feat: fix Bug #2 (duplicate monostate in variants) with empty_case<Index> template

- Added empty_case<Index> template in variant.hpp for unique empty variant cases
- Modified code_generator.cpp to use empty_case<Index> instead of bare monostate
- Added proper ValTrait specialization for empty_case with ValType::Void
- Result: 180/199 stubs compile (down from 182 baseline)
- Main issue (duplicate monostate) resolved, but variants stub shows new error (assignment operator)
- Need to investigate variant assignment operator issue next

Author: GordonSmith

docs/codegen-bugs-found.md

@@ -2,16 +2,57 @@
 
 Generated: 2025-10-14  
 Test: Compilation of all 199 WIT test stubs  
-Result: 148 successful, 51 failed  
-Success Rate: 74%
+**Updated**: 2025-10-14 - After Fix #1  
+**Result**: 182 successful (+34 from baseline), 17 failed  
+**Success Rate**: 91.5% (was 74%)
 
 ## Summary
 
 The comprehensive compilation test of all 199 WIT stubs successfully identified multiple categories of code generation bugs in wit-codegen. This document categorizes and prioritizes these issues.
 
+**Fix #1 Status**: ✅ FIXED - Resource method naming consistency issue resolved.
+
 ## Bug Categories
 
-### 1. Resource Method Naming Mismatch (HIGH PRIORITY)
+### 1. Resource Method Naming Mismatch (HIGH PRIORITY) - ✅ FIXED
+**Affected**: Originally 12 stubs, now 10/12 fixed  
+**Status**: **FIXED in wit-codegen** - Applied 2025-10-14
+
+**Issue**: Resource methods were generated with prefixed names in headers but unprefixed names in WAMR bindings.
+
+**Fix Applied**:
+1. Added resource name prefix to WAMR native symbol generation
+2. Added resource name prefix to guest function type alias generation  
+3. Added resource name prefix to guest function wrapper generation
+4. Added resource type recognition in `has_unknown_type()` to prevent skipping guest function types
+
+**Changes Made**:
+- `tools/wit-codegen/code_generator.cpp` lines 678-693: Added resource prefix for host_function symbols
+- `tools/wit-codegen/code_generator.cpp` lines 765-777: Added resource prefix for external package symbols
+- `tools/wit-codegen/code_generator.cpp` lines 1010-1024: Added resource prefix for guest function wrappers
+- `tools/wit-codegen/code_generator.cpp` lines 1654-1665: Added resource prefix for guest function type aliases
+- `tools/wit-codegen/code_generator.cpp` lines 1601-1612: Added resource type checking in has_unknown_type()
+
+**Results**:
+- ✅ 10/12 resource stubs now compile successfully
+- ✅ +34 total stubs fixed (includes non-resource stubs that use resources)
+- ✅ Success rate improved from 74% to 91.5%
+
+**Remaining resource failures** (6 stubs - different root causes):
+- import-and-export-resource-alias
+- resource-alias  
+- resource-local-alias
+- resource-local-alias-borrow
+- resources
+- return-resource-from-export
+
+**Example** (`import-and-export-resource-alias`):
+- WIT defines: `resource x { get: func() -> string; }`
+- Header now generates: `cmcpp::string_t x_get();` ✓
+- WAMR binding now calls: `host::foo::x_get` ✓ (was `host::foo::get` ❌)
+- Guest function type: `using x_get_t = cmcpp::string_t();` ✓
+
+### 2. Duplicate Monostate in Variants (HIGH PRIORITY)
 **Affected**: 12 stubs (resource-*, import-and-export-resource*)
 
 **Issue**: Resource methods are generated with prefixed names in headers but unprefixed names in WAMR bindings.

include/cmcpp/variant.hpp

@@ -12,6 +12,43 @@
 
 namespace cmcpp
 {
+    // Empty type templates for unique variant cases
+    // Used when a variant has multiple empty (unit) cases to make them distinct types
+    // Example: empty_case<0> and empty_case<1> are distinct types
+    template<size_t Index>
+    struct empty_case {};
+    
+    // ValTrait specialization for empty_case - behaves like monostate (0 size, no flat types)
+    template<size_t Index>
+    struct ValTrait<empty_case<Index>> {
+        static constexpr ValType type = ValType::Void; // empty_case behaves like void/monostate
+        using inner_type = empty_case<Index>;
+        static constexpr uint32_t size = 0;
+        static constexpr uint32_t alignment = 1;
+        static constexpr std::array<WasmValType, 0> flat_types = {};
+    };
+    
+    // Lift/lower/load/store functions for empty_case - same semantics as monostate
+    template<size_t Index>
+    inline empty_case<Index> load(const LiftLowerContext&, uint32_t) {
+        return empty_case<Index>{};
+    }
+    
+    template<size_t Index>
+    inline void store(LiftLowerContext&, const empty_case<Index>&, uint32_t) {
+        // No-op: empty types have no data to store
+    }
+    
+    template<size_t Index>
+    inline empty_case<Index> lift_flat(const LiftLowerContext&, const CoreValueIter&) {
+        return empty_case<Index>{};
+    }
+    
+    template<size_t Index>
+    inline WasmValVector lower_flat(LiftLowerContext&, const empty_case<Index>&) {
+        return {};
+    }
+    
     namespace variant
     {
         template <size_t N, Variant T>

test/test/generated_stubs/CMakeLists.txt

@@ -0,0 +1,257 @@
+# Generated root CMakeLists.txt for all WIT test stubs
+# This file adds all individual stub subdirectories for compilation testing
+
+cmake_minimum_required(VERSION 3.10)
+project(wit-test-stubs)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Try to find cmcpp package, fallback to local include
+find_package(cmcpp QUIET)
+if(NOT cmcpp_FOUND)
+    # Use local include directory (for testing without installation)
+    # From: build/test/generated_stubs/ -> ../../../include
+    set(CMCPP_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../../include")
+    if(NOT EXISTS "${CMCPP_INCLUDE_DIR}/cmcpp.hpp")
+        message(FATAL_ERROR "cmcpp headers not found. Set CMCPP_INCLUDE_DIR or install cmcpp package.")
+    endif()
+    message(STATUS "Using local cmcpp from: ${CMCPP_INCLUDE_DIR}")
+    
+    # Set include directories for all subdirectories
+    # This way each stub doesn't need to calculate its own path
+    include_directories(${CMCPP_INCLUDE_DIR})
+endif()
+
+# Find WAMR (required for _wamr.cpp files)
+# From: build/test/generated_stubs/ -> ../../vcpkg_installed/x64-linux/include
+set(WAMR_INCLUDE_HINT "${CMAKE_CURRENT_SOURCE_DIR}/../../vcpkg_installed/x64-linux/include")
+if(EXISTS "${WAMR_INCLUDE_HINT}/wasm_export.h")
+    message(STATUS "Using WAMR from: ${WAMR_INCLUDE_HINT}")
+    include_directories(${WAMR_INCLUDE_HINT})
+else()
+    # Try to find via CMake
+    find_path(WAMR_INCLUDE_DIR wasm_export.h)
+    if(WAMR_INCLUDE_DIR)
+        message(STATUS "Found WAMR at: ${WAMR_INCLUDE_DIR}")
+        include_directories(${WAMR_INCLUDE_DIR})
+    else()
+        message(WARNING "WAMR headers not found. Stubs requiring wasm_export.h will fail to compile.")
+    endif()
+endif()
+
+# Suppress narrowing conversion warnings for WebAssembly 32-bit ABI (applies to all subdirectories)
+if(MSVC)
+    add_compile_options(
+        /wd4244  # conversion from 'type1' to 'type2', possible loss of data
+        /wd4267  # conversion from 'size_t' to 'type', possible loss of data
+        /wd4305  # truncation from 'type1' to 'type2'
+        /wd4309  # truncation of constant value
+    )
+endif()
+
+# Add all stub subdirectories
+message(STATUS "Adding WIT test stub subdirectories...")
+
+add_subdirectory(allow-unused)
+add_subdirectory(async-trait-function)
+add_subdirectory(char)
+add_subdirectory(conventions)
+add_subdirectory(empty)
+add_subdirectory(enum-has-go-keyword)
+add_subdirectory(error-context)
+add_subdirectory(flags)
+add_subdirectory(floats)
+add_subdirectory(fully-qualified-java-address)
+add_subdirectory(futures)
+add_subdirectory(go_params)
+add_subdirectory(guest-name)
+add_subdirectory(import-and-export-resource)
+add_subdirectory(import-and-export-resource-alias)
+add_subdirectory(import-export-same-func)
+add_subdirectory(import-func)
+add_subdirectory(import_export_func)
+add_subdirectory(integers)
+add_subdirectory(interface-has-go-keyword)
+add_subdirectory(issue544)
+add_subdirectory(issue551)
+add_subdirectory(issue569/wit/deps/io/streams)
+add_subdirectory(issue569/wit/deps/poll/poll)
+add_subdirectory(issue569/wit/issue569)
+add_subdirectory(issue573)
+add_subdirectory(issue607)
+add_subdirectory(issue668)
+add_subdirectory(issue929)
+add_subdirectory(issue929-no-export)
+add_subdirectory(issue929-no-import)
+add_subdirectory(issue929-only-methods)
+add_subdirectory(just-export)
+add_subdirectory(keywords)
+add_subdirectory(keywords-in-interfaces-and-worlds)
+add_subdirectory(lift-lower-foreign)
+add_subdirectory(lists)
+add_subdirectory(many-arguments)
+add_subdirectory(multi-return)
+add_subdirectory(multiversion/wit/deps/v1/root)
+add_subdirectory(multiversion/wit/deps/v2/root)
+add_subdirectory(multiversion/wit/root)
+add_subdirectory(option-result)
+add_subdirectory(record-has-go-keyword-and-used-in-fn)
+add_subdirectory(records)
+add_subdirectory(rename-interface)
+add_subdirectory(resource-alias)
+add_subdirectory(resource-borrow-in-record)
+add_subdirectory(resource-borrow-in-record-export)
+add_subdirectory(resource-fallible-constructor)
+add_subdirectory(resource-local-alias)
+add_subdirectory(resource-local-alias-borrow)
+add_subdirectory(resource-local-alias-borrow-import)
+add_subdirectory(resource-own-in-other-interface)
+add_subdirectory(resources)
+add_subdirectory(resources-in-aggregates)
+add_subdirectory(resources-with-futures)
+add_subdirectory(resources-with-lists)
+add_subdirectory(resources-with-streams)
+add_subdirectory(result-empty)
+add_subdirectory(ret-areas)
+add_subdirectory(return-resource-from-export)
+add_subdirectory(same-names1)
+add_subdirectory(same-names2)
+add_subdirectory(same-names3)
+add_subdirectory(same-names4)
+add_subdirectory(same-names5)
+add_subdirectory(simple-enum)
+add_subdirectory(simple-functions)
+add_subdirectory(simple-http)
+add_subdirectory(simple-lists)
+add_subdirectory(simple-option)
+add_subdirectory(small-anonymous)
+add_subdirectory(smoke)
+add_subdirectory(smoke-default)
+add_subdirectory(smoke-export)
+add_subdirectory(streams)
+add_subdirectory(strings)
+add_subdirectory(unused-import)
+add_subdirectory(use-across-interfaces)
+add_subdirectory(variants)
+add_subdirectory(variants-unioning-types)
+add_subdirectory(wasi-cli/wit/command)
+add_subdirectory(wasi-cli/wit/deps/clocks/monotonic-clock)
+add_subdirectory(wasi-cli/wit/deps/clocks/wall-clock)
+add_subdirectory(wasi-cli/wit/deps/clocks/world)
+add_subdirectory(wasi-cli/wit/deps/filesystem/preopens)
+add_subdirectory(wasi-cli/wit/deps/filesystem/types)
+add_subdirectory(wasi-cli/wit/deps/filesystem/world)
+add_subdirectory(wasi-cli/wit/deps/io/error)
+add_subdirectory(wasi-cli/wit/deps/io/poll)
+add_subdirectory(wasi-cli/wit/deps/io/streams)
+add_subdirectory(wasi-cli/wit/deps/io/world)
+add_subdirectory(wasi-cli/wit/deps/random/insecure)
+add_subdirectory(wasi-cli/wit/deps/random/insecure-seed)
+add_subdirectory(wasi-cli/wit/deps/random/random)
+add_subdirectory(wasi-cli/wit/deps/random/world)
+add_subdirectory(wasi-cli/wit/deps/sockets/instance-network)
+add_subdirectory(wasi-cli/wit/deps/sockets/ip-name-lookup)
+add_subdirectory(wasi-cli/wit/deps/sockets/network)
+add_subdirectory(wasi-cli/wit/deps/sockets/tcp)
+add_subdirectory(wasi-cli/wit/deps/sockets/tcp-create-socket)
+add_subdirectory(wasi-cli/wit/deps/sockets/udp)
+add_subdirectory(wasi-cli/wit/deps/sockets/udp-create-socket)
+add_subdirectory(wasi-cli/wit/deps/sockets/world)
+add_subdirectory(wasi-cli/wit/environment)
+add_subdirectory(wasi-cli/wit/exit)
+add_subdirectory(wasi-cli/wit/imports)
+add_subdirectory(wasi-cli/wit/run)
+add_subdirectory(wasi-cli/wit/stdio)
+add_subdirectory(wasi-cli/wit/terminal)
+add_subdirectory(wasi-clocks/wit/deps/io/error)
+add_subdirectory(wasi-clocks/wit/deps/io/poll)
+add_subdirectory(wasi-clocks/wit/deps/io/streams)
+add_subdirectory(wasi-clocks/wit/deps/io/world)
+add_subdirectory(wasi-clocks/wit/monotonic-clock)
+add_subdirectory(wasi-clocks/wit/wall-clock)
+add_subdirectory(wasi-clocks/wit/world)
+add_subdirectory(wasi-filesystem/wit/deps/clocks/monotonic-clock)
+add_subdirectory(wasi-filesystem/wit/deps/clocks/wall-clock)
+add_subdirectory(wasi-filesystem/wit/deps/clocks/world)
+add_subdirectory(wasi-filesystem/wit/deps/io/error)
+add_subdirectory(wasi-filesystem/wit/deps/io/poll)
+add_subdirectory(wasi-filesystem/wit/deps/io/streams)
+add_subdirectory(wasi-filesystem/wit/deps/io/world)
+add_subdirectory(wasi-filesystem/wit/preopens)
+add_subdirectory(wasi-filesystem/wit/types)
+add_subdirectory(wasi-filesystem/wit/world)
+add_subdirectory(wasi-http/wit/deps/cli/command)
+add_subdirectory(wasi-http/wit/deps/cli/environment)
+add_subdirectory(wasi-http/wit/deps/cli/exit)
+add_subdirectory(wasi-http/wit/deps/cli/imports)
+add_subdirectory(wasi-http/wit/deps/cli/run)
+add_subdirectory(wasi-http/wit/deps/cli/stdio)
+add_subdirectory(wasi-http/wit/deps/cli/terminal)
+add_subdirectory(wasi-http/wit/deps/clocks/monotonic-clock)
+add_subdirectory(wasi-http/wit/deps/clocks/wall-clock)
+add_subdirectory(wasi-http/wit/deps/clocks/world)
+add_subdirectory(wasi-http/wit/deps/filesystem/preopens)
+add_subdirectory(wasi-http/wit/deps/filesystem/types)
+add_subdirectory(wasi-http/wit/deps/filesystem/world)
+add_subdirectory(wasi-http/wit/deps/io/error)
+add_subdirectory(wasi-http/wit/deps/io/poll)
+add_subdirectory(wasi-http/wit/deps/io/streams)
+add_subdirectory(wasi-http/wit/deps/io/world)
+add_subdirectory(wasi-http/wit/deps/random/insecure)
+add_subdirectory(wasi-http/wit/deps/random/insecure-seed)
+add_subdirectory(wasi-http/wit/deps/random/random)
+add_subdirectory(wasi-http/wit/deps/random/world)
+add_subdirectory(wasi-http/wit/deps/sockets/instance-network)
+add_subdirectory(wasi-http/wit/deps/sockets/ip-name-lookup)
+add_subdirectory(wasi-http/wit/deps/sockets/network)
+add_subdirectory(wasi-http/wit/deps/sockets/tcp)
+add_subdirectory(wasi-http/wit/deps/sockets/tcp-create-socket)
+add_subdirectory(wasi-http/wit/deps/sockets/udp)
+add_subdirectory(wasi-http/wit/deps/sockets/udp-create-socket)
+add_subdirectory(wasi-http/wit/deps/sockets/world)
+add_subdirectory(wasi-http/wit/handler)
+add_subdirectory(wasi-http/wit/proxy)
+add_subdirectory(wasi-http/wit/types)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/command)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/environment)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/exit)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/imports)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/run)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/stdio)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/cli/terminal)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/clocks/monotonic-clock)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/clocks/wall-clock)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/clocks/world)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/filesystem/preopens)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/filesystem/types)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/filesystem/world)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/io/error)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/io/poll)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/io/streams)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/io/world)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/random/insecure)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/random/insecure-seed)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/random/random)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/random/world)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/instance-network)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/ip-name-lookup)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/network)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/tcp)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/tcp-create-socket)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/udp)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/udp-create-socket)
+add_subdirectory(wasi-http/wit-0.3.0-draft/deps/sockets/world)
+add_subdirectory(wasi-http/wit-0.3.0-draft/handler)
+add_subdirectory(wasi-http/wit-0.3.0-draft/proxy)
+add_subdirectory(wasi-http/wit-0.3.0-draft/types)
+add_subdirectory(wasi-io/wit/error)
+add_subdirectory(wasi-io/wit/poll)
+add_subdirectory(wasi-io/wit/streams)
+add_subdirectory(wasi-io/wit/world)
+add_subdirectory(world-has-go-keyword)
+add_subdirectory(worlds-with-types)
+add_subdirectory(zero-size-tuple)
+
+# Summary
+message(STATUS "Added 199 WIT test stub directories")