Close https://github.com/llvm/llvm-project/issues/71034
See
https://discourse.llvm.org/t/rfc-c-20-modules-introduce-thin-bmi-and-decls-hash/74755
This patch introduces reduced BMI, which doesn't contain the definitions
of functions and variables if its definitions won't contribute to the
ABI.
Testing is a big part of the patch. We want to make sure the reduced BMI
contains the same behavior with the existing and relatively stable
fatBMI. This is pretty helpful for further reduction.
The user interfaces part it left to following patches to ease the
reviewing.
Close https://github.com/llvm/llvm-project/issues/60890.
For the following example:
```
export module a;
export template<typename T>
struct a {
friend void aa(a) requires(true) {
}
};
```
```
export module b;
import a;
struct b {
a<int> m;
};
```
```
export module c;
import a;
struct c {
void f() const {
aa(a<int>());
}
};
```
```
import a;
import b;
import c;
void d() {
aa(a<int>());
}
```
The current clang will reject this incorrectly. The reason is that the
require clause will be replaced with the evaluated version
(efae3174f0/clang/lib/Sema/SemaConcept.cpp (L664-L665)).
In module 'b', the friend function is instantiated but not used so the
require clause of the friend function is `(true)`. However, in module
'c', the friend function is used so the require clause is `true`. So
deserializer classify these two function to two different functions
instead of one. Then here is the bug report.
The proposed solution is to try to compare the trailing require clause
of the primary template when performing ODR checking.
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D144626
Close https://github.com/llvm/llvm-project/issues/60890.
For the following example:
```
export module a;
export template<typename T>
struct a {
friend void aa(a) requires(true) {
}
};
```
```
export module b;
import a;
struct b {
a<int> m;
};
```
```
export module c;
import a;
struct c {
void f() const {
aa(a<int>());
}
};
```
```
import a;
import b;
import c;
void d() {
aa(a<int>());
}
```
The current clang will reject this incorrectly. The reason is that the
require clause will be replaced with the evaluated version
(efae3174f0/clang/lib/Sema/SemaConcept.cpp (L664-L665)).
In module 'b', the friend function is instantiated but not used so the
require clause of the friend function is `(true)`. However, in module
'c', the friend function is used so the require clause is `true`. So
deserializer classify these two function to two different functions
instead of one. Then here is the bug report.
The proposed solution is to try to compare the trailing require clause
of the primary template when performing ODR checking.
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D144626
