CODEWITHSUNDEEP
c++windowscmake
mans
mans

Reputation: 18178

cmake generate error on windows as it uses \ as escape seq

I have something such as this in my cmake:

set(MyLib_SRC $ENV{MyLib_DIR}/MyLib.cpp)
add_library(MyLibrary STATIC ${MyLib_SRC})

but when I ran the cmake, I am getting this error:

CMake Warning (dev) at CMakeLists.txt:97 (add_library):
Syntax error in cmake code when parsing string

D:\New\Development\Lib/myLib.cpp

Invalid escape sequence \N

Policy CMP0010 is not set: Bad variable reference syntax is an error.  Run
"cmake --help-policy CMP0010" for policy details.  Use the cmake_policy
command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

I read this OS answer cmake parse error :Invalid escape sequence \o but How can I chang the macro (which macro!) to a function?

The value of env variable is 

MyLib_DIR=D:\New\Development\Lib

Upvotes: 7

Views: 9575

Answers (3)

Kevin
Kevin

Reputation: 18303

As indicated in Angew's answer, the backslashes in your environment variable are being interpreted as escape sequences. As of CMake 3.20, there are a host of path manipulation tools provided by the cmake_path command. Using the SET option, this command will convert the input into a CMake path with forward-slashes (/):

cmake_path(SET MyLib_SRC $ENV{MyLib_DIR}/MyLib.cpp)
add_library(MyLibrary STATIC ${MyLib_SRC})

The MyLib_SRC variable will now contain forward-slashes:

D:/New/Development/Lib/MyLib.cpp

Upvotes: 6

Angew is no longer proud of SO
Angew is no longer proud of SO

Reputation: 171167

The problem is that $ENV{MyLib_DIR} expands the environment variable verbatim, including the backslashes used as path separators. These can then get re-interpreted as escape sequences.

What you want to do is convert the path to CMake's internal format before handling it in CMake code:

file(TO_CMAKE_PATH $ENV{MyLib_DIR} MyLib_DIR)

set(MyLib_SRC ${MyLib_DIR}/MyLib.cpp)
add_library(MyLibrary STATIC ${MyLib_SRC})

Upvotes: 17

Archie
Archie

Reputation: 2672

I suppose cmake always expects UNIX-style path. So, what I do is

set(MayLib_PATH $ENV{MyLib_DIR})
string(REPLACE "\\" "/" MayLib_PATH "${MayLib_PATH}")

Upvotes: 2

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