C++Interop: Relax some noncopyable generics assertions

Author: slavapestov

lib/AST/SwiftNameTranslation.cpp

@@ -283,17 +283,19 @@ swift::cxx_translation::getDeclRepresentation(const ValueDecl *VD) {
   // Generic requirements are not yet supported in C++.
   if (genericSignature) {
 
-    // FIXME: We're using getRequirementsWithInverses() here as a shortcut for
-    // checking for "no requirements except the implied Copyable ones".
+    // FIXME: This should use getRequirements() and actually
+    // support arbitrary requirements. We don't really want
+    // to use getRequirementsWithInverses() here.
     //
-    // Eventually you don't want to call getRequirementsWithInverses() at all;
-    // instead, the code here should walk the desugared requirements of the
-    // signature directly and handle everything.
+    // For now, we use the inverse transform as a quick way to
+    // check for the "default" generic signature where each
+    // generic parameter is Copyable and Escapable, but not
+    // subject to any other requirements; that's exactly the
+    // generic signature that C++ interop supports today.
     SmallVector<Requirement, 2> reqs;
     SmallVector<InverseRequirement, 2> inverseReqs;
     genericSignature->getRequirementsWithInverses(reqs, inverseReqs);
-    assert(inverseReqs.empty() && "Non-copyable generics not supported here!");
-    if (!reqs.empty())
+    if (!reqs.empty() || !inverseReqs.empty())
       return {Unsupported, UnrepresentableGenericRequirements};
   }
 

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -386,11 +386,17 @@ class DeclAndTypePrinter::Implementation
             SmallVector<Requirement, 2> reqs;
             SmallVector<InverseRequirement, 2> inverseReqs;
             if (auto sig = ed->getGenericSignature()) {
+              // FIXME: This should use getRequirements() and actually
+              // support arbitrary requirements. We don't really want
+              // to use getRequirementsWithInverses() here.
+              //
+              // For now, we use the inverse transform as a quick way to
+              // check for the "default" generic signature where each
+              // generic parameter is Copyable and Escapable, but not
+              // subject to any other requirements; that's exactly the
+              // generic signature that C++ interop supports today.
               sig->getRequirementsWithInverses(reqs, inverseReqs);
-              assert(inverseReqs.empty() &&
-                     "Non-copyable generics not supported here!");
-              // FIXME: support requirements.
-              if (!reqs.empty())
+              if (!reqs.empty() || !inverseReqs.empty())
                 continue;
             }
             printMembers(ed->getMembers());

lib/PrintAsClang/PrintClangFunction.cpp

@@ -701,13 +701,19 @@ ClangRepresentation DeclAndTypeClangFunctionPrinter::printFunctionSignature(
   if (FD->isGeneric()) {
     auto Signature = FD->getGenericSignature().getCanonicalSignature();
 
-    // FIXME: Support generic requirements.
+    // FIXME: This should use getRequirements() and actually
+    // support arbitrary requirements. We don't really want
+    // to use getRequirementsWithInverses() here.
+    //
+    // For now, we use the inverse transform as a quick way to
+    // check for the "default" generic signature where each
+    // generic parameter is Copyable and Escapable, but not
+    // subject to any other requirements; that's exactly the
+    // generic signature that C++ interop supports today.
     SmallVector<Requirement, 2> reqs;
     SmallVector<InverseRequirement, 2> inverseReqs;
     Signature->getRequirementsWithInverses(reqs, inverseReqs);
-    assert(inverseReqs.empty() && "Non-copyable generics not supported here!");
-
-    if (!reqs.empty())
+    if (!reqs.empty() || !inverseReqs.empty())
       return ClangRepresentation::unsupported;
     // Print the template and requires clauses for this function.
     if (kind == FunctionSignatureKind::CxxInlineThunk)

lib/PrintAsClang/PrintClangValueType.cpp

@@ -194,7 +194,15 @@ void ClangValueTypePrinter::printValueTypeDecl(
   if (typeDecl->isGeneric()) {
     genericSignature = typeDecl->getGenericSignature();
 
-    // FIXME: Support generic requirements.
+    // FIXME: This should use getRequirements() and actually
+    // support arbitrary requirements. We don't really want
+    // to use getRequirementsWithInverses() here.
+    //
+    // For now, we use the inverse transform as a quick way to
+    // check for the "default" generic signature where each
+    // generic parameter is Copyable and Escapable, but not
+    // subject to any other requirements; that's exactly the
+    // generic signature that C++ interop supports today.
     SmallVector<Requirement, 2> reqs;
     SmallVector<InverseRequirement, 2> inverseReqs;
     genericSignature->getRequirementsWithInverses(reqs, inverseReqs);