[gwllx]

Fixes #532.

make_operand_for_rescanned_identifier substituted its arguments and then passed the already substituted list to scan_identifier, which substituted them again. This could lead to errors and in the #532 reproducer, a segfault. This fix avoids substituting the explicit template arguments of a dependent member template-id twice.

Summary by CodeRabbit

• Bug Fixes
  • Fixed a compiler crash when C++20 class template argument deduction uses an alias template and a constructor’s noexcept specification calls a member function template with the constructor’s parameter pack.
• Tests
  • Added regression coverage for this scenario across multiple compiler configurations.

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The compiler now stores a separately rebuilt template argument list for dependent template references, leaving the explicit list available for later substitution by scan_identifier. A C++20 regression case and compiler-specific fixtures cover alias-template CTAD with a constructor noexcept member-template call.

Changes: GH-532 regression fix

Layer / File(s)	Summary
Template argument substitution src/expr.c	The dependent template reference now uses a separately rebuilt argument list. The original explicit list remains available for substitution by scan_identifier.
Alias-template CTAD regression tests/tests/regressions/gh-532.sft.cpp, tests/tests/regressions/.gh-532.rto/*, src/pending_changes/gh-532-alias-ctad-noexcept-template-call.txt	The C++20 regression test and compiler-specific fixtures cover the reported alias-template CTAD scenario. The pending-changes note includes its description and reproducer.

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

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: nv-cmeerw, daveedvdv-nvidia

Merge Risk: Minimal · up to b8076

This change fixes a compiler crash by avoiding duplicate template argument substitution, and a regression test covers the reported case. No outstanding risks were identified, so it looks ready to merge.

Pre-merge checks: 4

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title names the crash fix, the affected feature (alias template CTAD), the triggering construct (member template call in constructor noexcept), and the issue number. The raw summary describes a ch…
Linked Issues check		Issue #532 requires that the alias-template CTAD reproducer compile under cpfe --c++20 without a segfault. The issue attributes the crash to double substitution of the explicit template arguments of…
Out of Scope Changes check		All changed files relate to #532. src/expr.c contains the substitution fix. src/pending_changes/gh-532-alias-ctad-noexcept-template-call.txt documents the fix. tests/tests/regressions/gh-532.sft.cpp a…

Full details: Title check

Explanation

The title names the crash fix, the affected feature (alias template CTAD), the triggering construct (member template call in constructor noexcept), and the issue number. The raw summary describes a change to src/expr.c that stops explicit template arguments from being substituted twice, which matches the crash fix in the title. The PR objectives describe the same duplicate-substitution bug and link it to issue #532. The title is specific and accurate, so it passes.

Full details: Linked Issues check

Explanation

Issue #532 requires that the alias-template CTAD reproducer compile under cpfe --c++20 without a segfault. The issue attributes the crash to double substitution of the explicit template arguments of a dependent member template-id, which leads to an out-of-range index in get_template_arg_by_list_pos. The diff in src/expr.c (whole PR, merge base to head) changes the dependent non-type template parameter branch of make_operand_for_rescanned_identifier. The expression copy_template_arg_list_with_substitution_rebuilding_arg_operands now writes its result to a new local, subst_templ_arg_list. The unsubstituted expl_templ_arg_list is no longer replaced, so scan_identifier performs the only substitution. The template-reference constant's arg_list takes the rebuilt list. This addresses the root cause that #532 describes. The PR also adds a regression test, tests/tests/regressions/gh-532.sft.cpp, with the reproducer and matching .rto fixtures. I did not execute the compiler, so the absence of the segfault rests on source reading and the added test, not on a run result.

Full details: Out of Scope Changes check

Explanation

All changed files relate to #532. src/expr.c contains the substitution fix. src/pending_changes/gh-532-alias-ctad-noexcept-template-call.txt documents the fix. tests/tests/regressions/gh-532.sft.cpp and the .rto/default.N.1.txt fixtures add the regression test and its command variants. The src/expr.c hunk is limited to the affected branch and its comment. No unrelated behavior change appears in the reviewed hunk. The whole-PR diff of other source files was not inspected in full, but the change summary lists no other source changes.

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Recent review info

Run configuration

• Source mode: Auto
• Repository: edgcpp/compiler
• Branch: main
• File: .coderabbit.yaml
• Commit: cd21a3e
• Layers: Repository YAML
• Review profile: CHILL
• Plan: Advanced
• Run ID: 7dcc65ca-5770-4e2d-87c8-f0b9f32d3a89

Commits

Reviewing files that changed from the base of the PR and between ed0db74 and b8076ed.

Files selected for processing: 7

• src/expr.c
• src/pending_changes/gh-532-alias-ctad-noexcept-template-call.txt
• tests/tests/regressions/.gh-532.rto/default.1.1.txt
• tests/tests/regressions/.gh-532.rto/default.2.1.txt
• tests/tests/regressions/.gh-532.rto/default.3.1.txt
• tests/tests/regressions/.gh-532.rto/default.4.1.txt
• tests/tests/regressions/gh-532.sft.cpp

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 2 remain after this review.

[nv-cmeerw]

Thanks. Just a few minor comments; and please change the GH references to the issue #532

[edgcpp-bot]

AcknowlEDG review results updated for ed0db74daa3b:

• Test - Changes (new)

[edgcpp-bot]

AcknowlEDG review results updated for ed0db74daa3b:

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

CI success.

[nv-cmeerw]

Thanks, looks good to me.

[edgcpp-bot]

AcknowlEDG review results updated for b8076ed3a6e7:

• Bench - C (updated)
• Bench - C++ (updated)
• Test - Changes (updated)

CI success.