llvm-project/clang/test/SemaTemplate/recovery-tree-transform.cpp

// RUN: %clang_cc1 -verify -frecovery-ast %s

template<typename T> int *p = &void(T::error); // expected-error{{cannot take the address of an rvalue}} expected-error{{type 'int' cannot be used prior to '::'}}
int *q = p<int>; // expected-note{{in instantiation of variable template specialization 'p<int>' requested here}}
[AST] Add RecoveryExpr to retain expressions on semantic errors Normally clang avoids creating expressions when it encounters semantic errors, even if the parser knows which expression to produce. This works well for the compiler. However, this is not ideal for source-level tools that have to deal with broken code, e.g. clangd is not able to provide navigation features even for names that compiler knows how to resolve. The new RecoveryExpr aims to capture the minimal set of information useful for the tools that need to deal with incorrect code: source range of the expression being dropped, subexpressions of the expression. We aim to make constructing RecoveryExprs as simple as possible to ensure writing code to avoid dropping expressions is easy. Producing RecoveryExprs can result in new code paths being taken in the frontend. In particular, clang can produce some new diagnostics now and we aim to suppress bogus ones based on Expr::containsErrors. We deliberately produce RecoveryExprs only in the parser for now to minimize the code affected by this patch. Producing RecoveryExprs in Sema potentially allows to preserve more information (e.g. type of an expression), but also results in more code being affected. E.g. SFINAE checks will have to take presence of RecoveryExprs into account. Initial implementation only works in C++ mode, as it relies on compiler postponing diagnostics on dependent expressions. C and ObjC often do not do this, so they require more work to make sure we do not produce too many bogus diagnostics on the new expressions. See documentation of RecoveryExpr for more details. original patch from Ilya This change is based on https://reviews.llvm.org/D61722 Reviewers: sammccall, rsmith Reviewed By: sammccall, rsmith Tags: #clang Differential Revision: https://reviews.llvm.org/D69330 2020-03-19 23:30:40 +08:00			`// RUN: %clang_cc1 -verify -frecovery-ast %s`

			`template<typename T> int *p = &void(T::error); // expected-error{{cannot take the address of an rvalue}} expected-error{{type 'int' cannot be used prior to '::'}}`
			`int *q = p<int>; // expected-note{{in instantiation of variable template specialization 'p<int>' requested here}}`