forked from OSchip/llvm-project
122 lines
5.1 KiB
C++
122 lines
5.1 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify %s
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// RUN: %clang_cc1 -fsyntax-only -std=c++1z -verify %s
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// A converted constant expression of type T is a core constant expression,
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int nonconst = 8; // expected-note 3 {{here}}
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enum NonConstE : unsigned char { NCE = nonconst }; // expected-error {{enumerator value is not a constant expression}} expected-note {{read of non-const}}
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template<int = nonconst> struct NonConstT {}; // expected-error {{non-type template argument is not a constant expression}} expected-note {{read of non-const}}
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void NonConstF() {
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switch (nonconst) {
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case nonconst: // expected-error {{case value is not a constant expression}} expected-note {{read of non-const}}
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break;
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}
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return;
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}
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// implicitly converted to a prvalue of type T, where the converted expression
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// is a literal constant expression
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bool a(int n) {
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constexpr char vowels[] = "aeiou";
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switch (n) {
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case vowels[0]:
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case vowels[1]:
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case vowels[2]:
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case vowels[3]:
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case vowels[4]:
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static_assert(!vowels[5], "unexpected number of vowels");
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return true;
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}
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return false;
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}
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// and the implicit conversion sequence contains only
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//
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// user-defined conversions,
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struct S { constexpr operator int() const { return 5; } };
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enum E : unsigned char { E5 = S(), E6, E10 = S() * 2, E1 = E5 / 5 };
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// lvalue-to-rvalue conversions,
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const E e10 = E10;
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template<E> struct T {};
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T<e10> s10;
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// integral promotions,
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enum class EE { EE32 = ' ', EE65 = 'A', EE1 = (short)1, EE5 = E5 };
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// integral conversions other than narrowing conversions,
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int b(unsigned n) {
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switch (n) {
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case E6:
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case EE::EE32: // expected-error {{not implicitly convertible}}
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case (int)EE::EE32:
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case 1000:
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case (long long)1e10: // expected-error {{case value evaluates to 10000000000, which cannot be narrowed to type 'unsigned int'}}
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case -3: // expected-error {{case value evaluates to -3, which cannot be narrowed to type 'unsigned int'}}
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return n;
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}
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return 0;
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}
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enum class EEE : unsigned short {
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a = E6,
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b = EE::EE32, // expected-error {{not implicitly convertible}}
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c = (int)EE::EE32,
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d = 1000,
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e = 123456, // expected-error {{enumerator value evaluates to 123456, which cannot be narrowed to type 'unsigned short'}}
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f = -3 // expected-error {{enumerator value evaluates to -3, which cannot be narrowed to type 'unsigned short'}}
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};
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template<unsigned char> using A = int;
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using Int = A<E6>;
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using Int = A<EE::EE32>; // expected-error {{not implicitly convertible}}
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using Int = A<(int)EE::EE32>;
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using Int = A<200>;
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using Int = A<1000>; // expected-error {{template argument evaluates to 1000, which cannot be narrowed to type 'unsigned char'}}
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using Int = A<-3>; // expected-error {{template argument evaluates to -3, which cannot be narrowed to type 'unsigned char'}}
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// Note, conversions from integral or unscoped enumeration types to bool are
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// integral conversions as well as boolean conversions.
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// FIXME: Per core issue 1407, this is not correct.
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template<typename T, T v> struct Val { static constexpr T value = v; };
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static_assert(Val<bool, E1>::value == 1, ""); // ok
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static_assert(Val<bool, '\0'>::value == 0, ""); // ok
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static_assert(Val<bool, U'\1'>::value == 1, ""); // ok
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static_assert(Val<bool, E5>::value == 1, ""); // expected-error {{5, which cannot be narrowed to type 'bool'}}
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// function pointer conversions [C++17]
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void noexcept_false() noexcept(false);
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void noexcept_true() noexcept(true);
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Val<decltype(&noexcept_false), &noexcept_true> remove_noexcept;
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Val<decltype(&noexcept_true), &noexcept_false> add_noexcept;
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#if __cplusplus > 201402L
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// expected-error@-2 {{value of type 'void (*)() noexcept(false)' is not implicitly convertible to 'void (*)() noexcept'}}
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#endif
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// (no other conversions are permitted)
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using Int = A<1.0>; // expected-error {{conversion from 'double' to 'unsigned char' is not allowed in a converted constant expression}}
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enum B : bool {
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True = &a, // expected-error {{conversion from 'bool (*)(int)' to 'bool' is not allowed in a converted constant expression}}
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False = 0.0, // expected-error {{conversion from 'double' to 'bool' is not allowed in a converted constant expression}}
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};
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void c() {
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// Note, promoted type of switch is 'int'.
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switch (bool b = a(5)) { // expected-warning {{boolean value}}
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case 0.0f: // expected-error {{conversion from 'float' to 'int' is not allowed in a converted constant expression}}
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break;
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}
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}
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template <bool B> int f() { return B; } // expected-note {{candidate template ignored: invalid explicitly-specified argument for template parameter 'B'}}
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template int f<&S::operator int>(); // expected-error {{does not refer to a function template}}
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template int f<(bool)&S::operator int>();
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int n = Val<bool, &S::operator int>::value; // expected-error-re {{conversion from 'int (S::*)(){{( __attribute__\(\(thiscall\)\))?}} const' to 'bool' is not allowed in a converted constant expression}}
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namespace NonConstLValue {
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struct S {
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constexpr operator int() const { return 10; }
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};
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S s; // not constexpr
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// Under the FDIS, this is not a converted constant expression.
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// Under the new proposed wording, it is.
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enum E : char { e = s };
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}
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