cmake_path(IS_PREFIX) and $<PATH:IS_PREFIX> treated an empty path as a
prefix of every path, including another empty path, following
std::filesystem::path. A prefix that is empty because a variable was
set to an empty value, or because a generator expression argument
expanded to nothing, therefore satisfied a check meant to reject it.
Return false for an empty prefix, in cmCMakePath::IsPrefix so that every
caller shares one implementation and both the plain and NORMALIZE forms
are covered. Normalizing an empty path leaves it empty, so no separate
handling of NORMALIZE is needed. Unlike the component comparison, which
follows std::filesystem::path deliberately, IsPrefix has no counterpart
in the standard: it borrows path iteration but the predicate itself is
defined by CMake, so an empty prefix is a gap to fill rather than a
standard answer to override.
Add policy CMP0223 and restore the old result behind it at the two
released surfaces. The other callers of IsPrefix, source_group() and
the Makefile generator's source classification, take the new behavior
ungated: source_group() rejects an empty TREE argument before reaching
it, and the generator passes the source and binary directories.
The if(PATH_IS_PREFIX) operator, new in this same release, follows the
policy too rather than simply taking the new behavior, so that it agrees
with cmake_path(IS_PREFIX) in every policy state and the parity
assertions in its test hold unconditionally.
Fixes: #28077
Run the `clang-format.bash` script to update all our C and C++ code to a
new style defined by `.clang-format`, now with "east const" enforcement.
Use `clang-format` version 18.
* If you reached this commit for a line in `git blame`, re-run the blame
operation starting at the parent of this commit to see older history
for the content.
* See the parent commit for instructions to rebase a change across this
style transition commit.
Issue: #26123
Mickaël Germain
Ben Boeckel
Kitware Robot
Marc Chevrier
Brad King
Vitaly Stakhovsky
Oleksandr Koval