91cdd35008
This is a major change on how we represent nested name qualifications in the AST. * The nested name specifier itself and how it's stored is changed. The prefixes for types are handled within the type hierarchy, which makes canonicalization for them super cheap, no memory allocation required. Also translating a type into nested name specifier form becomes a no-op. An identifier is stored as a DependentNameType. The nested name specifier gains a lightweight handle class, to be used instead of passing around pointers, which is similar to what is implemented for TemplateName. There is still one free bit available, and this handle can be used within a PointerUnion and PointerIntPair, which should keep bit-packing aficionados happy. * The ElaboratedType node is removed, all type nodes in which it could previously apply to can now store the elaborated keyword and name qualifier, tail allocating when present. * TagTypes can now point to the exact declaration found when producing these, as opposed to the previous situation of there only existing one TagType per entity. This increases the amount of type sugar retained, and can have several applications, for example in tracking module ownership, and other tools which care about source file origins, such as IWYU. These TagTypes are lazily allocated, in order to limit the increase in AST size. This patch offers a great performance benefit. It greatly improves compilation time for [stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for `test_on2.cpp` in that project, which is the slowest compiling test, this patch improves `-c` compilation time by about 7.2%, with the `-fsyntax-only` improvement being at ~12%. This has great results on compile-time-tracker as well:  This patch also further enables other optimziations in the future, and will reduce the performance impact of template specialization resugaring when that lands. It has some other miscelaneous drive-by fixes. About the review: Yes the patch is huge, sorry about that. Part of the reason is that I started by the nested name specifier part, before the ElaboratedType part, but that had a huge performance downside, as ElaboratedType is a big performance hog. I didn't have the steam to go back and change the patch after the fact. There is also a lot of internal API changes, and it made sense to remove ElaboratedType in one go, versus removing it from one type at a time, as that would present much more churn to the users. Also, the nested name specifier having a different API avoids missing changes related to how prefixes work now, which could make existing code compile but not work. How to review: The important changes are all in `clang/include/clang/AST` and `clang/lib/AST`, with also important changes in `clang/lib/Sema/TreeTransform.h`. The rest and bulk of the changes are mostly consequences of the changes in API. PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just for easier to rebasing. I plan to rename it back after this lands. Fixes #136624 Fixes https://github.com/llvm/llvm-project/issues/43179 Fixes https://github.com/llvm/llvm-project/issues/68670 Fixes https://github.com/llvm/llvm-project/issues/92757
271 lines
12 KiB
C++
271 lines
12 KiB
C++
// RUN: %clang_cc1 -std=c++2a -x c++ %s -verify -Wno-unused-value
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template<typename T, typename U>
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constexpr bool is_same_v = false;
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template<typename T>
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constexpr bool is_same_v<T, T> = true;
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// We use a hack in this file to make the compiler print out the requires
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// expression after it has been instantiated - we put false_v<requires {...}> as
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// the requires clause of a class template, then instantiate the template.
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// The requirement will not be satisfied, and the explaining diagnostic will
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// print out false_v<requires {...}> in its raw form (the false_v serves to
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// prevent the diagnostic from elaborating on why the requires expr wasn't
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// satisfied).
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template<bool v>
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constexpr bool false_v = false;
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template<typename... Ts>
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using void_t = void;
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// Check that requires parameters are instantiated correctly.
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template<typename T> requires
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false_v<requires (T t) { requires is_same_v<decltype(t), int>; }>
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// expected-note@-1 {{because 'false_v<requires (int t) { requires is_same_v<decltype(t), int>; }>' evaluated to false}}
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// expected-note@-2 {{because 'false_v<requires (char t) { requires is_same_v<decltype(t), int>; }>' evaluated to false}}
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struct r1 {};
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using r1i1 = r1<int>; // expected-error {{constraints not satisfied for class template 'r1' [with T = int]}}
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using r1i2 = r1<char>; // expected-error {{constraints not satisfied for class template 'r1' [with T = char]}}
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// Check that parameter packs work.
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template<typename... Ts> requires
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false_v<requires (Ts... ts) {requires ((sizeof(ts) == 2) && ...);}>
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// expected-note@-1 {{because 'false_v<requires (short ts, unsigned short ts) { requires (sizeof (ts) == 2) && (sizeof (ts) == 2); }>'}}
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// expected-note@-2 {{because 'false_v<requires (short ts) { requires (sizeof (ts) == 2); }>' evaluated to false}}
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struct r2 {};
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using r2i1 = r2<short, unsigned short>; // expected-error {{constraints not satisfied for class template 'r2' [with Ts = <short, unsigned short>]}}
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using r2i2 = r2<short>; // expected-error {{constraints not satisfied for class template 'r2' [with Ts = <short>]}}
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template<typename... Ts> requires
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false_v<(requires (Ts ts) {requires sizeof(ts) != 0;} && ...)>
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// expected-note@-1 {{because 'false_v<requires (short ts) { requires sizeof (ts) != 0; } && requires (unsigned short ts) { requires sizeof (ts) != 0; }>' evaluated to false}}
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// expected-note@-2 {{because 'false_v<requires (short ts) { requires sizeof (ts) != 0; }>' evaluated to false}}
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struct r3 {};
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using r3i1 = r3<short, unsigned short>; // expected-error {{constraints not satisfied for class template 'r3' [with Ts = <short, unsigned short>]}}
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using r3i2 = r3<short>; // expected-error {{constraints not satisfied for class template 'r3' [with Ts = <short>]}}
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template<typename T>
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struct identity { using type = T; };
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namespace type_requirement {
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struct A {};
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// check that nested name specifier is instantiated correctly.
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template<typename T> requires false_v<requires { typename T::type; }> // expected-note{{because 'false_v<requires { typename identity<int>::type; }>' evaluated to false}}
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struct r1 {};
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using r1i = r1<identity<int>>; // expected-error{{constraints not satisfied for class template 'r1' [with T = identity<int>]}}
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// check that template argument list is instantiated correctly.
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template<typename T>
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struct contains_template {
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template<typename U> requires is_same_v<contains_template<T>, U>
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using temp = int;
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};
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template<typename T> requires
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false_v<requires { typename T::template temp<T>; }>
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// expected-note@-1 {{because 'false_v<requires { typename type_requirement::contains_template<int>::template temp<type_requirement::contains_template<int>>; }>' evaluated to false}}
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// expected-note@-2 {{because 'false_v<requires { typename type_requirement::contains_template<short>::template temp<type_requirement::contains_template<short>>; }>' evaluated to false}}
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struct r2 {};
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using r2i1 = r2<contains_template<int>>; // expected-error{{constraints not satisfied for class template 'r2' [with T = type_requirement::contains_template<int>]}}
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using r2i2 = r2<contains_template<short>>; // expected-error{{constraints not satisfied for class template 'r2' [with T = type_requirement::contains_template<short>]}}
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// substitution error occurs, then requires expr is instantiated again
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template<typename T>
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struct a {
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template<typename U> requires (requires { typename T::a::a; }, false)
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// expected-note@-1{{because 'requires { <<error-type>>; } , false' evaluated to false}}
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struct r {};
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};
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using ari = a<int>::r<short>; // expected-error{{constraints not satisfied for class template 'r' [with U = short]}}
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// Parameter pack inside expr
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template<typename... Ts> requires
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false_v<(requires { typename Ts::type; } && ...)>
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// expected-note@-1 {{because 'false_v<requires { typename identity<short>::type; } && requires { typename identity<int>::type; } && requires { <<error-type>>; }>' evaluated to false}}
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struct r5 {};
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using r5i = r5<identity<short>, identity<int>, short>; // expected-error{{constraints not satisfied for class template 'r5' [with Ts = <identity<short>, identity<int>, short>]}}
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template<typename... Ts> requires
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false_v<(requires { typename void_t<Ts>; } && ...)> // expected-note{{because 'false_v<requires { typename void_t<int>; } && requires { typename void_t<short>; }>' evaluated to false}}
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struct r6 {};
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using r6i = r6<int, short>; // expected-error{{constraints not satisfied for class template 'r6' [with Ts = <int, short>]}}
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template<typename... Ts> requires
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false_v<(requires { typename Ts::template aaa<Ts>; } && ...)>
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// expected-note@-1 {{because 'false_v<requires { <<error-type>>; } && requires { <<error-type>>; }>' evaluated to false}}
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struct r7 {};
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using r7i = r7<int, A>; // expected-error{{constraints not satisfied for class template 'r7' [with Ts = <int, type_requirement::A>]}}
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}
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namespace expr_requirement {
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// check that compound/simple requirements are instantiated correctly.
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template<typename T> requires false_v<requires { sizeof(T); { sizeof(T) }; }>
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// expected-note@-1 {{because 'false_v<requires { sizeof(int); { sizeof(int) }; }>' evaluated to false}}
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// expected-note@-2 {{because 'false_v<requires { <<error-expression>>; { sizeof(T) }; }>' evaluated to false}}
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struct r1 {};
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using r1i1 = r1<int>; // expected-error{{constraints not satisfied for class template 'r1' [with T = int]}}
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using r1i2 = r1<void>; // expected-error{{constraints not satisfied for class template 'r1' [with T = void]}}
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// substitution error occurs in expr, then expr is instantiated again.
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template<typename T>
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struct a {
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template<typename U> requires (requires { sizeof(T::a); }, false) // expected-note{{because 'requires { <<error-expression>>; } , false' evaluated to false}}
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struct r {};
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};
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using ari = a<int>::r<short>; // expected-error{{constraints not satisfied for class template 'r' [with U = short]}}
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// check that the return-type-requirement is instantiated correctly.
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template<typename T, typename U = int>
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concept C1 = is_same_v<T, U>;
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template<typename T> requires false_v<requires(T t) { { t } -> C1<T>; }>
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// expected-note@-1 {{because 'false_v<requires (int t) { { t } -> C1<int>; }>' evaluated to false}}
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// expected-note@-2 {{because 'false_v<requires (double t) { { t } -> C1<double>; }>' evaluated to false}}
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struct r2 {};
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using r2i1 = r2<int>; // expected-error{{constraints not satisfied for class template 'r2' [with T = int]}}
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using r2i2 = r2<double>; // expected-error{{constraints not satisfied for class template 'r2' [with T = double]}}
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// substitution error occurs in return type requirement, then requires expr is
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// instantiated again.
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template<typename T>
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struct b {
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template<typename U> requires (requires { { 0 } -> C1<typename T::a>; }, false) // expected-note{{because 'requires { { 0 } -> <<error-type>>; } , false' evaluated to false}}
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struct r {};
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};
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using bri = b<int>::r<short>; // expected-error{{constraints not satisfied for class template 'r' [with U = short]}}
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template<typename... Ts> requires
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false_v<(requires { { 0 } noexcept -> C1<Ts>; } && ...)>
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// expected-note@-1 {{because 'false_v<requires { { 0 } noexcept -> C1<int>; } && requires { { 0 } noexcept -> C1<unsigned int>; }>' evaluated to false}}
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struct r3 {};
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using r3i = r3<int, unsigned int>; // expected-error{{constraints not satisfied for class template 'r3' [with Ts = <int, unsigned int>]}}
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template<typename T>
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struct r4 {
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constexpr int foo() {
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if constexpr (requires { this->invalid(); })
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return 1;
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else
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return 0;
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}
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constexpr void invalid() requires false { }
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};
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static_assert(r4<int>{}.foo() == 0);
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}
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namespace nested_requirement {
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// check that constraint expression is instantiated correctly
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template<typename T> requires false_v<requires { requires sizeof(T) == 2; }> // expected-note{{because 'false_v<requires { requires sizeof(int) == 2; }>' evaluated to false}}
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struct r1 {};
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using r1i = r1<int>; // expected-error{{constraints not satisfied for class template 'r1' [with T = int]}}
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// substitution error occurs in expr, then expr is instantiated again.
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template<typename T>
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struct a {
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template<typename U> requires
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(requires { requires sizeof(T::a) == 0; }, false) // expected-note{{because 'requires { requires <<error-expression>>; } , false' evaluated to false}}
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struct r {};
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};
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using ari = a<int>::r<short>; // expected-error{{constraints not satisfied for class template 'r' [with U = short]}}
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// Parameter pack inside expr
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template<typename... Ts> requires
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false_v<(requires { requires sizeof(Ts) == 0; } && ...)>
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// expected-note@-1 {{because 'false_v<requires { requires sizeof(int) == 0; } && requires { requires sizeof(short) == 0; }>' evaluated to false}}
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struct r2 {};
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using r2i = r2<int, short>; // expected-error{{constraints not satisfied for class template 'r2' [with Ts = <int, short>]}}
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}
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// Parameter pack inside multiple requirements
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template<typename... Ts> requires
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false_v<(requires { requires sizeof(Ts) == 0; sizeof(Ts); } && ...)>
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// expected-note@-1 {{because 'false_v<requires { requires sizeof(int) == 0; sizeof(Ts); } && requires { requires sizeof(short) == 0; sizeof(Ts); }>' evaluated to false}}
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struct r4 {};
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using r4i = r4<int, short>; // expected-error{{constraints not satisfied for class template 'r4' [with Ts = <int, short>]}}
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template<typename... Ts> requires
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false_v<(requires(Ts t) { requires sizeof(t) == 0; t++; } && ...)>
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// expected-note@-1 {{because 'false_v<requires (int t) { requires sizeof (t) == 0; t++; } && requires (short t) { requires sizeof (t) == 0; t++; }>' evaluated to false}}
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struct r5 {};
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using r5i = r5<int, short>; // expected-error{{constraints not satisfied for class template 'r5' [with Ts = <int, short>]}}
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template<typename T> requires
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false_v<(requires(T t) { T{t}; })> // T{t} creates an "UnevaluatedList" context.
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// expected-note@-1 {{because 'false_v<(requires (int t) { int{t}; })>' evaluated to false}}
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struct r6 {};
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using r6i = r6<int>;
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// expected-error@-1 {{constraints not satisfied for class template 'r6' [with T = int]}}
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namespace GH73885 {
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template <class> // expected-error {{extraneous}}
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template <class T> requires(T{})
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constexpr bool e_v = true;
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static_assert(e_v<bool>);
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} // namespace GH73885
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namespace GH84020 {
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struct B {
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template <typename S> void foo();
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void bar();
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};
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template <typename T, typename S> struct A : T {
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void foo() {
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static_assert(requires { T::template foo<S>(); });
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static_assert(requires { T::bar(); });
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}
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};
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template class A<B, double>;
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} // namespace GH84020
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namespace GH110785 {
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struct Foo {
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static void f(auto) requires(false) {}
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void f(int) {}
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static_assert([](auto v) {
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return requires { f(v); };
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} (0) == false);
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};
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} // namespace GH110785
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