Currently, due to the incomplete implementation of p0588r1, the
instantiation of lambda expressions leads to the instantiation of the
body. And `EvaluateConstraints` is false during the instantiation of the
body, which causes crashes during the instantiation of the return type
requirement:
```cpp
template<typename T> concept doesnt_matter = true;
template<class T>
concept test =
[]{
return requires(T t) {
{ t } -> doesnt_matter; // crash
};
}();
static_assert(test<int>);
```
Although a complete implementation of p0588r1 can solve these crashes,
it will take some time. Therefore, this pull request aims to fix these
crashes first.
Fixes https://github.com/llvm/llvm-project/issues/63808
Fixes https://github.com/llvm/llvm-project/issues/64607
Fixes https://github.com/llvm/llvm-project/issues/64086
As reported in GH60642, we asserted when there was a lambda defined in a
template arguments inside of a concept, which caused us to not properly
set up the list of instantiation args. This patch ensures that the
'lambda context decl' correctly falls-through the template argument
instantiation, so that it is available when instantiating the lambda,
and thus, when setting up the lambda instantiation args list.
This reverts commit cecc9a92cfca71c1b6c2a35c5e302ab649496d11.
The problem ended up being how we were handling the lambda-context in
code generation: we were assuming any decl context here would be a
named-decl, but that isn't the case. Instead, we just replace it with
the concept's owning context.
Differential Revision: https://reviews.llvm.org/D136451
This reverts commit b876f6e2f28779211a829d7d4e841fe68885ae20.
Still getting build failures on PPC AIX that aren't obvious what is causing
them, so reverting while I try to figure this out.
This reverts commit b7c922607c5ba93db8b893d4ba461052af8317b5.
This seems to cause some problems with some modules related things,
which makes me think I should have updated the version-major in
ast-bit-codes? Going to revert to confirm this was a problem, then
change that and re-try a commit.
As that bug reports, the problem here is that the lambda's
'context-decl' was not set to the concept, and the lambda picked up
template arguments from the concept. SO, we failed to get the correct
template arguments in SemaTemplateInstantiate.
However, a Concept Specialization is NOT a decl, its an expression, so
we weren't able to put the concept in the decl tree like we needed.
This patch introduces a ConceptSpecializationDecl, which is the smallest
type possible to use for this purpose, containing only the template
arguments.
The net memory impliciation of this is turning a
trailing-objects into a pointer to a type with trailing-objects, so it
should be minor.
As future work, we may consider giving this type more responsibility, or
figuring out how to better merge duplicates, but as this is just a
template-argument collection at the moment, there isn't much value to
it.
Differential Revision: https://reviews.llvm.org/D136451
As fallout of the Deferred Concept Instantiation patch (babdef27c5), we
got a number of reports of a regression, where we asserted when
instantiating a constraint on a generic lambda inside of a variable
template. See: https://github.com/llvm/llvm-project/issues/57958
The problem was that getTemplateInstantiationArgs function only walked
up declaration contexts, and missed that this is not necessarily the
case with a lambda (which can ALSO be in a separate context).
This patch refactors the getTemplateInstantiationArgs function in a way
that is hopefully more readable, and fixes the problem with the concepts
on a generic lambda.
Differential Revision: https://reviews.llvm.org/D134874
As reported in GH #57945, this would crash because the decl context for
the lambda was being loaded via 'getNonClosureContext', which only gets
CODE contexts, so a global lambda was getting 'nullptr' here instead.
This patch does some work to make sure we get a valid/valuable
declcontext here instead.
