How to split strings across multiple lines in CMake?

Question

I usually have a policy in my project, to never create lines in text files that exceed a line length of 80, so they are easily editable in all kinds of editors (you know the

Answer 1

There is no way to split a string literal across multiple lines in CMakeLists.txt files or in CMake scripts. If you include a newline within a string, there will be a literal newline in the string itself.

# Don't do this, it won't work, MYPROJ_VERSION will contain newline characters:
set(MYPROJ_VERSION "${VERSION_MAJOR}.
  ${VERSION_MINOR}.${VERSION_PATCH}-
  ${VERSION_EXTRA}")

However, CMake uses whitespace to separate arguments, so you can change a space that's an argument separator into a newline anywhere you like, without changing the behavior.

You could re-phrase this longer line:

set(MYPROJ_VERSION "${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_PATCH}-${VERSION_EXTRA}")

as these two shorter lines:

set(MYPROJ_VERSION
  "${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_PATCH}-${VERSION_EXTRA}")

They are entirely equivalent.