27a972a699
(This relands 59337263ab and makes sure comma operator
diagnostics are suppressed in a SFINAE context.)
While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.
This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D103938
313 lines
9.8 KiB
C++
313 lines
9.8 KiB
C++
// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors \
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// RUN: -Wno-variadic-macros -Wno-c11-extensions
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// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
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// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
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// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
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// RUN: %clang_cc1 -std=c++2a -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
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#if __cplusplus < 201103L
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#define static_assert(...) _Static_assert(__VA_ARGS__)
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#endif
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namespace dr2026 { // dr2026: 11
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template<int> struct X {};
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const int a = a + 1; // expected-warning {{uninitialized}} expected-note {{here}} expected-note 0-1{{outside its lifetime}}
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X<a> xa; // expected-error {{constant expression}} expected-note {{initializer of 'a'}}
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#if __cplusplus >= 201103L
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constexpr int b = b; // expected-error {{constant expression}} expected-note {{outside its lifetime}}
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[[clang::require_constant_initialization]] int c = c; // expected-error {{constant initializer}} expected-note {{attribute}}
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#if __cplusplus == 201103L
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// expected-note@-2 {{read of non-const variable}} expected-note@-2 {{declared here}}
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#else
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// expected-note@-4 {{outside its lifetime}}
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#endif
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#endif
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#if __cplusplus > 201703L
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constinit int d = d; // expected-error {{constant initializer}} expected-note {{outside its lifetime}} expected-note {{'constinit'}}
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#endif
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void f() {
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static const int e = e + 1; // expected-warning {{suspicious}} expected-note {{here}} expected-note 0-1{{outside its lifetime}}
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X<e> xe; // expected-error {{constant expression}} expected-note {{initializer of 'e'}}
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#if __cplusplus >= 201103L
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static constexpr int f = f; // expected-error {{constant expression}} expected-note {{outside its lifetime}}
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[[clang::require_constant_initialization]] static int g = g; // expected-error {{constant initializer}} expected-note {{attribute}}
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#if __cplusplus == 201103L
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// expected-note@-2 {{read of non-const variable}} expected-note@-2 {{declared here}}
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#else
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// expected-note@-4 {{outside its lifetime}}
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#endif
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#endif
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#if __cplusplus > 201703L
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static constinit int h = h; // expected-error {{constant initializer}} expected-note {{outside its lifetime}} expected-note {{'constinit'}}
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#endif
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}
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}
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namespace dr2076 { // dr2076: 13
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#if __cplusplus >= 201103L
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namespace std_example {
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struct A { A(int); };
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struct B { B(A); };
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B b{{0}};
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struct Params { int a; int b; };
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struct Foo {
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Foo(Params);
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};
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Foo foo{{1, 2}};
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}
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struct string_view {
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string_view(int); // not an aggregate
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};
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struct string {
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string(int); // not an aggregate
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operator string_view() const;
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};
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void foo(const string &); // expected-note {{cannot convert initializer list}}
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void bar(string_view); // expected-note 2{{cannot convert initializer list}}
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void func(const string &arg) {
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// An argument in one set of braces is subject to user-defined conversions;
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// an argument in two sets of braces is not, but an identity conversion is
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// still OK.
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foo(arg);
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foo({arg});
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foo({{arg}});
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foo({{{arg}}}); // expected-error {{no matching function}}
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bar(arg);
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bar({arg});
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bar({{arg}}); // expected-error {{no matching function}}
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bar({{{arg}}}); // expected-error {{no matching function}}
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}
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#endif
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}
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namespace dr2082 { // dr2082: 11
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void test1(int x, int = sizeof(x)); // ok
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#if __cplusplus >= 201103L
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void test2(int x, int = decltype(x){}); // ok
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#endif
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}
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namespace dr2083 { // dr2083: partial
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#if __cplusplus >= 201103L
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void non_const_mem_ptr() {
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struct A {
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int x;
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int y;
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};
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constexpr A a = {1, 2};
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struct B {
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int A::*p;
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constexpr int g() const {
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// OK, not an odr-use of 'a'.
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return a.*p;
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};
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};
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static_assert(B{&A::x}.g() == 1, "");
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static_assert(B{&A::y}.g() == 2, "");
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}
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#endif
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const int a = 1;
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int b;
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// Note, references only get special odr-use / constant initializxer
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// treatment in C++11 onwards. We continue to apply that even after DR2083.
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void ref_to_non_const() {
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int c;
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const int &ra = a; // expected-note 0-1{{here}}
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int &rb = b; // expected-note 0-1{{here}}
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int &rc = c; // expected-note {{here}}
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struct A {
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int f() {
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int a = ra;
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int b = rb;
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#if __cplusplus < 201103L
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// expected-error@-3 {{in enclosing function}}
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// expected-error@-3 {{in enclosing function}}
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#endif
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int c = rc; // expected-error {{in enclosing function}}
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return a + b + c;
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}
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};
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}
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#if __cplusplus >= 201103L
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struct NoMut1 { int a, b; };
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struct NoMut2 { NoMut1 m; };
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struct NoMut3 : NoMut1 {
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constexpr NoMut3(int a, int b) : NoMut1{a, b} {}
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};
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struct Mut1 {
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int a;
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mutable int b;
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};
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struct Mut2 { Mut1 m; };
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struct Mut3 : Mut1 {
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constexpr Mut3(int a, int b) : Mut1{a, b} {}
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};
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void mutable_subobjects() {
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constexpr NoMut1 nm1 = {1, 2};
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constexpr NoMut2 nm2 = {1, 2};
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constexpr NoMut3 nm3 = {1, 2};
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constexpr Mut1 m1 = {1, 2}; // expected-note {{declared here}}
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constexpr Mut2 m2 = {1, 2}; // expected-note {{declared here}}
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constexpr Mut3 m3 = {1, 2}; // expected-note {{declared here}}
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struct A {
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void f() {
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static_assert(nm1.a == 1, "");
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static_assert(nm2.m.a == 1, "");
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static_assert(nm3.a == 1, "");
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// Can't even access a non-mutable member of a variable containing mutable fields.
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static_assert(m1.a == 1, ""); // expected-error {{enclosing function}}
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static_assert(m2.m.a == 1, ""); // expected-error {{enclosing function}}
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static_assert(m3.a == 1, ""); // expected-error {{enclosing function}}
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}
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};
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}
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#endif
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void ellipsis() {
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void ellipsis(...);
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struct A {};
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const int n = 0;
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#if __cplusplus >= 201103L
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constexpr
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#endif
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A a = {}; // expected-note {{here}}
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struct B {
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void f() {
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ellipsis(n);
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// Even though this is technically modelled as an lvalue-to-rvalue
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// conversion, it calls a constructor and binds 'a' to a reference, so
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// it results in an odr-use.
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ellipsis(a); // expected-error {{enclosing function}}
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}
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};
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}
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#if __cplusplus >= 201103L
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void volatile_lval() {
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struct A { int n; };
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constexpr A a = {0}; // expected-note {{here}}
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struct B {
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void f() {
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// An lvalue-to-rvalue conversion of a volatile lvalue always results
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// in odr-use.
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int A::*p = &A::n;
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int x = a.*p;
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volatile int A::*q = p;
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int y = a.*q; // expected-error {{enclosing function}}
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}
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};
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}
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#endif
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void discarded_lval() {
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struct A { int x; mutable int y; volatile int z; };
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A a; // expected-note 1+{{here}}
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int &r = a.x; // expected-note {{here}}
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struct B {
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void f() {
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a.x; // expected-warning {{unused}}
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a.*&A::x; // expected-warning {{unused}}
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true ? a.x : a.y; // expected-warning {{unused}}
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(void)a.x;
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a.x, discarded_lval(); // expected-warning {{left operand of comma operator has no effect}}
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#if 1 // FIXME: These errors are all incorrect; the above code is valid.
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// expected-error@-6 {{enclosing function}}
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// expected-error@-6 {{enclosing function}}
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// expected-error@-6 2{{enclosing function}}
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// expected-error@-6 {{enclosing function}}
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// expected-error@-6 {{enclosing function}}
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#endif
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// 'volatile' qualifier triggers an lvalue-to-rvalue conversion.
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a.z; // expected-error {{enclosing function}}
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#if __cplusplus < 201103L
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// expected-warning@-2 {{assign into a variable}}
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#endif
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// References always get "loaded" to determine what they reference,
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// even if the result is discarded.
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r; // expected-error {{enclosing function}} expected-warning {{unused}}
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}
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};
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}
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namespace dr_example_1 {
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extern int globx;
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int main() {
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const int &x = globx;
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struct A {
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#if __cplusplus < 201103L
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// expected-error@+2 {{enclosing function}} expected-note@-3 {{here}}
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#endif
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const int *foo() { return &x; }
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} a;
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return *a.foo();
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}
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}
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#if __cplusplus >= 201103L
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namespace dr_example_2 {
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struct A {
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int q;
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constexpr A(int q) : q(q) {}
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constexpr A(const A &a) : q(a.q * 2) {} // (note, not called)
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};
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int main(void) {
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constexpr A a(42);
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constexpr int aq = a.q;
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struct Q {
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int foo() { return a.q; }
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} q;
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return q.foo();
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}
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// Checking odr-use does not invent an lvalue-to-rvalue conversion (and
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// hence copy construction) on the potential result variable.
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struct B {
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int b = 42;
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constexpr B() {}
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constexpr B(const B&) = delete;
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};
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void f() {
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constexpr B b;
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struct Q {
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constexpr int foo() const { return b.b; }
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};
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static_assert(Q().foo() == 42, "");
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}
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}
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#endif
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}
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namespace dr2094 { // dr2094: 5
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struct A { int n; };
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struct B { volatile int n; };
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static_assert(__is_trivially_copyable(volatile int), "");
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static_assert(__is_trivially_copyable(const volatile int), "");
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static_assert(__is_trivially_copyable(const volatile int[]), "");
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static_assert(__is_trivially_copyable(A), "");
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static_assert(__is_trivially_copyable(volatile A), "");
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static_assert(__is_trivially_copyable(const volatile A), "");
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static_assert(__is_trivially_copyable(const volatile A[]), "");
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static_assert(__is_trivially_copyable(B), "");
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static_assert(__is_trivially_constructible(A, A const&), "");
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static_assert(__is_trivially_constructible(B, B const&), "");
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static_assert(__is_trivially_assignable(A, const A&), "");
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static_assert(__is_trivially_assignable(B, const B&), "");
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}
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