[OpenMP-5.2] deprecate delimited form of 'declare target' (#145854)
According to OpenMP 5.2 (Section 7.8.2), the directive name `declare
target` may be used as a synonym for `begin declare target` only when no
clauses are specified. This clause-less delimited form is now deprecated
and should emit a deprecation warning.
```
// Deprecated usage (should trigger warning):
#pragma omp declare target // deprecated in OpenMP 5.2
void foo1() {
}
#pragma omp end declare target
// Valid usage with clause (should not trigger warning):
#pragma omp declare target enter(foo2)
void foo2() {
}
```
```
// Recommended replacement for deprecated delimited form:
#pragma omp begin declare target
void foo() {
}
#pragma omp end declare target
```
---------
Co-authored-by: urvi-rav <urvi.rav@hpe.com>
llvm-project
8055c0f3 - [OpenMP-5.2] deprecate delimited form of 'declare target' (#145854)
