问题
I am using CMake to build my project and I have the following line:
include_directories(${LLVM_INCLUDE_DIRS})
which, after evaluating LLVM_INCLUDE_DIRS, evaluates to:
include_directories(C:\Program Files\LLVM\include)
The problem is that this is being considered two include directories, "C:\Program" and "Files\LLVM\include".
Any idea how can I solve this problem? I tried using quotation marks, but it didn't work.
EDIT: It turned out that the problem is in the file llvm-3.0\share\llvm\cmake\LLVMConfig.cmake. I enclosed the following paths with quotation marks and the problem was solved:
set(LLVM_INSTALL_PREFIX C:/Program Files/LLVM)
set(LLVM_INCLUDE_DIRS ${LLVM_INSTALL_PREFIX}/include)
set(LLVM_LIBRARY_DIRS ${LLVM_INSTALL_PREFIX}/lib)
回答1:
This is more likely to be an error at the point where LLVM_INCLUDE_DIRS is set rather than a problem with include_directories.
To check this, try calling include_directories("C:\\Program Files\\LLVM\\include") - it should work correctly.
The problem seems to be that LLVM_INCLUDE_DIRS was constructed without using quotation marks. Try for example running this:
set(LLVM_INCLUDE_DIRS C:\\Program Files\\LLVM\\include)
message("${LLVM_INCLUDE_DIRS}")
set(LLVM_INCLUDE_DIRS "C:\\Program Files\\LLVM\\include")
message("${LLVM_INCLUDE_DIRS}")
The output is:
C:\Program;Files\LLVM\include
C:\Program Files\LLVM\include
Note the semi-colon in the first output line. This is a list with 2 items.
So the way to fix this is to modify the way in which LLVM_INCLUDE_DIRS is created.
回答2:
In CMake,
- whitespace is a list separator (like
;), - evaluating variable names basically replaces the variable name with its content and
\is an escape character (to get the symbol, it needs to be escaped as well)
So, in your example, include_directories(C:\\Pogram Files\\LLVM\\include) is the same as
include_directories( C:\\Program;Files\\LLVM\\include)
that is, a list with two items. To avoid this, either
escape the whitespace as well:
include_directories( C:\\Program\ Files\\LLVM\\include)orsurround the path with quotation marks:
include_directories( "C:\\Program Files\\LLVM\\include")
Obviously, the second option is the better choice as it is
- simpler and easier to read and
can be used with variable evaluation like in your example (since the result of the evaluation is then surrounded by quotation marks and thus, treated a single item)
include_directories("${LLVM_INCLUDE_DIRS}")
This works as well, if LLVM_INCLUDE_DIRS is a list of multiple directories because the items in this list will then be explicitly separated by ; so that there is no need for unquoted whitespace as implicit list item separator.
Side note: When using hard-coded path-names (for whatever reason) in my CMake files, I usually uses forward slashes as directory separators as this works on Windows as well and avoids the need to escape all backslashes.
来源：https://stackoverflow.com/questions/9964775/using-cmakes-include-directories-command-with-white-spaces