Add CppInterOp API Dispatch mechanism by aaronj0 · Pull Request #780 · compiler-research/CppInterOp

aaronj0 · 2026-01-17T11:55:40Z

(fresh PR on top of #730, see #730 (comment))

This PR defines the mechanism which enables dispatching CppInterOp's API without linking to it, preventing any LLVM or Clang symbols from being leaked into the client application.

This allows us to run cppyy without linking to CppInterOp motivated by the use case in ROOT. Can be used to deploy CppInterOp in an environment where dynamic linking is not favourable and the only option is dlopen'ing libClangCppInterOp.so with RTLD_LOCAL

TODO:

Failures in the CPyCppyy build step are expected since it redefines TemplateArgInfo and expects the symbols to match the ones in cppyy-backend, which is no longer the case. Corresponding PR: Adapt Cpp::TemplateArgInfo to match cppyy-backend's CPyCppyy#148 and Migrate to CppInterOp Dispatch, no longer link/load shared lib in Python cppyy-backend#177 to be merged following this PR
clang-format has to be run over all changes, will do that once the PR has been refactored into atomic commits (once approved and ready to be merged)
dev docs to be added explaining how a client would use this system

codecov · 2026-01-17T12:01:57Z

Codecov Report

❌ Patch coverage is 81.81818% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.32%. Comparing base (9d2f4c5) to head (dd612b1).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
include/CppInterOp/Dispatch.h	77.77%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #780      +/-   ##
==========================================
+ Coverage   79.30%   79.32%   +0.02%     
==========================================
  Files           9       11       +2     
  Lines        3933     3966      +33     
==========================================
+ Hits         3119     3146      +27     
- Misses        814      820       +6

Files with missing lines	Coverage Δ
include/CppInterOp/CppInterOp.h	`95.12% <ø> (ø)`
lib/CppInterOp/CXCppInterOp.cpp	`49.56% <ø> (ø)`
lib/CppInterOp/CppInterOp.cpp	`87.73% <ø> (ø)`
lib/CppInterOp/Dispatch.cpp	`100.00% <100.00%> (ø)`
include/CppInterOp/Dispatch.h	`77.77% <77.77%> (ø)`

Files with missing lines	Coverage Δ
include/CppInterOp/CppInterOp.h	`95.12% <ø> (ø)`
lib/CppInterOp/CXCppInterOp.cpp	`49.56% <ø> (ø)`
lib/CppInterOp/CppInterOp.cpp	`87.73% <ø> (ø)`
lib/CppInterOp/Dispatch.cpp	`100.00% <100.00%> (ø)`
include/CppInterOp/Dispatch.h	`77.77% <77.77%> (ø)`

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include/CppInterOp/CppInterOp.h

include/CppInterOp/Dispatch.h

unittests/CppInterOp/CUDATest.cpp

unittests/CppInterOp/FunctionReflectionTest.cpp

github-actions · 2026-01-17T12:27:28Z

unittests/CppInterOp/FunctionReflectionTest.cpp

-TYPED_TEST(CppInterOpTest, FunctionReflectionTestGetClassMethods) {
+// Reusable empty template args vector. In the dispatch mode, passing an empty initializer list {}
+// does not work since the compiler cannot deduce the type for a function pointer
+std::vector<Cpp::TemplateArgInfo> empty_templ_args = {};


warning: variable 'empty_templ_args' can be made static or moved into an anonymous namespace to enforce internal linkage [misc-use-internal-linkage]

Suggested change

std::vector<Cpp::TemplateArgInfo> empty_templ_args = {};

static std::vector<Cpp::TemplateArgInfo> empty_templ_args = {};

unittests/CppInterOp/FunctionReflectionTest.cpp

github-actions · 2026-01-17T12:27:28Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  std::vector<Cpp::TemplateArgInfo> args1 = {C.IntTy.getAsOpaquePtr()};
  std::vector<Cpp::TemplateArgInfo> args2 = {
-      Cpp::GetVariableType(Cpp::GetNamed("a"))};
+      Cpp::GetVariableType(Cpp::GetNamed("a", 0))};


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetVariableType(Cpp::GetNamed("a", 0))};

Cpp::GetVariableType(Cpp::GetNamed("a", nullptr))};

github-actions · 2026-01-17T12:27:28Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  std::vector<Cpp::TemplateArgInfo> args4 = {
-      Cpp::GetVariableType(Cpp::GetNamed("a")),
-      Cpp::GetVariableType(Cpp::GetNamed("a"))};
+      Cpp::GetVariableType(Cpp::GetNamed("a", 0)),


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetVariableType(Cpp::GetNamed("a", 0)),

Cpp::GetVariableType(Cpp::GetNamed("a", nullptr)),

github-actions · 2026-01-17T12:27:28Z

unittests/CppInterOp/FunctionReflectionTest.cpp

-      Cpp::GetVariableType(Cpp::GetNamed("a")),
-      Cpp::GetVariableType(Cpp::GetNamed("a"))};
+      Cpp::GetVariableType(Cpp::GetNamed("a", 0)),
+      Cpp::GetVariableType(Cpp::GetNamed("a", 0))};


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetVariableType(Cpp::GetNamed("a", 0))};

Cpp::GetVariableType(Cpp::GetNamed("a", nullptr))};

github-actions · 2026-01-17T12:27:29Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  std::vector<Cpp::TemplateArgInfo> args1 = {
-      Cpp::GetVariableType(Cpp::GetNamed("a")),
-      Cpp::GetVariableType(Cpp::GetNamed("a"))};
+      Cpp::GetVariableType(Cpp::GetNamed("a", 0)),


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetVariableType(Cpp::GetNamed("a", 0)),

Cpp::GetVariableType(Cpp::GetNamed("a", nullptr)),

vgvassilev · 2026-01-17T13:13:37Z

lib/CppInterOp/Dispatch.cpp

+
+CppFnPtrTy CppGetProcAddress(const char* funcName) {
+  auto it = DispatchMap.find(funcName);
+  if (it == DispatchMap.end())


If this code is reachable we should provide some diagnostic message and a test.

vgvassilev · 2026-01-17T13:14:31Z

unittests/CppInterOp/CUDATest.cpp


  Cpp::CreateInterpreter({}, {"--cuda"});
-  bool success = !Cpp::Declare("#include <cuda.h>");
+  bool success = !Cpp::Declare("#include <cuda.h>", false);


Spell out the default argument names in /**/

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unittests/CppInterOp/FunctionReflectionTest.cpp

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github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  auto S = clang_getDefaultConstructor(make_scope(Decls[0], I));
  void* object_c = nullptr;
-  clang_invoke(S, &object_c, nullptr, 0, nullptr);
+  clang_invoke(S, &object_c, nullptr, 0, 0);


warning: multilevel pointer conversion from 'void **' to 'void *', please use explicit cast [bugprone-multi-level-implicit-pointer-conversion]

clang_invoke(S, &object_c, nullptr, 0, 0); ^

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  auto S = clang_getDefaultConstructor(make_scope(Decls[0], I));
  void* object_c = nullptr;
-  clang_invoke(S, &object_c, nullptr, 0, nullptr);
+  clang_invoke(S, &object_c, nullptr, 0, 0);


warning: use nullptr [modernize-use-nullptr]

Suggested change

clang_invoke(S, &object_c, nullptr, 0, 0);

clang_invoke(S, &object_c, nullptr, 0, nullptr);

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  EXPECT_TRUE(FCI1.getKind() == Cpp::JitCall::kGenericCall);
  Cpp::JitCall FCI2 =
-      Cpp::MakeFunctionCallable(Cpp::GetNamed("f2"));
+      Cpp::MakeFunctionCallable(Cpp::GetNamed("f2", 0));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::MakeFunctionCallable(Cpp::GetNamed("f2", 0));

Cpp::MakeFunctionCallable(Cpp::GetNamed("f2", nullptr));

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  EXPECT_TRUE(FCI2.getKind() == Cpp::JitCall::kGenericCall);
  Cpp::JitCall FCI3 =
-    Cpp::MakeFunctionCallable(Cpp::GetNamed("f3", Cpp::GetNamed("NS")));
+    Cpp::MakeFunctionCallable(Cpp::GetNamed("f3", Cpp::GetNamed("NS", 0)));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::MakeFunctionCallable(Cpp::GetNamed("f3", Cpp::GetNamed("NS", 0)));

Cpp::MakeFunctionCallable(Cpp::GetNamed("f3", Cpp::GetNamed("NS", nullptr)));

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  EXPECT_TRUE(FCI3.getKind() == Cpp::JitCall::kGenericCall);
  Cpp::JitCall FCI4 =
-      Cpp::MakeFunctionCallable(Cpp::GetNamed("f4", Cpp::GetNamed("NS")));
+      Cpp::MakeFunctionCallable(Cpp::GetNamed("f4", Cpp::GetNamed("NS", 0)));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::MakeFunctionCallable(Cpp::GetNamed("f4", Cpp::GetNamed("NS", 0)));

Cpp::MakeFunctionCallable(Cpp::GetNamed("f4", Cpp::GetNamed("NS", nullptr)));

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp


  Cpp::JitCall FCI5 =
-      Cpp::MakeFunctionCallable(Cpp::GetNamed("f5", Cpp::GetNamed("NS")));
+      Cpp::MakeFunctionCallable(Cpp::GetNamed("f5", Cpp::GetNamed("NS", 0)));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::MakeFunctionCallable(Cpp::GetNamed("f5", Cpp::GetNamed("NS", 0)));

Cpp::MakeFunctionCallable(Cpp::GetNamed("f5", Cpp::GetNamed("NS", nullptr)));

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  )");

-  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C");
+  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", 0);


warning: do not use C-style cast to convert between unrelated types [cppcoreguidelines-pro-type-cstyle-cast]

clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", 0); ^

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  )");

-  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C");
+  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", 0);


warning: no header providing "clang::NamedDecl" is directly included [misc-include-cleaner]

clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", 0); ^

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  )");

-  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C");
+  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", 0);


warning: use nullptr [modernize-use-nullptr]

Suggested change

clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", 0);

clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C", nullptr);

github-actions · 2026-01-20T12:06:15Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  )");

-  Cpp::TCppScope_t set_5 = Cpp::GetNamed("set_5");
+  Cpp::TCppScope_t set_5 = Cpp::GetNamed("set_5", 0);


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::TCppScope_t set_5 = Cpp::GetNamed("set_5", 0);

Cpp::TCppScope_t set_5 = Cpp::GetNamed("set_5", nullptr);

github-actions

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There were too many comments to post at once. Showing the first 10 out of 96. Check the log or trigger a new build to see more.

github-actions · 2026-01-21T14:11:57Z

unittests/CppInterOp/FunctionReflectionTest.cpp


  Cpp::TCppScope_t TypedefToPrivateClass =
-      Cpp::GetNamed("TypedefToPrivateClass");
+      Cpp::GetNamed("TypedefToPrivateClass", 0);


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetNamed("TypedefToPrivateClass", 0);

Cpp::GetNamed("TypedefToPrivateClass", nullptr);

github-actions · 2026-01-21T14:11:57Z

unittests/CppInterOp/FunctionReflectionTest.cpp

    };
  )");
-  Cpp::TCppScope_t TOperator = Cpp::GetNamed("TOperator");
+  Cpp::TCppScope_t TOperator = Cpp::GetNamed("TOperator", 0);


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::TCppScope_t TOperator = Cpp::GetNamed("TOperator", 0);

Cpp::TCppScope_t TOperator = Cpp::GetNamed("TOperator", nullptr);

github-actions · 2026-01-21T14:11:57Z

unittests/CppInterOp/FunctionReflectionTest.cpp


-  Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1"));
-  Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2"));
+  Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1", 0));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1", 0));

Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1", nullptr));

github-actions · 2026-01-21T14:11:57Z

unittests/CppInterOp/FunctionReflectionTest.cpp

-  Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1"));
-  Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2"));
+  Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1", 0));
+  Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2", 0));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2", 0));

Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2", nullptr));

github-actions · 2026-01-21T14:11:58Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  operators.clear();
-  Cpp::GetOperator(Cpp::GetScope("N2", Cpp::GetScope("N1")), Cpp::OP_Plus,
-                   operators);
+  Cpp::GetOperator(Cpp::GetScope("N2", Cpp::GetScope("N1", 0)), Cpp::Operator::OP_Plus,


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetOperator(Cpp::GetScope("N2", Cpp::GetScope("N1", 0)), Cpp::Operator::OP_Plus,

Cpp::GetOperator(Cpp::GetScope("N2", Cpp::GetScope("N1", nullptr)), Cpp::Operator::OP_Plus,

github-actions · 2026-01-21T14:11:58Z

unittests/CppInterOp/FunctionReflectionTest.cpp


  std::vector<Cpp::TCppFunction_t> unresolved_candidate_methods;
-  Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std"),
+  Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std", 0),


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std", 0),

Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std", nullptr),

github-actions · 2026-01-21T14:11:58Z

unittests/CppInterOp/FunctionReflectionTest.cpp

+  Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std", 0),
                                unresolved_candidate_methods);
-  Cpp::TCppType_t p = Cpp::GetTypeFromScope(Cpp::GetNamed("p"));
+  Cpp::TCppType_t p = Cpp::GetTypeFromScope(Cpp::GetNamed("p", 0));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::TCppType_t p = Cpp::GetTypeFromScope(Cpp::GetNamed("p", 0));

Cpp::TCppType_t p = Cpp::GetTypeFromScope(Cpp::GetNamed("p", nullptr));

github-actions · 2026-01-21T14:11:58Z

unittests/CppInterOp/FunctionReflectionTest.cpp

      unresolved_candidate_methods, {},
-      {Cpp::GetVariableType(Cpp::GetNamed("tuple_one")),
-       Cpp::GetVariableType(Cpp::GetNamed("tuple_two"))});
+      {Cpp::GetVariableType(Cpp::GetNamed("tuple_one", 0)),


warning: use nullptr [modernize-use-nullptr]

Suggested change

{Cpp::GetVariableType(Cpp::GetNamed("tuple_one", 0)),

{Cpp::GetVariableType(Cpp::GetNamed("tuple_one", nullptr)),

github-actions · 2026-01-21T14:11:58Z

unittests/CppInterOp/FunctionReflectionTest.cpp

-      {Cpp::GetVariableType(Cpp::GetNamed("tuple_one")),
-       Cpp::GetVariableType(Cpp::GetNamed("tuple_two"))});
+      {Cpp::GetVariableType(Cpp::GetNamed("tuple_one", 0)),
+       Cpp::GetVariableType(Cpp::GetNamed("tuple_two", 0))});


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetVariableType(Cpp::GetNamed("tuple_two", 0))});

Cpp::GetVariableType(Cpp::GetNamed("tuple_two", nullptr))});

github-actions · 2026-01-21T14:11:58Z

unittests/CppInterOp/FunctionReflectionTest.cpp


  Cpp::TCppScope_t bar =
-      Cpp::GetNamed("bar", Cpp::GetScope("EnumFunctionSameName"));
+      Cpp::GetNamed("bar", Cpp::GetScope("EnumFunctionSameName", 0));


warning: use nullptr [modernize-use-nullptr]

Suggested change

Cpp::GetNamed("bar", Cpp::GetScope("EnumFunctionSameName", 0));

Cpp::GetNamed("bar", Cpp::GetScope("EnumFunctionSameName", nullptr));

unittests/CMakeLists.txt

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lib/CppInterOp/Dispatch.cpp

unittests/CppInterOp/DispatchTest.cpp

vgvassilev · 2026-01-21T19:01:45Z

include/CppInterOp/Dispatch.h

+
+  // Sanity check to verify that critical (and consequently all) functions are loaded
+  if (!GetInterpreter || !CreateInterpreter) {
+    std::cerr << "[CppInterOp] Failed to load critical functions\n";


Suggested change

std::cerr << "[CppInterOp] Failed to load critical functions\n";

std::cerr << "[CppInterOp Dispatch] Failed to load critical functions\n";

vgvassilev · 2026-01-21T19:05:03Z

unittests/CppInterOp/ScopeReflectionTest.cpp


  Interp->declare(code);
-  Cpp::TCppScope_t ns_N1 = Cpp::GetNamed("N1");
+  Cpp::TCppScope_t ns_N1 = Cpp::GetNamed("N1", 0);


Suggested change

Cpp::TCppScope_t ns_N1 = Cpp::GetNamed("N1", 0);

Cpp::TCppScope_t ns_N1 = Cpp::GetNamed("N1", DFLT_0);

vgvassilev · 2026-01-21T19:05:22Z

unittests/CppInterOp/ScopeReflectionTest.cpp

  EXPECT_EQ(get_base_class_name(Decls[10], 0), "<unnamed>");

-  auto *VD = Cpp::GetNamed("var");
+  auto *VD = Cpp::GetNamed("var", 0);


Suggested change

auto *VD = Cpp::GetNamed("var", 0);

auto *VD = Cpp::GetNamed("var", DFLT_0);

vgvassilev · 2026-01-21T19:05:30Z

unittests/CppInterOp/ScopeReflectionTest.cpp

  EXPECT_EQ(Cpp::GetCompleteName(TC1_A_Decl), "TC1<A>");

-  auto* VD1 = Cpp::GetNamed("var1");
+  auto* VD1 = Cpp::GetNamed("var1", 0);


Suggested change

auto* VD1 = Cpp::GetNamed("var1", 0);

auto* VD1 = Cpp::GetNamed("var1", DFLT_0);

vgvassilev · 2026-01-21T19:06:01Z

unittests/CppInterOp/ScopeReflectionTest.cpp

  std::vector<Cpp::TemplateArgInfo> args1 = {C.IntTy.getAsOpaquePtr()};
  auto Instance1 = Cpp::InstantiateTemplate(Decls[0], args1.data(),
-                                            /*type_size*/ args1.size());
+                                            /*type_size*/ args1.size(), false);


Suggested change

/*type_size*/ args1.size(), false);

/*type_size*/ args1.size() DFLT_FALSE);

vgvassilev · 2026-01-21T19:06:26Z

unittests/CppInterOp/ScopeReflectionTest.cpp

  std::vector<Cpp::TemplateArgInfo> args1 = {C.IntTy.getAsOpaquePtr()};
  auto Instance1 = Cpp::InstantiateTemplate(Decls[0], args1.data(),
-                                            /*type_size*/ args1.size());
+                                            /*type_size*/ args1.size(), false);


Suggested change

/*type_size*/ args1.size(), false);

/*type_size*/ args1.size() DFLT_FALSE);

vgvassilev · 2026-01-21T19:06:38Z

unittests/CppInterOp/ScopeReflectionTest.cpp


  auto Instance2 = Cpp::InstantiateTemplate(Decls[1], nullptr,
-                                            /*type_size*/ 0);
+                                            /*type_size*/ 0, false);


Suggested change

/*type_size*/ 0, false);

/*type_size*/ 0 DFLT_FALSE);

vgvassilev · 2026-01-21T19:06:50Z

unittests/CppInterOp/ScopeReflectionTest.cpp

  std::vector<Cpp::TemplateArgInfo> args3 = {C.IntTy.getAsOpaquePtr()};
  auto Instance3 = Cpp::InstantiateTemplate(Decls[2], args3.data(),
-                                            /*type_size*/ args3.size());
+                                            /*type_size*/ args3.size(), false);


Suggested change

/*type_size*/ args3.size(), false);

/*type_size*/ args3.size() DFLT_FALSE);

vgvassilev · 2026-01-21T19:07:09Z

unittests/CppInterOp/ScopeReflectionTest.cpp

+  auto *v1 = Cpp::GetNamed("v1", 0);
+  auto *v2 = Cpp::GetNamed("v2", 0);
+  auto *v3 = Cpp::GetNamed("v3", 0);


Suggested change

auto *v1 = Cpp::GetNamed("v1", 0);

auto *v2 = Cpp::GetNamed("v2", 0);

auto *v3 = Cpp::GetNamed("v3", 0);

auto *v1 = Cpp::GetNamed("v1", DFLT_0);

auto *v2 = Cpp::GetNamed("v2", DFLT_0);

auto *v3 = Cpp::GetNamed("v3", DFLT_0);

unittests/CppInterOp/Utils.h

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There were too many comments to post at once. Showing the first 10 out of 27. Check the log or trigger a new build to see more.

unittests/CppInterOp/DispatchTest.cpp

unittests/CppInterOp/FunctionReflectionTest.cpp

github-actions · 2026-01-23T16:05:55Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  )");

-  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C");
+  clang::NamedDecl* ClassC = (clang::NamedDecl*)Cpp::GetNamed("C" DFLT_NULLPTR);


warning: do not use C-style cast to convert between unrelated types [cppcoreguidelines-pro-type-cstyle-cast]

clang::NamedDecl* ClassC = (clang::NamedDecl*)Cpp::GetNamed("C" DFLT_NULLPTR); ^

github-actions · 2026-01-23T16:05:55Z

unittests/CppInterOp/FunctionReflectionTest.cpp

  )");

-  clang::NamedDecl *ClassC = (clang::NamedDecl*)Cpp::GetNamed("C");
+  clang::NamedDecl* ClassC = (clang::NamedDecl*)Cpp::GetNamed("C" DFLT_NULLPTR);


warning: no header providing "clang::NamedDecl" is directly included [misc-include-cleaner]

clang::NamedDecl* ClassC = (clang::NamedDecl*)Cpp::GetNamed("C" DFLT_NULLPTR); ^

unittests/CppInterOp/FunctionReflectionTest.cpp

github-actions

clang-tidy made some suggestions

unittests/CppInterOp/DispatchTest.cpp

github-actions · 2026-01-23T16:58:32Z

unittests/CppInterOp/DispatchTest.cpp

+
+  std::string mangled_add_int;
+  std::string mangled_add_double;
+  compat::maybeMangleDeclName(Add_int, mangled_add_int);


warning: no header providing "compat::maybeMangleDeclName" is directly included [misc-include-cleaner]

unittests/CppInterOp/DispatchTest.cpp:6:

- #include "gtest/gtest.h" + #include "/github/workspace/lib/CppInterOp/Compatibility.h" + #include "gtest/gtest.h"

unittests/CppInterOp/FunctionReflectionTest.cpp

unittests/CppInterOp/ScopeReflectionTest.cpp

unittests/CppInterOp/Utils.cpp

github-actions

clang-tidy made some suggestions

github-actions · 2026-01-23T17:48:34Z

unittests/CppInterOp/DispatchTest.cpp

+
+  std::string mangled_add_int;
+  std::string mangled_add_double;
+  compat::maybeMangleDeclName(Add_int, mangled_add_int);


warning: no header providing "compat::maybeMangleDeclName" is directly included [misc-include-cleaner]

unittests/CppInterOp/DispatchTest.cpp:7:

- #include "gtest/gtest.h" + #include "/github/workspace/lib/CppInterOp/Compatibility.h" + #include "gtest/gtest.h"

github-actions · 2026-01-23T17:48:34Z

unittests/CppInterOp/Utils.cpp

+  DispatchInitializer& operator=(DispatchInitializer&&) noexcept = default;
+};
+// FIXME: Make this threadsafe by moving it as a function static.
+DispatchInitializer g_dispatch_init;


warning: variable 'g_dispatch_init' is non-const and globally accessible, consider making it const [cppcoreguidelines-avoid-non-const-global-variables]

DispatchInitializer g_dispatch_init; ^

vgvassilev

Lgtm!

… Cpp

Defines the mechanism which enables dispatching of the CppInterOp API without linking, preventing any LLVM or Clang symbols from being leaked into the client application. This is achieved using a symbol-address table and an address lookup through a C symbol allowing clients to dlopen CppInterOp with RTLD_LOCAL, and automatically assign the API during runtime. This alternate approach is particularly useful in scenarios where CppInterOp is loaded dynamically alongside other tools/libraries/packages that also rely on LLVM. With cppyy, importing tools like `numba` or `pygame` that come bundled with a statically linked copy of LLVM, leads to symbol interposition and crashes. The dispatch mechanism solves this by solely relying on a C interface, which returns a pointer to the address of a requested function, which can be cast to the appropriate API type and invoked as needed. An example can be found in `unittests/CppInterOp/DispatchTest.cpp`. For a user, this system is completely automated via the `Dispatch.h` header file, which maintains a symbol-address map for a fast look-up through a C symbol (`CppGetProcAddress`) which is fetched via `dlsym`. The provided macro system then handles all the declarations on the client end with the inclusion of the header: ```cpp ``` At this point, the expansions already provide the same API surface as the standard CppInterOp library, except that the declarations require to be added to a translation unit for the client application. This can be done by adding the following preprocessor directive in one of the source files: ```cpp CPPINTEROP_API_TABLE ``` This creates the necessary function pointers in the `Cpp` namespace, which can then be used as normal CppInterOp API functions. To load the API, invoke: ```cpp Cpp::LoadDispatchAPI("path/to/libclangCppInterOp.so"); ``` Now your application can use the CppInterOp API via the `Cpp::` namespace, with all functions being dispatched through the function pointers. This is a one-to-one replacement for linking and using <CppInterOp/CppInterOp.h> directly, with a few drawbacks: - This system currently does not support overloaded public API - The function pointers are not initialized until `LoadDispatchAPI` is called, which means that any attempt to use the API before loading will result in a null pointer dereference. - You lose the ability to assume default arguments in API calls, which must now be provided explicitly since we rely on function pointers.

…te CppInterOpTestsDispatch The unittests now dynamically change behaviours from a standard library usage of CppInterOp to utilising the dispatch mechanism based on the the presence of the `ENABLE_DISPATCH_TESTS` flag

…arguments

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2026 Project Roadmap #782

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aaronj0 added 2 commits January 23, 2026 20:49

Move public API into the CppImpl namespace and conditionally alias to…

0989007

… Cpp

aaronj0 force-pushed the api-dispatch-mechanism branch from 9e1cb56 to 1e5775a Compare January 23, 2026 20:11

aaronj0 mentioned this pull request Jan 23, 2026

Migrate to CppInterOp Dispatch, no longer link/load shared lib in Python compiler-research/cppyy-backend#177

Merged

aaronj0 added 2 commits January 24, 2026 04:45

[test] Refactor typed fixture names and conditionally expand default …

30d5816

…arguments

[docs] Add section explaining how-to-use the Dispatch mechanism

dd612b1

aaronj0 force-pushed the api-dispatch-mechanism branch from 1e5775a to dd612b1 Compare January 24, 2026 03:45

aaronj0 merged commit dea9b71 into compiler-research:main Jan 24, 2026
30 of 67 checks passed

	std::vector<Cpp::TemplateArgInfo> empty_templ_args = {};
	static std::vector<Cpp::TemplateArgInfo> empty_templ_args = {};

	Cpp::GetVariableType(Cpp::GetNamed("a", 0))};
	Cpp::GetVariableType(Cpp::GetNamed("a", nullptr))};

	clang_invoke(S, &object_c, nullptr, 0, 0);
	clang_invoke(S, &object_c, nullptr, 0, nullptr);

	Cpp::MakeFunctionCallable(Cpp::GetNamed("f2", 0));
	Cpp::MakeFunctionCallable(Cpp::GetNamed("f2", nullptr));

	clang::NamedDecl ClassC = (clang::NamedDecl)Cpp::GetNamed("C", 0);
	clang::NamedDecl ClassC = (clang::NamedDecl)Cpp::GetNamed("C", nullptr);

	Cpp::TCppScope_t set_5 = Cpp::GetNamed("set_5", 0);
	Cpp::TCppScope_t set_5 = Cpp::GetNamed("set_5", nullptr);

	Cpp::GetNamed("TypedefToPrivateClass", 0);
	Cpp::GetNamed("TypedefToPrivateClass", nullptr);

	Cpp::TCppScope_t TOperator = Cpp::GetNamed("TOperator", 0);
	Cpp::TCppScope_t TOperator = Cpp::GetNamed("TOperator", nullptr);

	Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1", 0));
	Cpp::TCppType_t K1 = Cpp::GetTypeFromScope(Cpp::GetNamed("K1", nullptr));

	Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2", 0));
	Cpp::TCppType_t K2 = Cpp::GetTypeFromScope(Cpp::GetNamed("K2", nullptr));

	Cpp::GetOperator(Cpp::GetScope("N2", Cpp::GetScope("N1", 0)), Cpp::Operator::OP_Plus,
	Cpp::GetOperator(Cpp::GetScope("N2", Cpp::GetScope("N1", nullptr)), Cpp::Operator::OP_Plus,

	Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std", 0),
	Cpp::GetClassTemplatedMethods("get", Cpp::GetScope("my_std", nullptr),

	Cpp::TCppType_t p = Cpp::GetTypeFromScope(Cpp::GetNamed("p", 0));
	Cpp::TCppType_t p = Cpp::GetTypeFromScope(Cpp::GetNamed("p", nullptr));

	{Cpp::GetVariableType(Cpp::GetNamed("tuple_one", 0)),
	{Cpp::GetVariableType(Cpp::GetNamed("tuple_one", nullptr)),

	Cpp::GetVariableType(Cpp::GetNamed("tuple_two", 0))});
	Cpp::GetVariableType(Cpp::GetNamed("tuple_two", nullptr))});

	Cpp::GetNamed("bar", Cpp::GetScope("EnumFunctionSameName", 0));
	Cpp::GetNamed("bar", Cpp::GetScope("EnumFunctionSameName", nullptr));

	std::cerr << "[CppInterOp] Failed to load critical functions\n";
	std::cerr << "[CppInterOp Dispatch] Failed to load critical functions\n";

	Cpp::TCppScope_t ns_N1 = Cpp::GetNamed("N1", 0);
	Cpp::TCppScope_t ns_N1 = Cpp::GetNamed("N1", DFLT_0);

	auto *VD = Cpp::GetNamed("var", 0);
	auto *VD = Cpp::GetNamed("var", DFLT_0);

	auto* VD1 = Cpp::GetNamed("var1", 0);
	auto* VD1 = Cpp::GetNamed("var1", DFLT_0);

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	/type_size/ args1.size(), false);
	/type_size/ args1.size() DFLT_FALSE);

	/type_size/ args3.size(), false);
	/type_size/ args3.size() DFLT_FALSE);