RequirementMachine: Rename some RuleBuilder methods for clarity

Author: slavapestov

lib/AST/RequirementMachine/RequirementLowering.cpp

@@ -1047,7 +1047,13 @@ ProtocolDependenciesRequest::evaluate(Evaluator &evaluator,
 // Building rewrite rules from desugared requirements.
 //
 
-void RuleBuilder::addRequirements(ArrayRef<Requirement> requirements) {
+/// For building a rewrite system for a generic signature from canonical
+/// requirements.
+void RuleBuilder::initWithGenericSignatureRequirements(
+    ArrayRef<Requirement> requirements) {
+  assert(!Initialized);
+  Initialized = 1;
+
   // Collect all protocols transitively referenced from these requirements.
   for (auto req : requirements) {
     if (req.getKind() == RequirementKind::Conformance) {
@@ -1062,7 +1068,13 @@ void RuleBuilder::addRequirements(ArrayRef<Requirement> requirements) {
     addRequirement(req, /*proto=*/nullptr, /*requirementID=*/None);
 }
 
-void RuleBuilder::addRequirements(ArrayRef<StructuralRequirement> requirements) {
+/// For building a rewrite system for a generic signature from user-written
+/// requirements.
+void RuleBuilder::initWithWrittenRequirements(
+    ArrayRef<StructuralRequirement> requirements) {
+  assert(!Initialized);
+  Initialized = 1;
+
   // Collect all protocols transitively referenced from these requirements.
   for (auto req : requirements) {
     if (req.req.getKind() == RequirementKind::Conformance) {
@@ -1080,7 +1092,11 @@ void RuleBuilder::addRequirements(ArrayRef<StructuralRequirement> requirements)
 /// For building a rewrite system for a protocol connected component from
 /// user-written requirements. Used when actually building requirement
 /// signatures.
-void RuleBuilder::addProtocols(ArrayRef<const ProtocolDecl *> protos) {
+void RuleBuilder::initWithProtocolWrittenRequirements(
+    ArrayRef<const ProtocolDecl *> protos) {
+  assert(!Initialized);
+  Initialized = 1;
+
   for (auto *proto : protos) {
     ReferencedProtocols.insert(proto);
   }

lib/AST/RequirementMachine/RequirementLowering.h

@@ -111,16 +111,21 @@ struct RuleBuilder {
 
   /// Enables debugging output. Controlled by the -dump-requirement-machine
   /// frontend flag.
-  bool Dump;
+  unsigned Dump : 1;
+
+  /// Used to ensure the initWith*() methods are only called once.
+  unsigned Initialized : 1;
 
   RuleBuilder(RewriteContext &ctx,
               llvm::DenseSet<const ProtocolDecl *> &referencedProtocols)
-      : Context(ctx), ReferencedProtocols(referencedProtocols),
-        Dump(ctx.getASTContext().LangOpts.DumpRequirementMachine) {}
-
-  void addRequirements(ArrayRef<Requirement> requirements);
-  void addRequirements(ArrayRef<StructuralRequirement> requirements);
-  void addProtocols(ArrayRef<const ProtocolDecl *> proto);
+      : Context(ctx), ReferencedProtocols(referencedProtocols) {
+    Dump = ctx.getASTContext().LangOpts.DumpRequirementMachine;
+    Initialized = 0;
+  }
+
+  void initWithGenericSignatureRequirements(ArrayRef<Requirement> requirements);
+  void initWithWrittenRequirements(ArrayRef<StructuralRequirement> requirements);
+  void initWithProtocolWrittenRequirements(ArrayRef<const ProtocolDecl *> proto);
   void addReferencedProtocol(const ProtocolDecl *proto);
   void collectRulesFromReferencedProtocols();
 

lib/AST/RequirementMachine/RequirementMachine.cpp

@@ -91,7 +91,7 @@ RequirementMachine::initWithGenericSignature(CanGenericSignature sig) {
   // Collect the top-level requirements, and all transtively-referenced
   // protocol requirement signatures.
   RuleBuilder builder(Context, System.getReferencedProtocols());
-  builder.addRequirements(sig.getRequirements());
+  builder.initWithGenericSignatureRequirements(sig.getRequirements());
 
   // Add the initial set of rewrite rules to the rewrite system.
   System.initialize(/*recordLoops=*/false,
@@ -135,7 +135,7 @@ RequirementMachine::initWithProtocols(ArrayRef<const ProtocolDecl *> protos) {
   }
 
   RuleBuilder builder(Context, System.getReferencedProtocols());
-  builder.addProtocols(protos);
+  builder.initWithProtocolWrittenRequirements(protos);
 
   // Add the initial set of rewrite rules to the rewrite system.
   System.initialize(/*recordLoops=*/true, protos,
@@ -182,7 +182,7 @@ RequirementMachine::initWithWrittenRequirements(
   // Collect the top-level requirements, and all transtively-referenced
   // protocol requirement signatures.
   RuleBuilder builder(Context, System.getReferencedProtocols());
-  builder.addRequirements(requirements);
+  builder.initWithWrittenRequirements(requirements);
 
   // Add the initial set of rewrite rules to the rewrite system.
   System.initialize(/*recordLoops=*/true,