Erlang中有意思的bug
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代码中常有一些很搞笑的bug，如下面的一行代码被调用两次（Erlang beam）
commit f667e4a47b07b07ed035073b94d699ff5fe0ba9bAuthor: Jovi Zhang <bookjovi@gmail.com>Date: Fri Dec 2 16:19:22 2011 +0100 erts: Remove duplicate erts_unblock_fpe The second function erts_unblock_fpe is not needed in here.diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.cindex c2cc035..759621d 100644--- a/erts/emulator/beam/io.c+++ b/erts/emulator/beam/io.c@@ -644,7 +644,6 @@ erts_open_driver(erts_driver_t* driver, /* Pointer to driver. */ name, opts); erts_unblock_fpe(fpe_was_unmasked); port->caller = NIL;- erts_unblock_fpe(fpe_was_unmasked); if (IS_TRACED_FL(port, F_TRACE_SCHED_PORTS)) { trace_sched_ports_where(port, am_out, am_start); }?已经unblock了一次，结果又unblock了一次，应该是代码作者的粗心导致的，有意思的是这行代码在erlang的git初始版本中就有了，存活了3年甚至更久，而且经过无数个人的review竟也没有发现。
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在Linux kernel中也有这样的低级错误，记得以前看见过在pipe.c中的一个patch，作者本意是a=b，结果写成了b=a，那个错误存在了十几年，为什么没有被发现呢？因为那个代码分支一般很难跑进去！
commit e5953cbdff26f7cbae7eff30cd9b18c4e19b7594Author: Nicolas Kaiser <nikai@nikai.net>Date: Thu Oct 21 14:56:00 2010 +0200 pipe: fix failure to return error code on ->confirm() The arguments were transposed, we want to assign the error code to 'ret', which is being returned. Signed-off-by: Nicolas Kaiser <nikai@nikai.net> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>diff --git a/fs/pipe.c b/fs/pipe.cindex 279eef9..37eb1eb 100644--- a/fs/pipe.c+++ b/fs/pipe.c@@ -382,7 +382,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov, error = ops->confirm(pipe, buf); if (error) { if (!ret)- error = ret;+ ret = error; break; }?结论：仔细review你的代码，尽管你写了无数行的代码，尽管你已是一个公认的技术专家，你的代码中仍有可能存在着一些非常低级的bug.
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