[C23][N3006] Documented behavior of underspecified object declaration… · llvm/llvm-project@b896d26 (original) (raw)
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// RUN: %clang_cc1 -std=c23 -verify %s
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/* WG14 N3006: Yes
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- Underspecified object declarations
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*/
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void struct_test(void) {
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struct S1 { int x, y; }; // expected-note {{field 'x' has type 'int' here}}
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auto normal_struct = (struct S1){ 1, 2 };
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auto normal_struct2 = (struct S1) { .x = 1, .y = 2 };
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auto underspecified_struct = (struct S2 { int x, y; }){ 1, 2 };
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auto underspecified_struct_redef = (struct S1 { char x, y; }){ 'A', 'B'}; // expected-error {{type 'struct S1' has incompatible definitions}} \
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expected-error {{cannot use 'auto' with array in C}} \
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expected-note {{field 'x' has type 'char' here}}
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auto underspecified_empty_struct = (struct S3 { }){ };
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auto zero_init_struct = (struct S4 { int x; }){ 0 };
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int field_struct = (struct S5 { int y; }){ 0 }.y;
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}
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void union_test(void) {
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union U1 { int a; double b; }; // expected-note {{field 'a' has type 'int' here}}
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auto normal_union_int = (union U1){ .a = 12 };
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auto normal_union_double = (union U1){ .b = 2.4 };
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auto underspecified_union = (union U2 { int a; double b; }){ .a = 34 };
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auto underspecified_union_redef = (union U1 { char a; double b; }){ .a = 'A' }; // expected-error {{type 'union U1' has incompatible definitions}} \
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expected-error {{cannot use 'auto' with array in C}} \
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expected-note {{field 'a' has type 'char' here}}
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auto underspecified_empty_union = (union U3 { }){ };
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}
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void enum_test(void) {
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enum E1 { FOO, BAR }; // expected-note {{enumerator 'BAR' with value 1 here}}
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auto normal_enum_foo = (enum E1){ FOO };
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auto normal_enum_bar = (enum E1){ BAR };
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auto underspecified_enum = (enum E2 { BAZ, QUX }){ BAZ };
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auto underspecified_enum_redef = (enum E1 { ONE, TWO }){ ONE }; // expected-error {{type 'enum E1' has incompatible definitions}} \
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expected-error {{cannot use 'auto' with array in C}} \
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expected-note {{enumerator 'ONE' with value 0 here}}
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auto underspecified_empty_enum = (enum E3 { }){ }; // expected-error {{use of empty enum}}
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auto underspecified_undeclared_enum = (enum E4){ FOO }; // expected-error {{variable has incomplete type 'enum E4'}} \
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expected-note {{forward declaration of 'enum E4'}}
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}
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void constexpr_test(void) {
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constexpr auto ce_struct = (struct S1){ 1, 2 }; // expected-error {{variable has incomplete type 'struct S1'}} \
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expected-note {{forward declaration of 'struct S1'}}
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constexpr auto ce_struct_zero_init = (struct S2 { int x; }){ 0 };
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constexpr int ce_struct_field = (struct S3 { int y; }){ 0 }.y;
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constexpr auto ce_union = (union U1){ .a = 12 }; // expected-error {{variable has incomplete type 'union U1'}} \
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expected-note {{forward declaration of 'union U1'}}
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constexpr auto ce_enum = (enum E1 { BAZ, QUX }){ BAZ };
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constexpr auto ce_empty_enum = (enum E2){ FOO }; // expected-error {{use of undeclared identifier 'FOO'}}
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}
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void self_reference_test(void) {
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constexpr int i = i; // expected-error {{constexpr variable 'i' must be initialized by a constant expression}} \
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expected-note {{read of object outside its lifetime is not allowed in a constant expression}}
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auto j = j; // expected-error {{variable 'j' declared with deduced type 'auto' cannot appear in its own initializer}}
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}
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void redefinition_test(void) {
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const struct S { int x; } s; // expected-warning {{default initialization of an object of type 'const struct S' leaves the object uninitialized}} \
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expected-note {{previous definition is here}}
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constexpr struct S s = {0}; // expected-error {{redefinition of 's'}}
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}
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void declaring_an_underspecified_defied_object_test(void) {
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struct S { int x, y; };
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constexpr int i = (struct T { int a, b; }){0, 1}.a;
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struct T t = { 1, 2 };
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}
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void constexpr_complience_test(void) {
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int x = (struct Foo { int x; }){ 0 }.x;
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constexpr int y = (struct Bar { int x; }){ 0 }.x;
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}
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void builtin_functions_test(void) {
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constexpr typeof(struct s *) x = 0;
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auto so = sizeof(struct S {});
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auto to = (typeof(struct S {})){};
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}
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void misc_test(void) {
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constexpr struct S { int a, b; } y = { 0 };
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constexpr int a = 0, b = 0;
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auto c = (struct T { int x, y; }){0, 0};
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auto s2 = ({struct T { int x; } s = {}; s.x; });
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auto s3 = ((struct {}){},0); // expected-warning {{left operand of comma operator has no effect}}
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constexpr int (*fp)(struct X { int x; } val) = 0;
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auto v = (void (*)(int y))0;
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}
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void misc_struct_test(void) {
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constexpr struct {
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int a;
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} a = {};
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constexpr struct {
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int b;
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} b = (struct S { int x; }){ 0 }; // expected-error-re {{initializing 'const struct (unnamed struct at {{.*}}n3006.c:104:13)' with an expression of incompatible type 'struct S'}}
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auto z = ({
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int a = 12;
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struct {} s;
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a;
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});
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}
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