Hi Jiefei,

the change in handling trailing path separators is not on purpose, but is a byproduct of a new implementation of normalizePath, which now handles symbolic links and normalizes case in long path names. It is not documented what happens to trailing separators, and hence portable programs should not depend on it. I don't think it is a property that should be documented/specified. The behavior of normalizePath is way too complicated already and it's result is OS-specific anyway.

In R-devel as well as in 3.6, the trailing separator is preserved when the path does not exist - simply, the original path is returned. When the path does exist, R-devel removes the trailing separator but R 3.6 does not, which is because the underlying Windows API call to implement it is now different. The new behavior reflects what GetFinalPathNameByHandle returns, which is a function now used for normalization also in other language runtimes on Windows. I think the new behavior is better: paths differing only in the trailing separator will be normalized to the same path.

Best
Tomas

On 3/23/20 4:39 PM, Wang Jiefei wrote:
Hi all,

I saw a quite surprising result in the devel R when using the function
*normalizePath*. If the input is a path to a folder, the function returns
an absolute path with/without a slash at the end depending on the existence
of the folder. I know both results are valid on Windows but this behavior
is different than R3.6, I do not know if the change in the devel version is
made on purpose. Here is a minimal example, suppose that the folder
`C:/windows1/` does not exist.

   > normalizePath("C:/windows/", mustWork = FALSE)
[1] "C:\\Windows"
normalizePath("C:/windows1/", mustWork = FALSE)
[1] "C:\\windows1\\"


In R 3.6, the return value always ends with a slash if the input ends with
a slash. From the NEWS file, It seems like there are some changes to
*normalizePath* but none of them should be relevant, it might be an
unintentional result introduced by the update.

Best,
Jiefei

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