Revert commit 5b45a3d0ce (CheckCompilerFlag: Match the Clang "argument
unused" output for all languages, 2023-01-23, v3.26.0-rc1~38^2). It
broke existing projects that were silently tolerating unrelated unused
arguments in their checks for C and CXX. For example, using
`CFLAGS=-nostdinc` or `CXXFLAGS=-nostdinc++` causes those flags to be
used when driving the linker as well, and Clang warns they are unused in
that case.
Add a test case covering the now-restored behavior.
Fixes: #24591
Improve detection of missing compiler flags: move "argument unused
during compilation: .*" pattern from language-specific branches into
the common list.
Per-source copyright/license notice headers that spell out copyright holder
names and years are hard to maintain and often out-of-date or plain wrong.
Precise contributor information is already maintained automatically by the
version control tool. Ultimately it is the receiver of a file who is
responsible for determining its licensing status, and per-source notices are
merely a convenience. Therefore it is simpler and more accurate for
each source to have a generic notice of the license name and references to
more detailed information on copyright holders and full license terms.
Our `Copyright.txt` file now contains a list of Contributors whose names
appeared source-level copyright notices. It also references version control
history for more precise information. Therefore we no longer need to spell
out the list of Contributors in each source file notice.
Replace CMake per-source copyright/license notice headers with a short
description of the license and links to `Copyright.txt` and online information
available from "https://cmake.org/licensing". The online URL also handles
cases of modules being copied out of our source into other projects, so we
can drop our notices about replacing links with full license text.
Run the `Utilities/Scripts/filter-notices.bash` script to perform the majority
of the replacements mechanically. Manually fix up shebang lines and trailing
newlines in a few files. Manually update the notices in a few files that the
script does not handle.
In commit v3.0.0-rc1~551^2~1 (Check*CompilerFlag: make C and CXX modules
share most error patterns, 2013-08-08) a pattern containing a ';' was
moved out of a ""-quoted argument and into a variable. CMake flattens
the containing list and breaks the pattern. Use a '.' to match ';'.
This simplifies maintenance as most patterns will be for both modules and may
be added at a central place.
While at it add error patterns for XL and BCC.
