Fixed build with C++20 standard by vedranmiletic · Pull Request #169772 · llvm/llvm-project

vedranmiletic · 2025-11-27T08:03:57Z

Building LLVM with CMAKE_CXX_STANDARD set to 20 fails since the iterator facade is not fully compatible with C++20. To make it compatible, specific operator overloads have to be constrained.

Overload for operator- in ADT iterator is now constrained with concept BaseT::IsRandomAccess.

Patch by Jonathan Wakely.

Fixes #139072.

Overload for operator- in ADT iterator is now constrained with concept BaseT::IsRandomAccess. Patch by Jonathan Wakely. Fixes llvm#139072.

llvmbot · 2025-11-27T08:05:00Z

@llvm/pr-subscribers-llvm-adt

Author: Vedran Miletić (vedranmiletic)

Changes

Overload for operator- in ADT iterator is now constrained with concept BaseT::IsRandomAccess.

Patch by Jonathan Wakely.

Fixes #139072.

Full diff: https://github.com/llvm/llvm-project/pull/169772.diff

1 Files Affected:

(modified) llvm/include/llvm/ADT/iterator.h (+5-1)

diff --git a/llvm/include/llvm/ADT/iterator.h b/llvm/include/llvm/ADT/iterator.h
index 6f0c42fe08bec..f55f9d4a3e7f2 100644
--- a/llvm/include/llvm/ADT/iterator.h
+++ b/llvm/include/llvm/ADT/iterator.h
@@ -267,7 +267,11 @@ class iterator_adaptor_base
     return *static_cast<DerivedT *>(this);
   }
   using BaseT::operator-;
-  difference_type operator-(const DerivedT &RHS) const {
+  difference_type operator-(const DerivedT &RHS) const
+#ifdef __cpp_concepts
+    requires(bool(BaseT::IsRandomAccess))
+#endif
+  {
     static_assert(
         BaseT::IsRandomAccess,
         "The '-' operator is only defined for random access iterators.");

jwakely

As noted at #139072 (comment) there are other operators which should really be constrained similarly. So this fixes the immediate issue, but there are still latent bugs that might cause similar errors later.

jwakely · 2025-11-27T09:57:27Z

but there are still latent bugs that might cause similar errors later.

But they could be fixed later, if needed.

llvm/include/llvm/ADT/iterator.h

cor3ntin · 2025-11-27T12:33:33Z

Please update the description of the PR with a description of the problem you are trying to fix, I had to find this comment to understand the context. Thanks
#139072 (comment)

Co-authored-by: A. Jiang <de34@live.cn>

github-actions · 2025-11-27T19:57:56Z

✅ With the latest revision this PR passed the C/C++ code formatter.

vedranmiletic · 2025-11-28T15:11:19Z

Please update the description of the PR with a description of the problem you are trying to fix, I had to find this comment to understand the context. Thanks #139072 (comment)

Hope it is better now.

llvm/include/llvm/ADT/iterator.h

Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>

vedranmiletic · 2025-12-23T10:48:54Z

Can someone merge this for me? I don't have commit access.

llvm-ci · 2025-12-23T19:46:10Z

LLVM Buildbot has detected a new failure on builder ppc64le-mlir-rhel-clang running on ppc64le-mlir-rhel-test while building llvm at step 6 "test-build-check-mlir-build-only-check-mlir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/35481

Here is the relevant piece of the build log for the reference

Step 6 (test-build-check-mlir-build-only-check-mlir) failure: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
...
PASS: MLIR-Unit :: Dialect/SparseTensor/./MLIRSparseTensorTests/95/210 (3773 of 3784)
PASS: MLIR-Unit :: Dialect/SparseTensor/./MLIRSparseTensorTests/97/210 (3774 of 3784)
PASS: MLIR-Unit :: IR/./MLIRIRTests/0/131 (3775 of 3784)
PASS: MLIR-Unit :: IR/./MLIRIRTests/39/131 (3776 of 3784)
PASS: MLIR-Unit :: IR/./MLIRIRTests/38/131 (3777 of 3784)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/11/22 (3778 of 3784)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/12/22 (3779 of 3784)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/13/22 (3780 of 3784)
PASS: MLIR-Unit :: Pass/./MLIRPassTests/11/14 (3781 of 3784)
PASS: MLIR :: mlir-reduce/dce-test.mlir (3782 of 3784)
command timed out: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=4205.691615

vedranmiletic · 2025-12-24T14:22:01Z

Thanks!

Building LLVM with CMAKE_CXX_STANDARD set to 20 fails since the iterator facade is not fully compatible with C++20. To make it compatible, specific operator overloads have to be constrained. Overload for operator- in ADT iterator is now constrained with concept BaseT::IsRandomAccess. Patch by Jonathan Wakely. Fixes llvm#139072. --------- Co-authored-by: A. Jiang <de34@live.cn> Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>

This reverts commit a666d1f.

Integrate llvm/llvm-project@c0f4a8a Existing local reverts carried forward: * Local revert of llvm/llvm-project#169614 due to llvm/llvm-project#172932. Also adds a revert for a commit that breaks the MSVC build: * Local revert of llvm/llvm-project#169772. This can be dropped after llvm/llvm-project#173495. Signed-off-by: Jorn Tuyls <jorn.tuyls@gmail.com>

Fixes an MSCV build issue after the C++20 fix in #169772. See the [failure log](https://productionresultssa1.blob.core.windows.net/actions-results/604d315e-edbd-401f-9a85-9ec5fcbc4996/workflow-job-run-99b94847-47a4-5b95-9933-44db3e32a2a7/logs/job/job-logs.txt?rsct=text%2Fplain&se=2025-12-24T11%3A16%3A19Z&sig=3leOtxGMlJmAMzOCtakzD8%2FOQCXF2HfflooR%2Bm%2Bt7Ng%3D&ske=2025-12-24T21%3A53%3A06Z&skoid=ca7593d4-ee42-46cd-af88-8b886a2f84eb&sks=b&skt=2025-12-24T09%3A53%3A06Z&sktid=398a6654-997b-47e9-b12b-9515b896b4de&skv=2025-11-05&sp=r&spr=https&sr=b&st=2025-12-24T11%3A06%3A14Z&sv=2025-11-05) in the IREE downstream project. Making IsRandomAccess, IsBidirectional public ensures that they are always accessible, avoiding the access-related SFINAE ambiguity that causes different compilers to handle this differently. The build is passing after this change: https://github.com/iree-org/iree/actions/runs/20485132054/job/58865989220?pr=22979

Fixes an MSCV build issue after the C++20 fix in llvm/llvm-project#169772. See the [failure log](https://productionresultssa1.blob.core.windows.net/actions-results/604d315e-edbd-401f-9a85-9ec5fcbc4996/workflow-job-run-99b94847-47a4-5b95-9933-44db3e32a2a7/logs/job/job-logs.txt?rsct=text%2Fplain&se=2025-12-24T11%3A16%3A19Z&sig=3leOtxGMlJmAMzOCtakzD8%2FOQCXF2HfflooR%2Bm%2Bt7Ng%3D&ske=2025-12-24T21%3A53%3A06Z&skoid=ca7593d4-ee42-46cd-af88-8b886a2f84eb&sks=b&skt=2025-12-24T09%3A53%3A06Z&sktid=398a6654-997b-47e9-b12b-9515b896b4de&skv=2025-11-05&sp=r&spr=https&sr=b&st=2025-12-24T11%3A06%3A14Z&sv=2025-11-05) in the IREE downstream project. Making IsRandomAccess, IsBidirectional public ensures that they are always accessible, avoiding the access-related SFINAE ambiguity that causes different compilers to handle this differently. The build is passing after this change: https://github.com/iree-org/iree/actions/runs/20485132054/job/58865989220?pr=22979

Integrate llvm/llvm-project@75a0347 Removes a revert: * Local revert of llvm/llvm-project#169772 as the fix in llvm/llvm-project#173495 got merged. Existing local reverts carried forward: * Local revert of llvm/llvm-project#169614 due to llvm/llvm-project#172932. Signed-off-by: Jorn Tuyls <jorn.tuyls@gmail.com>

Building LLVM with CMAKE_CXX_STANDARD set to 20 fails since the iterator facade is not fully compatible with C++20. To make it compatible, specific operator overloads have to be constrained. Overload for operator- in ADT iterator is now constrained with concept BaseT::IsRandomAccess. Patch by Jonathan Wakely. Fixes llvm#139072. --------- Co-authored-by: A. Jiang <de34@live.cn> Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>

Fixes an MSCV build issue after the C++20 fix in llvm#169772. See the [failure log](https://productionresultssa1.blob.core.windows.net/actions-results/604d315e-edbd-401f-9a85-9ec5fcbc4996/workflow-job-run-99b94847-47a4-5b95-9933-44db3e32a2a7/logs/job/job-logs.txt?rsct=text%2Fplain&se=2025-12-24T11%3A16%3A19Z&sig=3leOtxGMlJmAMzOCtakzD8%2FOQCXF2HfflooR%2Bm%2Bt7Ng%3D&ske=2025-12-24T21%3A53%3A06Z&skoid=ca7593d4-ee42-46cd-af88-8b886a2f84eb&sks=b&skt=2025-12-24T09%3A53%3A06Z&sktid=398a6654-997b-47e9-b12b-9515b896b4de&skv=2025-11-05&sp=r&spr=https&sr=b&st=2025-12-24T11%3A06%3A14Z&sv=2025-11-05) in the IREE downstream project. Making IsRandomAccess, IsBidirectional public ensures that they are always accessible, avoiding the access-related SFINAE ambiguity that causes different compilers to handle this differently. The build is passing after this change: https://github.com/iree-org/iree/actions/runs/20485132054/job/58865989220?pr=22979

Fixes an MSCV build issue after the C++20 fix in llvm/llvm-project#169772. See the [failure log](https://productionresultssa1.blob.core.windows.net/actions-results/604d315e-edbd-401f-9a85-9ec5fcbc4996/workflow-job-run-99b94847-47a4-5b95-9933-44db3e32a2a7/logs/job/job-logs.txt?rsct=text%2Fplain&se=2025-12-24T11%3A16%3A19Z&sig=3leOtxGMlJmAMzOCtakzD8%2FOQCXF2HfflooR%2Bm%2Bt7Ng%3D&ske=2025-12-24T21%3A53%3A06Z&skoid=ca7593d4-ee42-46cd-af88-8b886a2f84eb&sks=b&skt=2025-12-24T09%3A53%3A06Z&sktid=398a6654-997b-47e9-b12b-9515b896b4de&skv=2025-11-05&sp=r&spr=https&sr=b&st=2025-12-24T11%3A06%3A14Z&sv=2025-11-05) in the IREE downstream project. Making IsRandomAccess, IsBidirectional public ensures that they are always accessible, avoiding the access-related SFINAE ambiguity that causes different compilers to handle this differently. The build is passing after this change: https://github.com/iree-org/iree/actions/runs/20485132054/job/58865989220?pr=22979

Fixes an MSCV build issue after the C++20 fix in llvm/llvm-project#169772. See the [failure log](https://productionresultssa1.blob.core.windows.net/actions-results/604d315e-edbd-401f-9a85-9ec5fcbc4996/workflow-job-run-99b94847-47a4-5b95-9933-44db3e32a2a7/logs/job/job-logs.txt?rsct=text%2Fplain&se=2025-12-24T11%3A16%3A19Z&sig=3leOtxGMlJmAMzOCtakzD8%2FOQCXF2HfflooR%2Bm%2Bt7Ng%3D&ske=2025-12-24T21%3A53%3A06Z&skoid=ca7593d4-ee42-46cd-af88-8b886a2f84eb&sks=b&skt=2025-12-24T09%3A53%3A06Z&sktid=398a6654-997b-47e9-b12b-9515b896b4de&skv=2025-11-05&sp=r&spr=https&sr=b&st=2025-12-24T11%3A06%3A14Z&sv=2025-11-05) in the IREE downstream project. Making IsRandomAccess, IsBidirectional public ensures that they are always accessible, avoiding the access-related SFINAE ambiguity that causes different compilers to handle this differently. The build is passing after this change: https://github.com/iree-org/iree/actions/runs/20485132054/job/58865989220?pr=22979 (cherry picked from commit 75a0347)

Integrate llvm/llvm-project@c0f4a8a Existing local reverts carried forward: * Local revert of llvm/llvm-project#169614 due to llvm/llvm-project#172932. Also adds a revert for a commit that breaks the MSVC build: * Local revert of llvm/llvm-project#169772. This can be dropped after llvm/llvm-project#173495. Signed-off-by: Jorn Tuyls <jorn.tuyls@gmail.com> Signed-off-by: Keshav Vinayak Jha <keshavvinayakjha@gmail.com>

Integrate llvm/llvm-project@75a0347 Removes a revert: * Local revert of llvm/llvm-project#169772 as the fix in llvm/llvm-project#173495 got merged. Existing local reverts carried forward: * Local revert of llvm/llvm-project#169614 due to llvm/llvm-project#172932. Signed-off-by: Jorn Tuyls <jorn.tuyls@gmail.com> Signed-off-by: Keshav Vinayak Jha <keshavvinayakjha@gmail.com>

Fixed build with C++20 standard

f3b449a

Overload for operator- in ADT iterator is now constrained with concept BaseT::IsRandomAccess. Patch by Jonathan Wakely. Fixes llvm#139072.

llvmbot added the llvm:adt label Nov 27, 2025

jwakely reviewed Nov 27, 2025

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frederick-vs-ja reviewed Nov 27, 2025

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llvm/include/llvm/ADT/iterator.h Outdated Show resolved Hide resolved

Update llvm/include/llvm/ADT/iterator.h

bda2870

Co-authored-by: A. Jiang <de34@live.cn>

Format

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kuhar reviewed Nov 30, 2025

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llvm/include/llvm/ADT/iterator.h Outdated Show resolved Hide resolved

Update llvm/include/llvm/ADT/iterator.h

807d18a

Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>

cor3ntin approved these changes Dec 1, 2025

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kuhar approved these changes Dec 1, 2025

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Merge branch 'main' into adt-iterator-cpp-20

9326a17

Merge branch 'main' into adt-iterator-cpp-20

8a27385

kuhar merged commit a666d1f into llvm:main Dec 23, 2025
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jtuyls mentioned this pull request Dec 24, 2025

[ADT] Fix MSVC build after iterator C++20 fix #173495

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Integrate LLVM at c0f4a8a iree-org/iree#22979

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Revert "Fixed build with C++20 standard (llvm#169772)"

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This reverts commit a666d1f.

jtuyls mentioned this pull request Dec 29, 2025

Integrate LLVM at 75a0347 iree-org/iree#22985

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Fixed build with C++20 standard#169772

Fixed build with C++20 standard#169772
kuhar merged 6 commits intollvm:mainfrom
vedranmiletic:adt-iterator-cpp-20

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