Push immediate function context while transforming lambdas in templates. (#89702)
The following program is [accepted](https://godbolt.org/z/oEc34Trh4) by
Clang, EDG, and MSVC, but rejected by Clang:
```cpp
#include <vector>
consteval auto fn() { return std::vector {1,2,3}; }
template <typename T = int>
void fn2() {
(void)[]() consteval {
for (auto e : fn()) {}
};
}
void caller() {
fn2();
}
```
The stated diagnostic is:
```cpp
<source>:8:21: error: call to consteval function 'fn' is not a constant expression
8 | for (auto e : fn()) {}
```
The body of the lambda should be evaluated as within an immediate
function context when the lambda is marked as `consteval`.
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
GitOrigin-RevId: 5e767bd7d16dcdfc1ad8b32ba399f969dd940f57
3 files changed
