https://github.com/Lambo-IITian created https://github.com/llvm/llvm-project/pull/180175
### Description Fixes #180046 This PR addresses issue #180046 where Clang elides the wrong part of template types in error messages, specifically hiding important type qualifiers (like `const` or `volatile`) behind `[...]`. The fix ensures that when template types differ only by qualifiers, those qualifiers are preserved in the diagnostic output rather than being elided, making the error messages much more actionable. ## Before changes error <img width="1740" height="267" alt="Screenshot 2026-02-06 172130" src="https://github.com/user-attachments/assets/ef3d2d99-d2b1-4cde-8017-b41142004069"; /> ## After changes error <img width="919" height="348" alt="Screenshot 2026-02-06 172337" src="https://github.com/user-attachments/assets/c458b47b-ef8a-4d07-84fa-677cce4be271"; /> >From 31e6ffdd6275caacb8c03a890c607377c5b66dbe Mon Sep 17 00:00:00 2001 From: Mohit Gunani <[email protected]> Date: Fri, 6 Feb 2026 17:10:56 +0530 Subject: [PATCH] [Clang] Improve template diffing to show qualifiers in elided types This change ensures that template diagnostics like Dual<int, [...]> vs Dual<const int, [...]> correctly display the differing qualifiers instead of hiding the entire type. --- clang/lib/AST/ASTDiagnostic.cpp | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/clang/lib/AST/ASTDiagnostic.cpp b/clang/lib/AST/ASTDiagnostic.cpp index b8023cb6fa10f..44983edbf870a 100644 --- a/clang/lib/AST/ASTDiagnostic.cpp +++ b/clang/lib/AST/ASTDiagnostic.cpp @@ -1205,8 +1205,16 @@ class TemplateDiff { "Both template specializations need to be valid."); Qualifiers FromQual = FromType.getQualifiers(), ToQual = ToType.getQualifiers(); - FromQual -= QualType(FromArgTST, 0).getQualifiers(); - ToQual -= QualType(ToArgTST, 0).getQualifiers(); + // FromQual -= QualType(FromArgTST, 0).getQualifiers(); + // ToQual -= QualType(ToArgTST, 0).getQualifiers(); + // ... your commented out lines ... + bool Same = false; + if (FromArgTST->getTemplateName().getAsTemplateDecl() == + ToArgTST->getTemplateName().getAsTemplateDecl()) { + // If the names match, the ONLY thing that makes them different is the Qualifiers + Same = (FromQual == ToQual); + } + Tree.SetSame(Same); Tree.SetTemplateDiff(FromArgTST->getTemplateName().getAsTemplateDecl(), ToArgTST->getTemplateName().getAsTemplateDecl(), FromQual, ToQual, FromDefault, ToDefault); _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
