llvm-project/clang/test/CXX/basic/basic.lookup
Richard Smith b23c5e8c3d [c++20] Implement P0846R0: allow (ADL-only) calls to template-ids whose
template name is not visible to unqualified lookup.

In order to support this without a severe degradation in our ability to
diagnose typos in template names, this change significantly restructures
the way we handle template-id-shaped syntax for which lookup of the
template name finds nothing.

Instead of eagerly diagnosing an undeclared template name, we now form a
placeholder template-name representing a name that is known to not find
any templates. When the parser sees such a name, it attempts to
disambiguate whether we have a less-than comparison or a template-id.
Any diagnostics or typo-correction for the name are delayed until its
point of use.

The upshot should be a small improvement of our diagostic quality
overall: we now take more syntactic context into account when trying to
resolve an undeclared identifier on the left hand side of a '<'. In
fact, this works well enough that the backwards-compatible portion (for
an undeclared identifier rather than a lookup that finds functions but
no function templates) is enabled in all language modes.

llvm-svn: 360308
2019-05-09 03:31:27 +00:00
..
basic.lookup.argdep [Sema] ADL: Associated namespaces for class types and enumeration types (CWG 1691) 2019-04-22 12:19:00 +00:00
basic.lookup.classref
basic.lookup.elab
basic.lookup.qual Restore pre-r335182 behavior for naming inherited constructors as 2018-06-22 19:50:19 +00:00
basic.lookup.udir
basic.lookup.unqual [c++20] Implement P0846R0: allow (ADL-only) calls to template-ids whose 2019-05-09 03:31:27 +00:00