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https://github.com/carbon-language/carbon-lang.git
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Christopher Di Bella
57bf903ef1
`FinishAst` resolves C++ template instantiation. Template instantiation can complete Carbon types, generate thunks, and call generic functions. These operations can add new entries to `definitions_required_by_use()`. Similarly, resolving any of those can generate more C++ templates that need instantiating. This change moves `FinishAst` ahead of `CheckRequiredDefinitions` and loops until no new Carbon definitions have been added. This prevents later passes from crashing when evaluating specifics on unresolved generics or uninstantiated templates. `FinishAst` also disconnects the AST. Subsequent definitions and `impl`s may depend on C++ interop, so the AST must remain connected until all the Carbon end-of-file checks complete. We achieve this by decoupling AST disconnection from finalisation. Assisted-by: Antigravity with Gemini Assisted-by: Antigravity with Claude Opus 5.5 Max
95 lines
2.4 KiB
Plaintext
95 lines
2.4 KiB
Plaintext
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/int.carbon
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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/interop/cpp/template/bidirectional_generic_call.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/template/bidirectional_generic_call.carbon
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// --- member_function_calls_carbon.carbon
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library "[[@TEST_NAME]]";
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// Resolving `Make({} as C)` at the end of the file uses the constructor of
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// `Wrapper(C)`, whose definition is only instantiated after that. The
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// constructor calls back into Carbon, so `C` must still be usable from C++.
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import Cpp inline '''
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template<typename T>
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struct Wrapper {
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Wrapper() { T::Callback(); }
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};
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''';
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class C {
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fn Callback() {}
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}
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fn Make[T: type](unused x: T) {
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var unused w: Cpp.Wrapper(T);
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}
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fn Run() {
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Make({} as C);
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}
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// --- alternating_passes.carbon
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library "[[@TEST_NAME]]";
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// Each step needs the other language to instantiate or resolve something new:
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//
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// 1. `Run` needs the C++ function template `CallCarbonGeneric<Box>`.
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// 2. `CallCarbonGeneric<Box>` needs the Carbon generic
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// `UseCppClassTemplate(Box)`.
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// 3. `UseCppClassTemplate(Box)` needs the C++ class template
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// `UsesCarbonInterface<Box>`.
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// 4. `UsesCarbonInterface<Box>::Get` needs `Box` to implement the Carbon
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// interface `HasValue`, by calling `GetValue(Box)`. This is the base case.
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import Cpp inline '''
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template<typename T>
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struct UsesCarbonInterface {
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static auto Get(const T& t) -> int;
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};
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''';
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interface HasValue {
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fn Value(self) -> i32;
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}
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class Box {
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var n: i32;
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impl as HasValue {
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fn Value(self) -> i32 { return self.n; }
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}
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}
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fn GetValue[T: HasValue](t: T) -> i32 {
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return t.Value();
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}
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fn UseCppClassTemplate[T: type](t: T) -> i32 {
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return Cpp.UsesCarbonInterface(T).Get(t);
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}
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inline Cpp '''
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template<typename T>
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auto UsesCarbonInterface<T>::Get(const T& t) -> int {
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return Carbon::GetValue(t);
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}
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template<typename T>
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auto CallCarbonGeneric(const T& t) -> int {
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return Carbon::UseCppClassTemplate(t);
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}
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''';
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fn Run() -> i32 {
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let b: Box = {.n = 42};
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return Cpp.CallCarbonGeneric(b);
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}
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