RequirementMachine: Hook up AbstractGenericSignatureRequestRQM to -requirement-machine-generic-signatures flag

Author: slavapestov

lib/AST/GenericSignatureBuilder.cpp

@@ -8559,24 +8559,62 @@ AbstractGenericSignatureRequest::evaluate(
         canSignatureResult.getInt());
   }
 
-  // Create a generic signature that will form the signature.
-  GenericSignatureBuilder builder(ctx);
-  if (baseSignature)
-    builder.addGenericSignature(baseSignature);
+  auto buildViaGSB = [&]() {
+    // Create a generic signature that will form the signature.
+    GenericSignatureBuilder builder(ctx);
+    if (baseSignature)
+      builder.addGenericSignature(baseSignature);
 
-  auto source =
-    GenericSignatureBuilder::FloatingRequirementSource::forAbstract();
+    auto source =
+      GenericSignatureBuilder::FloatingRequirementSource::forAbstract();
 
-  for (auto param : addedParameters)
-    builder.addGenericParameter(param);
+    for (auto param : addedParameters)
+      builder.addGenericParameter(param);
 
-  for (const auto &req : addedRequirements)
-    builder.addRequirement(req, source, nullptr);
+    for (const auto &req : addedRequirements)
+      builder.addRequirement(req, source, nullptr);
 
-  bool hadError = builder.hadAnyError();
-  auto result = std::move(builder).computeGenericSignature(
-      /*allowConcreteGenericParams=*/true);
-  return GenericSignatureWithError(result, hadError);
+    bool hadError = builder.hadAnyError();
+    auto result = std::move(builder).computeGenericSignature(
+        /*allowConcreteGenericParams=*/true);
+    return GenericSignatureWithError(result, hadError);
+  };
+
+  auto buildViaRQM = [&]() {
+    return evaluateOrDefault(
+        ctx.evaluator,
+        AbstractGenericSignatureRequestRQM{
+          baseSignature.getPointer(),
+          std::move(addedParameters),
+          std::move(addedRequirements)},
+        GenericSignatureWithError());
+  };
+
+  switch (ctx.LangOpts.RequirementMachineGenericSignatures) {
+  case RequirementMachineMode::Disabled:
+    return buildViaGSB();
+
+  case RequirementMachineMode::Enabled:
+    return buildViaRQM();
+
+  case RequirementMachineMode::Verify: {
+    auto rqmResult = buildViaRQM();
+    auto gsbResult = buildViaGSB();
+
+    if (!rqmResult.getPointer() && !gsbResult.getPointer())
+      return gsbResult;
+
+    if (!rqmResult.getPointer()->isEqual(gsbResult.getPointer())) {
+      llvm::errs() << "RequirementMachine generic signature minimization is broken:\n";
+      llvm::errs() << "RequirementMachine says:      " << rqmResult.getPointer() << "\n";
+      llvm::errs() << "GenericSignatureBuilder says: " << gsbResult.getPointer() << "\n";
+
+      abort();
+    }
+
+    return gsbResult;
+  }
+  }
 }
 
 GenericSignatureWithError