CU-2083 Update scip-clang to newer Clang version #508

chrapkowski-sg · 2025-12-30T16:26:35Z

Update scip-clang to newer Clang 21 version

chrapkowski-sg · 2025-12-30T16:26:36Z

This change is part of the following stack:

CU-2083 Update scip-clang to newer Clang version #508 ◀

_{Change managed by git-spice.}

indexer/Indexer.cc

chrapkowski-sg · 2025-12-30T17:35:57Z

indexer/ApproximateNameResolver.cc

+        llvm::dyn_cast<clang::CXXRecordDecl>(baseType->getDecl());
+    if (!baseRecord || !baseRecord->hasDefinition())
+      continue;
+    auto baseResults =


CXXRecordDecl::lookupDependentName() was removed from the Clang API in LLVM 21. This is a local reimplementation with the same semantics.

Looked up the reason why it was removed: llvm/llvm-project#128392. It seems there is a newer API that should be used instead (HeuristicResolver).

chrapkowski-sg · 2025-12-30T17:35:57Z

indexer/Indexer.cc

  auto symbol = optSymbol.value();

-  if (functionDecl.isPure() || functionDecl.isThisDeclarationADefinition()) {
+  if (functionDecl.isPureVirtual() || functionDecl.isThisDeclarationADefinition()) {


isPure() was renamed to isPureVirtual() in LLVM 21 for clarity.

chrapkowski-sg · 2025-12-30T17:35:57Z

indexer/Indexer.h

  }
  DERIVE_CMP_ALL(FileLocalSourceRange)
-  DERIVE_EQ_ALL(FileLocalSourceRange)



DERIVE_CMP_ALL now generates operator== via C++20 operator<=>, making DERIVE_EQ_ALL redundant and causing a compile error.

indexer/Path.cc

indexer/Preprocessing.h

chrapkowski-sg · 2025-12-30T17:35:57Z

third_party/llvm-cuda-tooling.patch

@@ -0,0 +1,29 @@
+diff --git a/clang/lib/Tooling/Tooling.cpp b/clang/lib/Tooling/Tooling.cpp


Cherry-pick fix for CUDA assertion failure from llvm/llvm-project#173762. Can be removed once LLVM merges the fix.

chrapkowski-sg · 2025-12-30T17:35:57Z

setup_llvm.bzl

+    # LLVM 21 uses new naming convention: LLVM-VERSION-Platform.tar.xz
+    # with strip prefix LLVM-VERSION-Platform
    grailbio_llvm_toolchain(
        name = name,


LLVM 21 changed release archive naming from clang+llvm-VERSION-TRIPLE to LLVM-VERSION-Platform.

chrapkowski-sg · 2025-12-30T17:37:02Z

indexer/JsonIpcQueue.h

 #include "boost/interprocess/ipc/message_queue.hpp"
 #pragma clang diagnostic pop

-#include "llvm/ADT/Optional.h"


llvm::Optional was removed in favor of std::optional. This include is no longer needed.

test/index/types/inheritance.snapshot.cc

chrapkowski-sg · 2025-12-31T12:01:45Z

test/index/cuda/kernelcall.snapshot.cu

@@ -52,7 +52,6 @@
 //  ^^ reference local 5

    g1<<<undeclared, 1>>>(42); // expected-error {{use of undeclared identifier 'undeclared'}}


In the line g1<<<undeclared, 1>>>(42);, when the kernel configuration contains an undeclared identifier (undeclared), Clang 21 no longer generates a DeclRefExpr for the callee function g1

chrapkowski-sg · 2026-01-02T00:36:22Z

.bazelrc

 common --enable_platform_specific_config

+# Disable bzlmod for now - WORKSPACE dependencies not yet migrated
+common --enable_bzlmod=false


Update to bazel 7 but we still use WORKSPACE not modules

chrapkowski-sg · 2026-01-02T00:38:35Z

.bazelrc

-# Based on release notes from since we're on Bazel < 7
-# https://github.com/bazel-contrib/toolchains_llvm/releases/tag/0.10.3
-build --features=-supports_dynamic_linker
-build --features=-libtool


We use bazel 7+ so no longer needed

chrapkowski-sg · 2026-01-02T00:38:47Z

.bazelrc

 build --incompatible_enable_cc_toolchain_resolution

-build --repo_env BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1 
-build --@llvm_zstd//:llvm_enable_zstd=false


We use bazel 7+ so no longer needed

chrapkowski-sg · 2026-01-12T11:21:19Z

The Release workflow triggered for this PR failed. This must be fixed before the PR can be merged. That said, the error doesn't seem to be caused by the code changes ("No space left on device," and I was able to build scip-clang manually on both Linux and macOS).

While not a hard requirement right now, in the future it would be nice to split such PRs into separate scopes (in this case, I imagine something like a Bazel update and a Clang update).

Overall, this looks good to me. Once we have the Release pipeline working, this should be easy to merge.

https://github.com/sourcegraph/scip-clang/actions/runs/20861193543

.buildkite/pipeline.yaml

jupblb

Please fix //tools:compdb and replace tryFindDeclForBaseType with HeuristicResolver.

.buildkite/pipeline.yaml

jupblb · 2026-01-16T11:54:47Z

.aspect/workflows/config.yaml

+  - build:
+      targets:
+          - //...
+          - -//tools:compdb  # Exclude: com_grail_bazel_compdb is incompatible with current toolchain


It seems to me that //tools:compdb is overall broken by this PR. This must be addressed as compile_commands.json is needed for local development (and C++ SCIP index generation). If there is an alternative way to generate this file that's also fine.

Yes, you are right of course.

I replaced:

load("@com_grail_bazel_compdb//:defs.bzl", "compilation_database")

with

load("@hedron_compile_commands//:refresh_compile_commands.bzl", "refresh_compile_commands")

Since compdb is unmaintained https://github.com/grailbio/bazel-compilation-database "This repository was archived by the owner on Mar 17, 2024. It is now read-only. "

jupblb · 2026-01-16T12:02:48Z

indexer/ApproximateNameResolver.cc

+        llvm::dyn_cast<clang::CXXRecordDecl>(baseType->getDecl());
+    if (!baseRecord || !baseRecord->hasDefinition())
+      continue;
+    auto baseResults =


Looked up the reason why it was removed: llvm/llvm-project#128392. It seems there is a newer API that should be used instead (HeuristicResolver).

jupblb · 2026-01-16T13:38:05Z

tools/reformat.sh

+if bazel-bin/external/llvm_toolchain/clang-format --version >/dev/null 2>&1; then
+  CLANG_FORMAT="bazel-bin/external/llvm_toolchain/clang-format"
+elif command -v clang-format >/dev/null 2>&1; then
+  echo "Warning: Using system clang-format (LLVM toolchain version not compatible with this system)"


Is this still an issue on newer OS like macOS Tahoe or Ubuntu 24.04? If not, I'd revert these changes.

jupblb · 2026-01-16T13:42:22Z

fetch_deps.bzl

-        strip_prefix = "abseil-cpp-%s" % _ABSL_COMMIT,
-        urls = ["https://github.com/abseil/abseil-cpp/archive/%s.zip" % _ABSL_COMMIT],
-        patch_args = ["-p1"],
-        patches = ["//third_party:abseil.patch"],


File with this patch can be removed.

jupblb · 2026-01-16T13:44:07Z

setup_llvm.bzl

+        # On Linux, use the bundled libc++ (builtin-libc++) for hermetic builds.
+        stdlib = {
+            "darwin-aarch64": "libc++",
+            "darwin-x86_64": "libc++",


We should drop support for darwin-x86_64 (can be done in another PR).

jupblb · 2026-01-16T13:59:05Z

setup_llvm.bzl


+# macOS SDK path for system libc++ headers
+# This is the standard location for Xcode Command Line Tools SDK
+_MACOS_SDK = "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk"


Please add a comment that this variable should be set to xcrun --show-sdk-path output.

chrapkowski-sg · 2026-01-21T13:23:35Z

docs/Development.md

 ## IDE integration

-Run `./tools/regenerate-compdb.sh` to generate a compilation database
+Run `./tools/regenerate-compile-commands.sh` to generate a compilation database


Since compdb has been removed, I renamed this tool to avoid confusion and coupling with underlaying tool name

chrapkowski-sg · 2026-01-21T13:29:32Z

tools/translation_unit_runner.py

            self.arguments = shlex.split(entry["command"])
        except KeyError:
-            self.arguments = entry(["arguments"])
+            self.arguments = entry["arguments"]


Bugfix in error handling

…commands_setup

jupblb · 2026-01-23T12:58:21Z

tools/regenerate-compdb.sh

+# The --features flags disable module_maps which is incompatible with the
+# grailbio/bazel-compilation-database library (archived, no longer maintained).
+# See: https://github.com/grailbio/bazel-compilation-database/issues/101
+bazel build //tools:compdb --features=-layering_check --features=-module_maps


It doesn't seem to me that we use com_grail_bazel_compdb anymore? What is the consequence of disabling module_maps and layering_check?

Oh, noticed #508 (comment)

chrapkowski-sg commented Dec 30, 2025

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burmudar and others added 4 commits January 9, 2026 16:42

split step into lint and build and use diff agents

b30df85

define aspect config for aspect workflows

0cd29ff

Disabled bzmod for aspect

ee67b51

Re-introduced reformat

d4761e4

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Updated release action

2d95b5c

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Applied review comments

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chrapkowski-sg commented Jan 14, 2026

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chrapkowski-sg requested a review from jupblb January 14, 2026 16:41

jupblb requested changes Jan 16, 2026

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jupblb reviewed Jan 16, 2026

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Renamed compdb.py to avoid expressing relationship to compdb library

6cc3cf1

chrapkowski-sg commented Jan 21, 2026

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chrapkowski-sg commented Jan 21, 2026

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Replaced bazel_compdb_deps which is unmaintained with hedron_compile_…

9636366

…commands_setup

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jupblb reviewed Jan 23, 2026

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		@@ -0,0 +1,29 @@
		diff --git a/clang/lib/Tooling/Tooling.cpp b/clang/lib/Tooling/Tooling.cpp

		@@ -52,7 +52,6 @@
		// ^^ reference local 5

		g1<<<undeclared, 1>>>(42); // expected-error {{use of undeclared identifier 'undeclared'}}

CU-2083 Update scip-clang to newer Clang version #508

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CU-2083 Update scip-clang to newer Clang version #508

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chrapkowski-sg commented Jan 12, 2026

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chrapkowski-sg commented Dec 30, 2025 •

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