[ADT] Fix MSVC build after iterator C++20 fix#173495
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@llvm/pr-subscribers-llvm-adt Author: Jorn Tuyls (jtuyls) ChangesFixes an MSCV build issue after the C++20 fix in #169772. See the failure log 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 Full diff: https://github.com/llvm/llvm-project/pull/173495.diff 1 Files Affected:
diff --git a/llvm/include/llvm/ADT/iterator.h b/llvm/include/llvm/ADT/iterator.h
index c0495e24893fb..7444409508b53 100644
--- a/llvm/include/llvm/ADT/iterator.h
+++ b/llvm/include/llvm/ADT/iterator.h
@@ -85,7 +85,9 @@ class iterator_facade_base {
using pointer = PointerT;
using reference = ReferenceT;
-protected:
+ // Note: These were previously protected, but MSVC has trouble with SFINAE
+ // accessing protected members in derived class templates (specifically in
+ // iterator_adaptor_base::operator-). Making them public fixes the build.
enum {
IsRandomAccess = std::is_base_of<std::random_access_iterator_tag,
IteratorCategoryT>::value,
@@ -93,6 +95,8 @@ class iterator_facade_base {
IteratorCategoryT>::value,
};
+protected:
+
/// A proxy object for computing a reference via indirecting a copy of an
/// iterator. This is used in APIs which need to produce a reference via
/// indirection but for which the iterator object might be a temporary. The
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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Cc some of the participants in #169772: @vedranmiletic, @kuhar, @cor3ntin, @jwakely. Could you help review? |
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Can you post the failure log here? It is not accessible without authentication. |
kuhar
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Dec 24, 2025
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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>
Contributor
Author
That also works, but we need the forward declaration of Here is the diff for the friend solution: Also, here is a snippet of the failure log btw: |
Contributor
It is a bit weird, but OTOH making them public is an API promise, which might be harder to change in the future. I would say the comment explains the weirdness of MSVC and would actually lean towards that solution. |
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ADT is not considered stable API |
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Right, then making the symbols public is fine and definitely simpler. Sorry, I don't have GitHub access to formally approve. |
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Author
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If ok, could someone help merge this? @kuhar @vedranmiletic |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/35595 Here is the relevant piece of the build log for the reference |
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Dec 29, 2025
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>
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Jan 6, 2026
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
keshavvinayak01
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Jan 27, 2026
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>
keshavvinayak01
pushed a commit
to iree-org/iree
that referenced
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Jan 27, 2026
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>
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Fixes an MSCV build issue after the C++20 fix in #169772. See the failure log 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