[mlir][tblgen] Emit interface decls in definition order in the .td file

[springerm]

Summary

Interface decls were previously sorted by name. This lead to problems when using interface inheritance when both interfaces are defined in the same .td file. The derived interface must appear after the base interface, otherwise the generated C++ will not compile.

With this change, interfaces will compile as long as the base interface is defined before derived interfaces in the .td file.

[rriddle]

Nice

mlir/tools/mlir-tblgen/OpInterfacesGen.cpp

void InterfaceGenerator::emitInterfaceDecl(const Interface &interface) {
   os << "}// namespace detail\n";
 
   for (StringRef ns : llvm::reverse(namespaces))
     os << "} // namespace " << ns << "\n";
 }
 
 bool InterfaceGenerator::emitInterfaceDecls() {
   llvm::emitSourceFileHeader("Interface Declarations", os);
-
-  for (const llvm::Record *def : defs)
+  // Sort according to ID, so defs are emitted in the order in which they appear
+  // in the Tablegen file.
+  std::vector<llvm::Record *> sortedDefs(defs);
+  llvm::sort(sortedDefs, [](llvm::Record *lhs, llvm::Record *rhs) {
+    return lhs->getID() < rhs->getID();
+  });
+  for (const llvm::Record *def : sortedDefs)
     emitInterfaceDecl(Interface(def));
-  for (const llvm::Record *def : defs)
+  for (const llvm::Record *def : sortedDefs)
     emitModelMethodsDef(Interface(def));
   return false;
 }
 
 //===----------------------------------------------------------------------===//
 // GEN: Interface documentation
 //===----------------------------------------------------------------------===//