This revision was landed with ongoing or failed builds. This revision was automatically updated to reflect the committed changes. Closed by commit rGe7eec3824656: [clang] Skip re-building lambda expressions in parameters to consteval fns. (authored by usaxena95).
Changed prior to commit: https://reviews.llvm.org/D132945?vs=457546&id=457555#toc Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D132945/new/ https://reviews.llvm.org/D132945 Files: clang/docs/ReleaseNotes.rst clang/lib/Sema/SemaExpr.cpp clang/test/SemaCXX/cxx2a-consteval.cpp
Index: clang/test/SemaCXX/cxx2a-consteval.cpp =================================================================== --- clang/test/SemaCXX/cxx2a-consteval.cpp +++ clang/test/SemaCXX/cxx2a-consteval.cpp @@ -939,3 +939,82 @@ static_assert(max(1,2)==2); static_assert(mid(1,2,3)==2); } // namespace GH51182 + +// https://github.com/llvm/llvm-project/issues/56183 +namespace GH56183 { +consteval auto Foo(auto c) { return c; } +consteval auto Bar(auto f) { return f(); } +void test() { + constexpr auto x = Foo(Bar([] { return 'a'; })); + static_assert(x == 'a'); +} +} // namespace GH56183 + +// https://github.com/llvm/llvm-project/issues/51695 +namespace GH51695 { +// Original ======================================== +template <typename T> +struct type_t {}; + +template <typename...> +struct list_t {}; + +template <typename T, typename... Ts> +consteval auto pop_front(list_t<T, Ts...>) -> auto { + return list_t<Ts...>{}; +} + +template <typename... Ts, typename F> +consteval auto apply(list_t<Ts...>, F fn) -> auto { + return fn(type_t<Ts>{}...); +} + +void test1() { + constexpr auto x = apply(pop_front(list_t<char, char>{}), + []<typename... Us>(type_t<Us>...) { return 42; }); + static_assert(x == 42); +} +// Reduced 1 ======================================== +consteval bool zero() { return false; } + +template <typename F> +consteval bool foo(bool, F f) { + return f(); +} + +void test2() { + constexpr auto x = foo(zero(), []() { return true; }); + static_assert(x); +} + +// Reduced 2 ======================================== +template <typename F> +consteval auto bar(F f) { return f;} + +void test3() { + constexpr auto t1 = bar(bar(bar(bar([]() { return true; }))))(); + static_assert(t1); + + int a = 1; // expected-note {{declared here}} + auto t2 = bar(bar(bar(bar([=]() { return a; }))))(); // expected-error-re {{call to consteval function 'GH51695::bar<(lambda at {{.*}})>' is not a constant expression}} + // expected-note@-1 {{read of non-const variable 'a' is not allowed in a constant expression}} + + constexpr auto t3 = bar(bar([x=bar(42)]() { return x; }))(); + static_assert(t3==42); + constexpr auto t4 = bar(bar([x=bar(42)]() consteval { return x; }))(); + static_assert(t4==42); +} + +} // namespace GH51695 + +// https://github.com/llvm/llvm-project/issues/50455 +namespace GH50455 { +void f() { + []() consteval { int i{}; }(); + []() consteval { int i{}; ++i; }(); +} +void g() { + (void)[](int i) consteval { return i; }(0); + (void)[](int i) consteval { return i; }(0); +} +} // namespace GH50455 Index: clang/lib/Sema/SemaExpr.cpp =================================================================== --- clang/lib/Sema/SemaExpr.cpp +++ clang/lib/Sema/SemaExpr.cpp @@ -17598,6 +17598,11 @@ DRSet.erase(E); return E; } + ExprResult TransformLambdaExpr(LambdaExpr *E) { + // Do not rebuild lambdas to avoid creating a new type. + // Lambdas have already been processed inside their eval context. + return E; + } bool AlwaysRebuild() { return false; } bool ReplacingOriginal() { return true; } bool AllowSkippingCXXConstructExpr() { Index: clang/docs/ReleaseNotes.rst =================================================================== --- clang/docs/ReleaseNotes.rst +++ clang/docs/ReleaseNotes.rst @@ -211,9 +211,16 @@ - Correctly set expression evaluation context as 'immediate function context' in consteval functions. This fixes `GH51182 <https://github.com/llvm/llvm-project/issues/51182>` + - Fixes an assert crash caused by looking up missing vtable information on ``consteval`` virtual functions. Fixes `GH55065 <https://github.com/llvm/llvm-project/issues/55065>`_. +- Skip rebuilding lambda expressions in arguments of immediate invocations. + This fixes `GH56183 <https://github.com/llvm/llvm-project/issues/56183>`_, + `GH51695 <https://github.com/llvm/llvm-project/issues/51695>`_, + `GH50455 <https://github.com/llvm/llvm-project/issues/50455>`_, + `GH54872 <https://github.com/llvm/llvm-project/issues/54872>`_, + `GH54587 <https://github.com/llvm/llvm-project/issues/54587>`_. C++2b Feature Support ^^^^^^^^^^^^^^^^^^^^^
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