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|
// wasm-eh-tests.cc — standalone C++ EH test functions for the gonix WASM host.
//
// No Lix dependency. Compiled to wasm-eh-tests.wasm with Emscripten -fexceptions.
// Each function has the signature:
// extern "C" int32_t eh_test_NAME(char* buf, int32_t max);
// Returns 0 on success (buf may contain a result string for assertion),
// -1 on failure (buf contains a null-terminated error message).
//
// IMPORTANT: every throw must be in a *called* function, not directly in the
// try body. Emscripten only emits invoke_* wrappers for call sites, not for
// inline throws. Each test therefore has a [[noreturn]] helper that does the
// actual throw so the compiler wraps the call in invoke_*.
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <exception>
#include <stdexcept>
// ---------------------------------------------------------------------------
// Type hierarchy
// ---------------------------------------------------------------------------
struct Base : public std::exception
{
const char * what() const noexcept override
{
return "base error";
}
};
struct Derived : public Base
{
const char * what() const noexcept override
{
return "derived error";
}
};
struct Other : public std::exception
{
const char * what() const noexcept override
{
return "other error";
}
};
// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------
static int32_t write_buf(char * buf, int32_t max, const char * msg)
{
int32_t n = static_cast<int32_t>(strlen(msg));
if (n >= max) {
n = max - 1;
}
memcpy(buf, msg, n);
buf[n] = '\0';
return n;
}
// ---------------------------------------------------------------------------
// Throw helpers — each must be in a separate function so Emscripten wraps the
// call site in invoke_*. Mark [[noreturn]] so the compiler knows they throw.
// ---------------------------------------------------------------------------
[[noreturn]]
static void throw_runtime_error(const char * msg)
{
throw std::runtime_error(msg);
}
[[noreturn]]
static void throw_derived()
{
throw Derived();
}
[[noreturn]]
static void throw_runtime_error_rethrow()
{
throw std::runtime_error("rethrown");
}
// rethrow_current() wraps bare `throw;` in a callee so the compiler emits
// invoke_* at the call site in the surrounding catch block.
[[noreturn]]
static void rethrow_current()
{
throw;
}
[[noreturn]]
static void throw_for_exception_ptr()
{
throw std::runtime_error("captured error");
}
[[noreturn]]
static void throw_for_nested()
{
throw std::runtime_error("inner error");
}
[[noreturn]]
static void throw_for_multi()
{
throw Other();
}
[[noreturn]]
static void throw_for_resume()
{
throw std::runtime_error("transient error");
}
// ---------------------------------------------------------------------------
// 1. eh_test_simple — basic throw / catch
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_simple(char * buf, int32_t max)
{
try {
throw_runtime_error("simple error");
} catch (const std::runtime_error & e) {
char tmp[256];
snprintf(tmp, sizeof(tmp), "caught: %s", e.what());
write_buf(buf, max, tmp);
return 0;
}
write_buf(buf, max, "no exception caught");
return -1;
}
// ---------------------------------------------------------------------------
// 2. eh_test_rethrow — throw / catch / throw; / outer catch
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_rethrow(char * buf, int32_t max)
{
try {
try {
throw_runtime_error_rethrow();
} catch (const std::runtime_error &) {
rethrow_current(); // bare throw; in a callee so compiler emits invoke_*
}
} catch (const std::runtime_error & e) {
char tmp[256];
snprintf(tmp, sizeof(tmp), "outer caught: %s", e.what());
write_buf(buf, max, tmp);
return 0;
}
write_buf(buf, max, "no exception caught");
return -1;
}
// ---------------------------------------------------------------------------
// 3. eh_test_catch_hierarchy — throw Derived / catch Base& (__cxa_can_catch)
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_catch_hierarchy(char * buf, int32_t max)
{
try {
throw_derived();
} catch (const Base & e) {
char tmp[256];
snprintf(tmp, sizeof(tmp), "base caught: %s", e.what());
write_buf(buf, max, tmp);
return 0;
}
write_buf(buf, max, "no exception caught");
return -1;
}
// ---------------------------------------------------------------------------
// 4. eh_test_nested_try — nested try blocks; inner catches; outer never fires
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_nested_try(char * buf, int32_t max)
{
bool outer_fired = false;
try {
try {
throw_for_nested();
} catch (const std::runtime_error &) {
write_buf(buf, max, "inner caught");
// handled — do not rethrow
}
} catch (...) {
outer_fired = true;
}
if (outer_fired) {
write_buf(buf, max, "outer fired unexpectedly");
return -1;
}
return 0;
}
// ---------------------------------------------------------------------------
// 5. eh_test_exception_ptr — std::current_exception / std::rethrow_exception
// This is the exact pattern that caused std::terminate in derivation eval.
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_exception_ptr(char * buf, int32_t max)
{
std::exception_ptr captured;
// Capture inside catch
try {
throw_for_exception_ptr();
} catch (...) {
captured = std::current_exception();
}
// Rethrow outside the original catch block
if (captured) {
try {
std::rethrow_exception(captured);
} catch (const std::runtime_error & e) {
char tmp[256];
snprintf(tmp, sizeof(tmp), "rethrown: %s", e.what());
write_buf(buf, max, tmp);
return 0;
}
}
write_buf(buf, max, "exception_ptr was null");
return -1;
}
// ---------------------------------------------------------------------------
// 6. eh_test_dtor_throw — destructor throws while another exception is active.
// std::terminate() is called by the C++ runtime. Our host must not loop.
// ---------------------------------------------------------------------------
struct ThrowingDtor
{
~ThrowingDtor() noexcept(false)
{
throw std::runtime_error("dtor threw");
}
};
[[noreturn]]
static void throw_with_dtor()
{
ThrowingDtor td;
throw std::runtime_error("outer throw");
}
extern "C" int32_t eh_test_dtor_throw(char * buf, int32_t max)
{
try {
throw_with_dtor();
} catch (...) {
}
// Should not reach here — std::terminate fires first.
write_buf(buf, max, "survived (unexpected)");
return -1;
}
// ---------------------------------------------------------------------------
// 7. eh_test_multi_catch — multiple catch clauses; correct one selected
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_multi_catch(char * buf, int32_t max)
{
try {
throw_for_multi();
} catch (const std::runtime_error &) {
write_buf(buf, max, "matched: runtime_error (wrong)");
return -1;
} catch (const Base &) {
write_buf(buf, max, "matched: Base (wrong)");
return -1;
} catch (const Other &) {
write_buf(buf, max, "matched: Other");
return 0;
} catch (...) {
write_buf(buf, max, "matched: catch-all (wrong)");
return -1;
}
write_buf(buf, max, "no exception caught");
return -1;
}
// ---------------------------------------------------------------------------
// 9. eh_test_propagate_through — exception propagates through a frame with no
// catch block. Emscripten emits find_matching_catch_2 + resumeException +
// unreachable in the middle frame. The host's __resumeException must panic
// (never return) for the enclosing invoke_* to catch it and set setThrew.
//
// middle_no_catch: no try/catch — just calls throw_runtime_error.
// Emscripten codegen for middle_no_catch:
// invoke_*(slot_of_throw_runtime_error, "propagated")
// ; if threw:
// call __cxa_find_matching_catch_2() ; no typed clauses
// call __resumeException(thrown) ; re-raises — must never return
// unreachable
// ---------------------------------------------------------------------------
// No catch — exception propagates up through this frame.
// [[noinline]] is critical: without it Emscripten inlines this into the outer
// function and the resumeException+unreachable pattern never appears.
[[gnu::noinline]]
static int32_t middle_no_catch(char * buf, int32_t max)
{
throw_runtime_error("propagated");
write_buf(buf, max, "no throw (unexpected)");
return -1;
}
extern "C" int32_t eh_test_propagate_through(char * buf, int32_t max)
{
try {
middle_no_catch(buf, max);
} catch (const std::runtime_error & e) {
char tmp[256];
snprintf(tmp, sizeof(tmp), "caught after propagate: %s", e.what());
write_buf(buf, max, tmp);
return 0;
}
write_buf(buf, max, "no exception caught");
return -1;
}
// ---------------------------------------------------------------------------
// 10. eh_test_exception_ptr_rethrow_chain — mirrors writeDerivation→blockOn:
// throw → catch(...){capture ptr, end_catch} → rethrow_exception(ptr)
// → caught by outer catch(T&){throw;} → outermost catch gets it.
//
// This is the exact pattern in the real evaluator:
// canonPath throws
// writeDerivation: catch(...) { co_return result::current_exception(); }
// blockOn / Result::value(): std::rethrow_exception(stored_ptr)
// derivationStrictInternal: catch(Error&) { e.addTrace(...); throw; }
// prim_derivationStrict: outermost catch
// ---------------------------------------------------------------------------
static std::exception_ptr capture_and_return()
{
std::exception_ptr p;
try {
throw_runtime_error("propagated");
} catch (...) {
p = std::current_exception();
}
return p;
}
[[noreturn]]
static void rethrow_ptr(std::exception_ptr p)
{
std::rethrow_exception(p);
}
// Middle layer: receives the rethrown exception, adds a modification, rethrows.
// Mirrors derivationStrictInternal's catch(Error&){addTrace;throw;} pattern.
// [[noinline]] prevents the compiler from collapsing the chain.
[[gnu::noinline]]
static void middle_catch_rethrow(char * buf, int32_t max)
{
// capture in inner scope
auto p = capture_and_return();
// rethrow outside original catch — mirrors blockOn/Result::value()
try {
rethrow_ptr(p);
} catch (std::runtime_error & e) {
// add a "trace" by writing to buf, then rethrow — mirrors addTrace+throw
snprintf(buf, max, "traced: %s", e.what());
rethrow_current();
}
}
extern "C" int32_t eh_test_exception_ptr_rethrow_chain(char * buf, int32_t max)
{
try {
middle_catch_rethrow(buf, max);
} catch (const std::runtime_error & e) {
char tmp[256];
snprintf(tmp, sizeof(tmp), "chained: %s", e.what());
write_buf(buf, max, tmp);
return 0;
}
write_buf(buf, max, "no exception caught");
return -1;
}
// ---------------------------------------------------------------------------
// 11. eh_test_uncaught_depth_stable — __cxa_end_catch must not leak
// exceptionLast when there are nested rethrows.
//
// Mirrors the real hang: canonPath throws → writeDerivation catches into
// exception_ptr → rethrow_exception → derivationStrictInternal catch(T&){throw;}
// → prim_derivationStrict catch(T&){throw;} → EvalState::callFunction ...
//
// If __cxa_end_catch unconditionally zeroes g_exceptionLast (the bug),
// subsequent __resumeException / __cxa_rethrow calls re-add entries to
// g_exceptionCaught without the earlier entries ever being cleared,
// growing the catch-stack without bound and looping forever.
//
// A correct implementation completes all 20 iterations and returns "stable".
// The buggy implementation never returns (test fails with 5s timeout).
// ---------------------------------------------------------------------------
// Captures the current exception into an exception_ptr, then returns.
// Mirrors writeDerivation's catch(...){ co_return result::current_exception(); }.
static std::exception_ptr capture_exception()
{
std::exception_ptr p;
try {
throw_runtime_error("propagated");
} catch (...) {
p = std::current_exception();
}
return p;
}
// Rethrows via rethrow_exception, then catches and rethrows bare.
// Mirrors blockOn/Result::value() → derivationStrictInternal catch(T&){throw;}.
// [[noinline]] prevents the compiler from collapsing the chain.
[[gnu::noinline]]
static void rethrow_via_ptr_then_rethrow()
{
auto p = capture_exception();
try {
std::rethrow_exception(p); // __cxa_rethrow_primary_exception
} catch (std::runtime_error &) {
rethrow_current(); // throw; — __cxa_rethrow
}
}
// Outer layer: catches and rethrows again, like prim_derivationStrict.
// [[noinline]] ensures a separate invoke_* frame.
[[gnu::noinline]]
static void outer_catch_rethrow()
{
try {
rethrow_via_ptr_then_rethrow();
} catch (std::runtime_error &) {
rethrow_current();
}
}
extern "C" int32_t eh_test_uncaught_depth_stable(char * buf, int32_t max)
{
for (int i = 0; i < 20; i++) {
try {
outer_catch_rethrow();
} catch (const std::runtime_error &) {
// exception fully handled — catch stack must be empty after this
}
}
write_buf(buf, max, "stable");
return 0;
}
// ---------------------------------------------------------------------------
// 8. eh_test_catch_and_resume — state cleanup between calls
// Call 1: throw flag set → exception handled, return 0
// Call 2: no throw → no exception, return 0
// ---------------------------------------------------------------------------
extern "C" int32_t eh_test_catch_and_resume(char * buf, int32_t max)
{
static int call_count = 0;
int call = ++call_count;
if (call == 1) {
try {
throw_for_resume();
} catch (const std::runtime_error &) {
write_buf(buf, max, "exception handled");
return 0;
}
} else {
write_buf(buf, max, "no exception");
return 0;
}
return -1;
}
|