[RequirementMachine] Don't suppress redundancy diagnostics when the

non-explicit, non-redundant replacement rule is not in the rewrite
system's minimization domain.

Author: hborla

lib/AST/RequirementMachine/RewriteSystem.cpp

@@ -741,7 +741,8 @@ RewriteSystem::getRedundantRequirements() {
   for (unsigned ruleID : indices(getRules())) {
     auto &rule = getRules()[ruleID];
 
-    if (!rule.isExplicit() && !rule.isPermanent() && !rule.isRedundant())
+    if (!rule.isExplicit() && !rule.isPermanent() && !rule.isRedundant() &&
+        isInMinimizationDomain(rule.getLHS().getRootProtocol()))
       impliedRequirements.insert(ruleID);
 
     if (!rule.isExplicit())

test/Generics/rdar83308672.swift

@@ -40,13 +40,13 @@ protocol G1 {
 // CHECK: rdar83308672.(file).G2@
 // CHECK-NEXT: Requirement signature: <Self where Self.[G2]T : A, Self.[G2]T.[A]X == Self.[G2]T.[A]Y>
 protocol G2 {
-  associatedtype T : A where T : B, T.X == T.Y
+  associatedtype T : A where T : B, T.X == T.Y // expected-warning {{redundant conformance constraint 'Self.T' : 'B'}}
 }
 
 // CHECK: rdar83308672.(file).G3@
 // CHECK-NEXT: Requirement signature: <Self where Self.[G3]T : A, Self.[G3]T.[A]X == Self.[G3]T.[A]Y>
 protocol G3 {
-  associatedtype T : A where T.X == T.Y, T : B
+  associatedtype T : A where T.X == T.Y, T : B // expected-warning {{redundant conformance constraint 'Self.T' : 'B'}}
 }
 
 // CHECK: rdar83308672.(file).G4@

test/Generics/requirement_machine_diagnostics.swift

@@ -152,7 +152,7 @@ protocol P7 : P6 {
   associatedtype AssocP7: P6
 }
 
-// FIXME: diagnose redundant requirement 'AssocP6.Element : P6'
+// expected-warning@+1{{redundant conformance constraint 'Self.AssocP6.Element' : 'P6'}}
 extension P7 where AssocP6.Element : P6,
         AssocP7.AssocP6.Element : P6,
         AssocP6.Element == AssocP7.AssocP6.Element {