp(Value & fun, Value & arg, Value & v, const Pos & pos)
void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & pos)
{
- std::optional<FunctionCallTrace> trace;
- if (evalSettings.traceFunctionCalls) {
- trace.emplace(pos);
- }
+ std::unique_ptr<FunctionCallTrace> trace;
+ if (evalSettings.traceFunctionCalls)
+ trace = std::make_unique<FunctionCallTrace>(pos);
forceValue(fun, pos);
--
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