)]}'
{
  "commit": "1cb47c19f8eca4badd8fb5e1a1b1cf4aaab607b8",
  "tree": "d93a81d4d8c5b14cc7c416039397fff7b334f8d3",
  "parents": [
    "f6e8b26eab8324a60f437fdb3e88e5d5105c9845"
  ],
  "author": {
    "name": "Andrey Ali Khan Bolshakov",
    "email": "bolsh.andrey@yandex.ru",
    "time": "Thu Sep 04 18:32:12 2025 +0300"
  },
  "committer": {
    "name": "GitHub",
    "email": "noreply@github.com",
    "time": "Thu Sep 04 15:32:12 2025 +0000"
  },
  "message": "[clang] Remove written template args from implicit var tpl spec (#156329)\n\n`VarTemplateSpecializationDecl::getTemplateArgsAsWritten()` function\nshould return `nullptr` in the case of implicit instantiation, as its\n`ClassTemplateSpecializationDecl` counterpart does, and not the\narguments written in `DeclRefExpr` referencing the specialization in the\nfirst place. Otherwise, for such code:\n```cpp\ntemplate \u003ctypename\u003e\nint VarTpl;\n\ntemplate \u003ctypename T\u003e\nvoid tplFn() {\n  (void)VarTpl\u003cT\u003e;  // (1)\n}\n\nvoid fn() {\n  tplFn\u003cchar\u003e();\n}\n```\nClang treats the `char` argument of the `VarTpl` specialization as if it\nwere written in the line marked as (1), which is misleading and hardly\nmakes sense.\n\nMoreover, \"template args as written\" are stored inside `ExplicitInfo`\nfield of `VarTemplateSpecializationDecl`, but it is\n[documented](https://github.com/llvm/llvm-project/blob/13357e8a12c1a45364a0c4d3137b6d21ee6ac40c/clang/include/clang/AST/DeclTemplate.h#L2653)\nthat it is not for implicit instantiations.\n\nMoreover, it is assumed in `TraverseVarTemplateSpecializationDecl`\nmethod of `RecursiveASTVisitor` that `getTemplateArgsAsWritten()`\nreturns `nullptr` for implicit instantiations, as it is stated in the\ncomment\n[there](https://github.com/llvm/llvm-project/blob/13357e8a12c1a45364a0c4d3137b6d21ee6ac40c/clang/include/clang/AST/RecursiveASTVisitor.h#L2196).\n\nThat said, `setTemplateArgsAsWritten` should be called only for variable\ntemplate explicit specializations (it is [already done inside\n`Sema::ActOnVarTemplateSpecialization`](https://github.com/llvm/llvm-project/blob/4c916273041ff5ed7b2af20bec787ffc42871c9f/clang/lib/Sema/SemaTemplate.cpp#L4459))\nand explicit instantiations (hence `true` is passed to the new\n`SetWrittenArgs` parameter of `CheckVarTemplateId` function inside\n`Sema::ActOnExplicitInstantiation`, but not when handling expressions\nreferencing a variable template specialization).\n`InstantiateVariableDefinition` function just passes the arguments from\nthe corresponding declaration. I\u0027m not sure about instantiating a class\ntemplate containing a variable template explicit specialization and thus\nhave tried to leave the logic of the first overload of\n`TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl` as it\nwas.",
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