averello/swift-mirror
1
0
Fork 0
mirror of https://github.com/apple/swift.git synced 2025-12-21 12:14:44 +01:00
Code Issues Packages Projects Releases Wiki Activity

AST: Use availability to disambiguate multiple overlapping conformances

Browse Source 
If a conformance is found in an imported module as well as the current module,
and one of the two conformances is conditionally unavailable on the current
deployment target, pick the one that is always available.

Fixes <rdar://problem/78633800>.
This commit is contained in:
Slava Pestov
2021-06-07 00:44:40 -04:00
parent c139bb4a1c
commit a250688a50
6 changed files with 92 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
lib/AST/ConformanceLookupTable.cpp
View File

@@ -529,6 +529,18 @@ ConformanceLookupTable::Ordering ConformanceLookupTable::compareConformances(
ConformanceEntry *lhs,
ConformanceEntry *rhs,
bool &diagnoseSuperseded) {
// If only one of the conformances is unconditionally available on the
// current deployment target, pick that one.
//
// FIXME: Conformance lookup should really depend on source location for
// this to be 100% correct.
if (lhs->getDeclContext()->isAlwaysAvailableConformanceContext() !=
rhs->getDeclContext()->isAlwaysAvailableConformanceContext()) {
return (lhs->getDeclContext()->isAlwaysAvailableConformanceContext()
? Ordering::Before
: Ordering::After);
}
// If one entry is fixed and the other is not, we have our answer.
if (lhs->isFixed() != rhs->isFixed()) {
// If the non-fixed conformance is not replaceable, we have a failure to