Support LLVM 23 by Vipul-Cariappa · Pull Request #1098 · compiler-research/CppInterOp

Vipul-Cariappa · 2026-08-28T10:07:30Z

This PR enables CppInterOp to be used with LLVM 23.

Review each commit separately; that might be easy. Reading the commit message for the diagnostics change would make it easy to review.

Note: CppJIT currently fails with LLVM 23; it requires llvm/llvm-project#218149. Otherwise, CppJIT itself can be patched temporarily until the LLVM PR lands.

codecov · 2026-08-28T10:12:02Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.52%. Comparing base (9bbdbb2) to head (09fb8c8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1098      +/-   ##
==========================================
- Coverage   87.74%   87.52%   -0.22%     
==========================================
  Files          23       23              
  Lines        6429     6116     -313     
==========================================
- Hits         5641     5353     -288     
+ Misses        788      763      -25

Files with missing lines	Coverage Δ
lib/CppInterOp/Compatibility.h	`84.54% <100.00%> (+2.36%)`	⬆️
lib/CppInterOp/CppInterOp.cpp	`90.59% <100.00%> (+0.04%)`	⬆️
lib/CppInterOp/DynamicLibraryManagerSymbol.cpp	`67.96% <ø> (-2.38%)`	⬇️

... and 17 files with indirect coverage changes

Files with missing lines	Coverage Δ
lib/CppInterOp/Compatibility.h	`84.54% <100.00%> (+2.36%)`	⬆️
lib/CppInterOp/CppInterOp.cpp	`90.59% <100.00%> (+0.04%)`	⬆️
lib/CppInterOp/DynamicLibraryManagerSymbol.cpp	`67.96% <ø> (-2.38%)`	⬇️

... and 17 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

github-actions

clang-tidy made some suggestions

github-actions · 2026-08-28T10:24:10Z


 #include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/ADT/STLForwardCompat.h"
 #include "llvm/ADT/SmallVector.h"


warning: included header STLForwardCompat.h is not used directly [misc-include-cleaner]

Suggested change

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/SmallVector.h"

github-actions · 2026-08-28T10:24:10Z

+// Print anonymous tags as a bare "(anonymous struct)" without the trailing
+// source location. Clang 23 replaced the AnonymousTagLocations bit with the
+// AnonymousTagMode enum stored in AnonymousTagNameStyle.
+inline void SuppressAnonymousTagLocations(clang::PrintingPolicy& Policy) {


warning: no header providing "clang::PrintingPolicy" is directly included [misc-include-cleaner]

lib/CppInterOp/Compatibility.h:12:

- #if CLANG_VERSION_MAJOR < 21 + #include <clang/AST/PrettyPrinter.h> + #if CLANG_VERSION_MAJOR < 21

github-actions · 2026-08-28T10:24:10Z

+#ifdef CPPINTEROP_VALUE_BOX_MOVE
+  auto* Payload = new detail::ValueRefCount(std::move(V));
+#else
+  auto* Payload = new detail::ValueRefCount(V);


warning: initializing non-owner 'detail::ValueRefCount *' with a newly created 'gsl::owner<>' [cppcoreguidelines-owning-memory]

auto* Payload = new detail::ValueRefCount(V); ^

github-actions · 2026-08-28T10:24:10Z

  clang::DiagnosticsEngine& fDiagEngine;
-  bool fOldDiagValue;
+  clang::DiagnosticConsumer* fOldClient;
+  std::unique_ptr<clang::DiagnosticConsumer> fOldOwnedClient;


warning: member variable 'fOldClient' has protected visibility [cppcoreguidelines-non-private-member-variables-in-classes]

sticConsumer* fOldClient; ^

github-actions · 2026-08-28T10:24:10Z

-  bool fOldDiagValue;
+  clang::DiagnosticConsumer* fOldClient;
+  std::unique_ptr<clang::DiagnosticConsumer> fOldOwnedClient;
+  clang::IgnoringDiagConsumer fIgnoringClient;


warning: member variable 'fOldOwnedClient' has protected visibility [cppcoreguidelines-non-private-member-variables-in-classes]

onsumer> fOldOwnedClient; ^

github-actions · 2026-08-28T10:24:10Z

+  std::unique_ptr<clang::DiagnosticConsumer> fOldOwnedClient;
+  clang::IgnoringDiagConsumer fIgnoringClient;
 };
 } // namespace


warning: member variable 'fIgnoringClient' has protected visibility [cppcoreguidelines-non-private-member-variables-in-classes]

sumer fIgnoringClient; ^

mcbarton · 2026-08-28T11:01:42Z

@@ -96,14 +96,14 @@ include(GNUInstallDirs)
  ## Define supported version of clang and llvm

  set(CLANG_MIN_SUPPORTED 20.0)


I think we now have a policy of only supporting the 3 most recent llvm versions. An llvm update PR is normally accompanied with a PR which drops the oldest llvm version.

mcbarton · 2026-08-28T11:02:33Z

@@ -50,6 +50,7 @@ jobs:
          # Ubuntu Arm
          - { name: ubu24-arm-gcc12-llvm22-vg, os: ubuntu-24.04-arm, compiler: gcc-12, clang-runtime: '22', Valgrind: On }


You should probably update the Valgrind jobs to llvm 23. I believe this may have been done in a separate PR though for the llvm 22 upgrade.

mcbarton · 2026-08-28T11:02:51Z

          - { name: ubu24-x86-clang22-llvm22-asan-ubsan, os: ubuntu-24.04, compiler: clang-22, clang-runtime: '22', sanitizer: "Address;Undefined", flavor: asan }
          - { name: ubu24-x86-clang22-llvm22-msan, os: ubuntu-24.04, compiler: clang-22, clang-runtime: '22', sanitizer: "Memory", flavor: msan }


These will also want updating to llvm 23

mcbarton

This PR doesn't update the Emscripten jobs, so we don't know if there has been any regressions there. There was between llvm 21 and 22, and we ended up disabling tests and just accepted the regressions.

mcbarton · 2026-08-28T14:20:43Z

I just realised the only job which has been updated to llvm 23 in the ci is the Ubuntu x86 job, so there is no check that nothing broke for llvm 23 on MacOS or Windows.

anutosh491 · 2026-08-29T15:55:59Z

I think llvm 23 supports last value printing through clang-repl !

Maybe we should take care of last value printing being supported through cppinterop here ? (so that xeus-cpp can make use of it ?)

What say @Vipul-Cariappa ?

Silence diagnostic *output* by swapping in a discarding consumer rather than setting SuppressAllDiagnostics. Suppression returns from DiagnosticsEngine::ProcessDiag before ErrorOccurred/UnrecoverableErrorOccurred are set, and both CodeGen (ModuleBuilder's HandleTopLevelDecl) and IncrementalParser gate on those flags: with suppression on, an ill-formed input is handed to IRGen anyway, which crashes on the placeholder types Sema leaves in recovery ASTs (e.g. a '<dependent type>' RecoveryExpr from `*p = new Unknown{};`), and the failed PTU is never cleaned up. Replacing the client keeps the error accounting intact while printing nothing. The new client-swap keeps the error accounting honest, CleanUpPTU runs and CleanUpPTU erases the whole lookup entry for a namespace the failed input re-opened (llvm/llvm-project#201844), because re-opening replaces the predecessor in the enclosing lookup list. Every earlier declaration of that namespace goes out of reach and the next re-opening quietly starts a fresh one.

mcbarton · 2026-09-02T14:39:40Z

@Vipul-Cariappa you didn't update the deployment ci to llvm 23. When you do that update the xeus-cpp branch to cppinterop-v2.0 like Vassil did to the Emscripten ci. That way CppInterOp will have a llvm 23 deployment when this PR goes in.

Vipul-Cariappa requested review from aaronj0 and vgvassilev August 28, 2026 10:07

github-actions Bot reviewed Aug 28, 2026

View reviewed changes

mcbarton reviewed Aug 28, 2026

View reviewed changes

Vipul-Cariappa added 3 commits September 2, 2026 12:38

Support LLVM 23

bbff1c6

Update CI and README.md for LLVM 23

09fb8c8

Vipul-Cariappa force-pushed the dev/llvm23 branch from fbb2e60 to 09fb8c8 Compare September 2, 2026 10:13

	#include "llvm/ADT/SmallVector.h"
	#include "llvm/ADT/SmallVector.h"

		@@ -96,14 +96,14 @@ include(GNUInstallDirs)
		## Define supported version of clang and llvm

		set(CLANG_MIN_SUPPORTED 20.0)

		@@ -50,6 +50,7 @@ jobs:
		# Ubuntu Arm
		- { name: ubu24-arm-gcc12-llvm22-vg, os: ubuntu-24.04-arm, compiler: gcc-12, clang-runtime: '22', Valgrind: On }

		- { name: ubu24-x86-clang22-llvm22-asan-ubsan, os: ubuntu-24.04, compiler: clang-22, clang-runtime: '22', sanitizer: "Address;Undefined", flavor: asan }
		- { name: ubu24-x86-clang22-llvm22-msan, os: ubuntu-24.04, compiler: clang-22, clang-runtime: '22', sanitizer: "Memory", flavor: msan }

Uh oh!

Conversation

Vipul-Cariappa commented Aug 28, 2026

Uh oh!

codecov Bot commented Aug 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

github-actions Bot left a comment

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

github-actions Bot Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

mcbarton Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

mcbarton Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

mcbarton Aug 28, 2026

Choose a reason for hiding this comment

Uh oh!

mcbarton left a comment

Choose a reason for hiding this comment

Uh oh!

mcbarton commented Aug 28, 2026

Uh oh!

anutosh491 commented Aug 29, 2026

Uh oh!

mcbarton commented Sep 2, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

codecov Bot commented Aug 28, 2026 •

edited

Loading