Fix RelBase indexing with composite types

Previously the index data differed when using `Foo, Bar` vs `Foo & Bar`.

Fixes #56255

Author: keith

lib/Index/Index.cpp

@@ -1372,8 +1372,14 @@ bool IndexSwiftASTWalker::reportRelatedRef(ValueDecl *D, SourceLoc Loc, bool isI
 
 bool IndexSwiftASTWalker::reportInheritedTypeRefs(ArrayRef<InheritedEntry> Inherited, Decl *Inheritee) {
   for (auto Base : Inherited) {
-    if (!reportRelatedTypeRef(Base, (SymbolRoleSet) SymbolRole::RelationBaseOf, Inheritee))
-      return false;
+    if (auto *composite = llvm::dyn_cast_or_null<CompositionTypeRepr>(Base.getTypeRepr())) {
+      for (auto *type : composite->getTypes())
+        if (!reportRelatedTypeRef(type, (SymbolRoleSet) SymbolRole::RelationBaseOf, Inheritee))
+          return false;
+    } else {
+      if (!reportRelatedTypeRef(Base, (SymbolRoleSet) SymbolRole::RelationBaseOf, Inheritee))
+        return false;
+    }
   }
   return true;
 }

test/Index/conformances.swift

@@ -57,7 +57,7 @@ protocol P3 {
   func meth2() // CHECK: [[@LINE]]:8 | instance-method/Swift | meth2() | [[P3_meth2_USR:.*]] | Def
 }
 
-class BaseMultiConf {
+class BaseMultiConf { // CHECK: [[@LINE]]:7 | class/Swift | BaseMultiConf | [[BaseMultiConf_USR:.*]] | Def
   func meth2() {} // CHECK: [[@LINE]]:8 | instance-method/Swift | meth2() | [[BaseMultiConf_meth2_USR:.*]] | Def
 }
 extension SubMultiConf {
@@ -79,6 +79,12 @@ class SubMultiConf: BaseMultiConf,P2,P1,P3 { // CHECK: [[@LINE]]:7 | class/Swift
   // CHECK-NOT: [[@LINE-13]]:7 | instance-method
 }
 
+class CompositionType: BaseMultiConf & P1 { // CHECK: [[@LINE]]:7 | class/Swift | CompositionType | [[CompositionType_USR:.*]] | Def
+  // CHECK: [[@LINE-1]]:24 | class/Swift | BaseMultiConf | [[BaseMultiConf_USR]] | Ref,RelBase | rel: 1
+  // CHECK: [[@LINE-2]]:40 | protocol/Swift | P1 | [[P1_USR]] | Ref,RelBase | rel: 1
+  func foo() {}
+}
+
 protocol InheritingP: P1 { // CHECK: [[@LINE]]:10 | protocol/Swift | InheritingP | [[InheritingP_USR:.*]] | Def
   func foo() // CHECK: [[@LINE]]:8 | instance-method/Swift | foo() | [[InheritingP_foo_USR:.*]] | Def,Dyn,RelChild,RelOver | rel: 2
     // CHECK-NEXT: RelOver | instance-method/Swift | foo() | s:14swift_ide_test2P1P3fooyyF