[jakub-labenski]

…TAD []

Discussion #336

compare_expressions checked, under CC_EXACT_EQUIVALENCE, that both nodes either have or lack rescan info. That check only ran when the type comparison was done, and the type comparison is skipped for variable references.

As a result, a specialization such as P<b> (b a dependent static data member) created by a member declaration, with no rescan info, could be reused for the same specialization in a constructor parameter type. Then, building the implicit deduction guide for class template argument deduction failed with the internal error "missing default rescan info".

Move the rescan info check out of the type comparison block so it applies to all equivalent nodes.

Add regression test
regressions/ctad-dependent-member-template-arg-reuse.sft.cpp and a Changes entry.

Summary by CodeRabbit

• Bug Fixes
  • Improved exact-equivalence checks so expression comparisons consistently account for rescan information, including when type comparison is skipped.
  • Fixed a compiler error affecting certain C++17 class template argument deduction cases involving dependent member-template arguments reused within a class. These cases can now be compiled without the previous internal error.

[coderabbitai]

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Recent review info

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• Run ID: 76a7935f-9d57-4d8c-a010-b70d3c46b919

Commits

Reviewing files that changed from the base of the PR and between 35b7c47 and e560a91.

Files selected for processing: 4

• src/il.c
• src/pending_changes/ctad-missing-rescan-info.txt
• tests/tests/regressions/.ctad-dependent-member-template-arg-reuse.rto/default.1.1.txt
• tests/tests/regressions/ctad-dependent-member-template-arg-reuse.sft.cpp

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Walkthrough

The exact-equivalence check for mismatched rescan information now also runs when type comparison is skipped. A C++17 regression test covers class template argument deduction with reused dependent member template arguments.

Changes: CTAD rescan-info handling

Layer / File(s)	Summary
Equivalence check and CTAD regression src/il.c, tests/tests/regressions/ctad-dependent-member-template-arg-reuse.sft.cpp, tests/tests/regressions/.ctad-dependent-member-template-arg-reuse.rto/default.1.1.txt, src/pending_changes/ctad-missing-rescan-info.txt	compare_expressions now checks mismatched rescan_info presence even when type comparison is skipped. The C++17 regression test exercises CTAD for two class templates, and the test invocation and change note describe the case.

Priority: Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: nv-cmeerw

Merge Risk: Minimal · up to e560a

The change addresses the reported CTAD failure, and no actionable merge-blocking risk is identified. It is ready for normal merge checks.

Pre-merge checks: 4 · 1

Failed checks: 1 inconclusive

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files. (3 skipped: 2 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly describes the main template-related fix: preventing reuse of a specialization without rescan information. It is specific and aligned with the implementation and regression test.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files. (3 skipped: 2 unsupported, 1 too large.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches

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[edgcpp-bot]

AcknowlEDG review results updated for e560a91f4de1:

• Test - Changes (new)

[edgcpp-bot]

AcknowlEDG review results updated for e560a91f4de1:

• Bench - C (new)
• Bench - C++ (new)
• Test - Changes (unchanged)

CI success.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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