[IDE] Avoid redundant worklist visitor

This is unnecessary since the local conformances for a protocol
can only contain self-conformances, which we don't want to visit
anyway. This can just be a straightforward loop over the local
conformances.

Author: hamishknight

lib/IDE/IDETypeChecking.cpp

@@ -480,7 +480,6 @@ struct SynthesizedExtensionAnalyzer::Implementation {
 
     ExtensionInfoMap InfoMap;
     ExtensionMergeInfoMap MergeInfoMap;
-    std::vector<NominalTypeDecl*> Unhandled;
 
     auto handleExtension = [&](ExtensionDecl *E, bool Synthesized,
                                ExtensionDecl *EnablingE,
@@ -501,31 +500,17 @@ struct SynthesizedExtensionAnalyzer::Implementation {
       }
     };
 
-    // We want to visit the protocols of any normal conformances we see, but
-    // we have to avoid doing this to self-conformances or we can end up with
-    // a cycle.  Otherwise this is cycle-proof on valid code.
-    // We also want to ignore inherited conformances. Members from these will
-    // be included in the class they were inherited from.
-    auto addConformance = [&](ProtocolConformance *Conf) {
-      if (isa<InheritedProtocolConformance>(Conf))
-        return;
-      auto RootConf = Conf->getRootConformance();
-      if (isa<NormalProtocolConformance>(RootConf))
-        Unhandled.push_back(RootConf->getProtocol());
-    };
+    for (auto *LocalConf : Target->getLocalConformances()) {
+      if (isa<InheritedProtocolConformance>(LocalConf))
+        continue;
 
-    for (auto *Conf : Target->getLocalConformances()) {
-      addConformance(Conf);
-    }
-    while (!Unhandled.empty()) {
-      NominalTypeDecl* Back = Unhandled.back();
-      Unhandled.pop_back();
-      for (ExtensionDecl *E : Back->getExtensions()) {
+      auto RootConf = LocalConf->getRootConformance();
+      auto *Conf = dyn_cast<NormalProtocolConformance>(RootConf);
+      if (!Conf)
+        continue;
+
+      for (auto *E : Conf->getProtocol()->getExtensions())
         handleExtension(E, true, nullptr, nullptr);
-      }
-      for (auto *Conf : Back->getLocalConformances()) {
-        addConformance(Conf);
-      }
     }
 
     // Merge with actual extensions.

test/IDE/print_synthesized_extensions.swift

@@ -241,9 +241,9 @@ extension S13 : P5 {
 }
 
 // CHECK1: <synthesized>extension <ref:Struct>S1</ref> where <ref:GenericTypeParam>T</ref> : <ref:module>print_synthesized_extensions</ref>.<ref:Protocol>P2</ref> {
-// CHECK1-NEXT:     <decl:Func>public func <loc>p2member()</loc></decl>
 // CHECK1-NEXT:     <decl:Func>public func <loc>ef1(<decl:Param>t: <ref:GenericTypeParam>T</ref></decl>)</loc></decl>
 // CHECK1-NEXT:     <decl:Func>public func <loc>ef2(<decl:Param>t: <ref:module>print_synthesized_extensions</ref>.<ref:Struct>S2</ref></decl>)</loc></decl>
+// CHECK1-NEXT:     <decl:Func>public func <loc>p2member()</loc></decl>
 // CHECK1-NEXT: }</synthesized>
 
 // CHECK2:  <synthesized>extension <ref:Struct>S1</ref> where <ref:GenericTypeParam>T</ref> : <ref:module>print_synthesized_extensions</ref>.<ref:Protocol>P3</ref>  {
@@ -410,4 +410,4 @@ extension S14 : P14 where repeat each T: Hashable {}
 
 // CHECK17:      <synthesized>extension <ref:Struct>S14</ref> {
 // CHECK17-NEXT:   <decl:Func>public func <loc>foo<each <ref:GenericTypeParam>T</ref>>(<decl:Param>_: repeat each <ref:GenericTypeParam>T</ref></decl>)</loc> where Pack{repeat each <ref:GenericTypeParam>T</ref>} : <ref:Protocol>Equatable</ref></decl>
-// CHECK17-NEXT: }</synthesized>
+// CHECK17-NEXT: }</synthesized>