[analysis][NFC] Use C++20 concepts for Lattice (#6027)

Replace the static assertions ensuring that Lattice types have the necessary
operations with a C++20 concept called `Lattice`. To avoid name conflicts with
the new concept, rename existing type parameters named `Lattice` to `L`. When
not building with C++20, `Lattice` is a macro that resolves to `typename` so the
code continues compiling and has the same behavior, but without any eager checks
of the requirements on lattices.

Add a new C++20 builder to CI to ensure that future changes compile with both
C++17 and C++20. Once we switch to C++20 by default, the new builder can be
removed. Update the lint builder to use a recent clang-format that understands
concepts.

1 files changed, 6 insertions, 3 deletions

diff --git a/scripts/clang-format-diff.sh b/scripts/clang-format-diff.sh
index 6c7144f58..d0046e8cd 100755
--- a/scripts/clang-format-diff.sh
+++ b/scripts/clang-format-diff.sh
@@ -11,14 +11,17 @@ else
   BRANCH="@{upstream}"
 fi
 
+LLVM_VERSION=${LLVM_VERSION:=17}
+
 MERGE_BASE=$(git merge-base $BRANCH HEAD)
-FORMAT_MSG=$(git clang-format $MERGE_BASE -q --diff)
+FORMAT_ARGS="--binary=clang-format-${LLVM_VERSION} ${MERGE_BASE}"
+FORMAT_MSG=$(git clang-format ${FORMAT_ARGS} -q --diff)
 if [ -n "$FORMAT_MSG" -a "$FORMAT_MSG" != "no modified files to format" ]
 then
-  echo "Please run git clang-format before committing, or apply this diff:"
+  echo "Please run git clang-format with clang-format-${LLVM_VERSION} before committing, or apply this diff:"
   echo
   # Run git clang-format again, this time without capruting stdout.  This way
   # clang-format format the message nicely and add color.
-  git clang-format $MERGE_BASE -q --diff
+  git clang-format ${FORMAT_ARGS} -q --diff
   exit 1
 fi