en Copyright 2015 Java http://172.16.0.5:8080/history/llvm-project-15.0.7/clang/test/SemaTemplate/concepts-PR54629.cpp#342e6497 [Sema] Fix assertion failure when instantiating requires expressionFixes #54629.The crash is is caused by the double template instantiation.See the added test. Here is what happens:- Template arguments for the partial specialization get instantiated.- This causes instantitation into the corrensponding requires expression.- `TemplateInsantiator` correctly handles instantiation of parameters inside `RequiresExprBody` and instantiates the constraint expression inside the `NestedRequirement`.- To build the substituted `NestedRequirement`, `TemplateInsantiator` calls `Sema::BuildNestedRequirement` calls `CheckConstraintSatisfaction`, which results in another template instantiation (with empty template arguments). This seem to be an implementation detail to handle constraint satisfaction and is not required by the standard.- The recursive template instantiation tries to find the parameter inside `RequiresExprBody` and fails with the corresponding assertion.Note that this only happens as both instantiations happen with the classpartial template specialization set as `Sema.CurContext`, which isconsidered a dependent `DeclContext`.To fix the assertion, avoid doing the recursive template instantiationand instead evaluate resulting expressions in-place.Reviewed By: erichkeaneDifferential Revision: https://reviews.llvm.org/D127487 List of files: /llvm-project-15.0.7/clang/test/SemaTemplate/concepts-PR54629.cpp Thu, 23 Jun 2022 13:52:16 +0000 Ilya Biryukov <ibiryukov@google.com>