================
@@ -0,0 +1,456 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c23 -pedantic -Wall -Wno-comment
-verify=both,c23 %s
+// RUN: %clang_cc1 -fsyntax-only -std=c17 -pedantic -Wall -Wno-comment
-Wno-c23-extensions -verify=both,c17 %s
+
+/* WG14 N3037:
+ * Improved tag compatibility
+ *
+ * Identical tag types have always been compatible across TU boundaries. This
+ * paper made identical tag types compatible within the same TU.
+ */
+
+struct foo { int a; } p;
+
+void baz(struct foo f); // c17-note {{passing argument to parameter 'f' here}}
+
+void bar(void) {
+ struct foo { int a; } q = {};
+ baz(q); // c17-error {{passing 'struct foo' to parameter of incompatible
type 'struct foo'}}
+}
+
+#define PRODUCT(A ,B) struct prod { A a; B b; } //
expected-note 2 {{expanded from macro 'PRODUCT'}}
+#define SUM(A, B) struct sum { _Bool flag; union { A a; B b; }; } //
expected-note 2 {{expanded from macro 'SUM'}}
+
+void func1(PRODUCT(int, SUM(float, double)) x); // both-warning {{declaration
of 'struct prod' will not be visible outside of this function}} \
+ both-warning {{declaration
of 'struct sum' will not be visible outside of this function}} \
+ c17-note {{passing argument
to parameter 'x' here}}
+void func2(PRODUCT(int, SUM(float, double)) y) { // both-warning {{declaration
of 'struct prod' will not be visible outside of this function}} \
+ both-warning {{declaration
of 'struct sum' will not be visible outside of this function}}
+ func1(y); // c17-error {{passing 'struct prod' to parameter of incompatible
type 'struct prod'}}
+}
+
+struct foop { struct { int x; }; }; // c17-note {{previous definition is here}}
+struct foop { struct { int x; }; }; // c17-error {{redefinition of 'foop'}}
+union barp { int x; float y; }; // c17-note {{previous definition is here}}
+union barp { int x; float y; }; // c17-error {{redefinition of 'barp'}}
+typedef struct q { int x; } q_t; // c17-note 2 {{previous definition is
here}}
+typedef struct q { int x; } q_t; // c17-error {{redefinition of 'q'}} \
+ c17-error-re {{typedef redefinition
with different types ('struct (unnamed struct at {{.*}})' vs 'struct q')}}
+void func3(void) {
+ struct S { int x; }; // c17-note {{previous definition is here}}
+ struct T { struct S s; }; // c17-note {{previous definition is here}}
+ struct S { int x; }; // c17-error {{redefinition of 'S'}}
+ struct T { struct S s; }; // c17-error {{redefinition of 'T'}}
+}
+
+struct food { int (*p)[3]; }; // c23-note {{field 'p' has type 'int (*)[3]'
here}} \
+ c17-note {{previous definition is here}}
+struct food { int (*p)[]; }; // c23-error {{type 'struct food' has
incompatible definitions}} \
+ c23-note {{field 'p' has type 'int (*)[]'
here}} \
+ c17-error {{redefinition of 'food'}}
+union bard { int x; float y; }; // c23-note {{field has name 'x' here}} \
+ c17-note {{previous definition is here}}
+union bard { int z; float y; }; // c23-error {{type 'union bard' has
incompatible definitions}} \
+ c23-note {{field has name 'z' here}} \
+ c17-error {{redefinition of 'bard'}}
+union purr { int x; float y; }; // c23-note {{field has name 'x' here}} \
+ c17-note {{previous definition is here}}
+union purr { float y; int x; }; // c23-error {{type 'union purr' has
incompatible definitions}} \
+ c23-note {{field has name 'y' here}} \
+ c17-error {{redefinition of 'purr'}}
+
+// Different attributes on the tag type are an error.
+struct [[gnu::packed]] attr_test { // c17-note {{previous definition is here}}
\
+ c23-note {{attribute 'packed' here}}
+ int x;
+};
+
+struct attr_test { // c17-error {{redefinition of 'attr_test'}} \
+ c23-error {{type 'struct attr_test' has incompatible
definitions}} \
+ c23-note {{no corresponding attribute here}}
+ int x;
+};
+
+struct attr_test_2 { // c17-note {{previous definition is here}} \
+ c23-note {{no corresponding attribute here}}
+ int x;
+};
+
+struct [[gnu::packed]] attr_test_2 { // c17-error {{redefinition of
'attr_test_2'}} \
+ c23-error {{type 'struct attr_test_2'
has incompatible definitions}} \
+ c23-note {{attribute 'packed' here}}
+ int x;
+};
+
+struct [[deprecated]] attr_test_3 { // c17-note {{previous definition is
here}} \
+ c23-note {{attribute 'deprecated' here}}
+ int x;
+};
+
+struct [[gnu::packed]] attr_test_3 { // c17-error {{redefinition of
'attr_test_3'}} \
+ c23-error {{type 'struct attr_test_3'
has incompatible definitions}} \
+ c23-note {{attribute 'packed' here}}
+ int x;
+};
+
+// Same attribute works fine!
+struct [[deprecated]] attr_test_4 { // c17-note {{previous definition is here}}
+ int x;
+};
+
+struct [[deprecated]] attr_test_4 { // c17-error {{redefinition of
'attr_test_4'}}
+ int x;
+};
+
+// Same attribute with the same arguments is also fine.
+struct [[deprecated("testing")]] attr_test_5 { // c17-note {{previous
definition is here}}
+ int x;
+};
+
+struct [[deprecated("testing")]] attr_test_5 { // c17-error {{redefinition of
'attr_test_5'}}
+ int x;
+};
+
+// Same attribute with different arguments is not allowed. FIXME: it would be
+// nicer to explain that the arguments are different, but attribute argument
+// handling is already challenging.
+struct [[deprecated("testing")]] attr_test_6 { // c17-note {{previous
definition is here}} \
+ c23-note {{attribute
'deprecated' here}}
+ int x;
+};
+
+struct [[deprecated("oh no!")]] attr_test_6 { // c17-error {{redefinition of
'attr_test_6'}} \
+ c23-error {{type 'struct
attr_test_6' has incompatible definitions}} \
+ c23-note {{attribute
'deprecated' here}}
+ int x;
+};
+
+// Different attributes on the fields make them incompatible.
+struct field_attr_test_1 { // c17-note {{previous definition is here}}
+ int x;
+ [[gnu::packed]] int y; // c23-note {{attribute 'packed' here}}
+};
+
+struct field_attr_test_1 { // c17-error {{redefinition of
'field_attr_test_1'}} \
+ c23-error {{type 'struct field_attr_test_1' has
incompatible definitions}}
+ int x;
+ int y; // c23-note {{no corresponding attribute here}}
+};
+
+struct field_attr_test_2 { // c17-note {{previous definition is here}}
+ [[gnu::packed]] int x; // c23-note {{attribute 'packed' here}}
+ int y;
+};
+
+struct field_attr_test_2 { // c17-error {{redefinition of
'field_attr_test_2'}} \
+ c23-error {{type 'struct field_attr_test_2' has
incompatible definitions}}
+ int x; // c23-note {{no corresponding attribute here}}
+ int y;
+};
+
+struct field_attr_test_3 { // c17-note {{previous definition is here}}
+ [[gnu::packed]] int x;
+ int y;
+};
+
+struct field_attr_test_3 { // c17-error {{redefinition of 'field_attr_test_3'}}
+ int x [[gnu::packed]];
+ int y;
+};
+
+struct field_attr_test_4 { // c17-note {{previous definition is here}}
+ [[gnu::packed]] int x; // c23-note {{attribute 'packed' here}}
+ int y;
+};
+
+struct field_attr_test_4 { // c17-error {{redefinition of
'field_attr_test_4'}} \
+ c23-error {{type 'struct field_attr_test_4' has
incompatible definitions}}
+ [[deprecated]] int x; // c23-note {{attribute 'deprecated' here}}
+ int y;
+};
+
+struct field_attr_test_5 { // c17-note {{previous definition is here}}
+ [[deprecated("testing")]] int x;
+ int y;
+};
+
+struct field_attr_test_5 { // c17-error {{redefinition of 'field_attr_test_5'}}
+ [[deprecated("testing")]] int x;
+ int y;
+};
+
+// Show that attribute order does not matter.
+struct [[deprecated("testing"), gnu::packed]] field_attr_test_6 { // c17-note
{{previous definition is here}}
+ int x;
+ int y;
+};
+
+struct [[gnu::packed, deprecated("testing")]] field_attr_test_6 { // c17-error
{{redefinition of 'field_attr_test_6'}}
+ int x;
+ int y;
+};
+
+// Show that attribute syntax does matter.
+// FIXME: more clearly identify the syntax as the problem.
+struct [[gnu::packed]] field_attr_test_7 { // c17-note {{previous definition
is here}} \
+ c23-note {{attribute 'packed'
here}}
+ int x;
+ int y;
+};
+
+struct __attribute__((packed)) field_attr_test_7 { // c17-error {{redefinition
of 'field_attr_test_7'}} \
+ c23-error {{type 'struct
field_attr_test_7' has incompatible definitions}} \
+ c23-note {{attribute
'packed' here}}
+ int x;
+ int y;
+};
+
+// Show that attribute *spelling* matters. These two attributes share the same
+// implementation in the AST, but the spelling still matters.
+struct [[nodiscard]] field_attr_test_8 { // c17-note {{previous definition is
here}} \
+ c23-note {{attribute 'nodiscard'
here}}
+ int x;
+ int y;
+};
+
+struct [[gnu::warn_unused_result]] field_attr_test_8 { // c17-error
{{redefinition of 'field_attr_test_8'}} \
+ c23-error {{type
'struct field_attr_test_8' has incompatible definitions}} \
+ c23-note {{attribute
'warn_unused_result' here}}
+ int x;
+ int y;
+};
+
+
+// Show that equivalent field types are not an issue.
+typedef int typedef_of_type_int;
+struct equivalent_field_types { // c17-note {{previous definition is here}}
+ int x;
+};
+
+struct equivalent_field_types { // c17-error {{redefinition of
'equivalent_field_types'}}
+ typedef_of_type_int x;
+};
+
+struct quals_matter { // c17-note {{previous definition is here}}
+ int x; // c23-note {{field 'x' has type 'int' here}}
+};
+
+struct quals_matter { // c17-error {{redefinition of 'quals_matter'}} \
+ c23-error {{type 'struct quals_matter' has
incompatible definitions}}
+ const int x; // c23-note {{field 'x' has type 'const int' here}}
+};
+
+struct qual_order_does_not_matter { // c17-note {{previous definition is here}}
+ const volatile int x;
+};
+
+struct qual_order_does_not_matter { // c17-error {{redefinition of
'qual_order_does_not_matter'}}
+ volatile const int x;
+};
+
+struct nested { // both-note {{previous definition is here}}
+ int x;
+ struct nested { // both-error {{nested redefinition of 'nested'}}
+ int x;
+ };
+};
+
+// Show that bit-field order does matter, including anonymous bit-fields.
+struct bit_field_1 { // c17-note 2 {{previous definition is here}}
+ int a : 1;
+ int : 0; // c23-note {{field has name '' here}}
+ int b : 1;
+};
+
+struct bit_field_1 { // c17-error {{redefinition of 'bit_field_1'}}
+ int a : 1;
+ int : 0;
+ int b : 1;
+};
+
+struct bit_field_1 { // c17-error {{redefinition of 'bit_field_1'}} \
+ c23-error {{type 'struct bit_field_1' has incompatible
definitions}}
+ int a : 1;
+ int b : 1; // c23-note {{field has name 'b' here}}
+};
+
+struct bit_field_2 { // c17-note {{previous definition is here}}
+ int a : 1;
+ int b : 1; // c23-note {{bit-field 'b' has bit-width 1 here}}
+};
+
+struct bit_field_2 { // c17-error {{redefinition of 'bit_field_2'}} \
+ c23-error {{type 'struct bit_field_2' has incompatible
definitions}}
+ int a : 1;
+ int b : 2; // c23-note {{bit-field 'b' has bit-width 2 here}}
+};
+
+// Test a bit-field with an attribute.
+struct bit_field_3 { // c17-note {{previous definition is here}}
+ int a : 1;
+ int b : 1; // c23-note {{no corresponding attribute here}}
+};
+
+struct bit_field_3 { // c17-error {{redefinition of 'bit_field_3'}} \
+ c23-error {{type 'struct bit_field_3' has incompatible
definitions}}
+ int a : 1;
+ [[deprecated]] int b : 1; // c23-note {{attribute 'deprecated' here}}
+};
+
+struct bit_field_4 { // c17-note {{previous definition is here}}
+ int a : 1;
+ int b : 1; // c23-note {{bit-field 'b' has bit-width 1 here}}
+};
+
+struct bit_field_4 { // c17-error {{redefinition of 'bit_field_4'}} \
+ c23-error {{type 'struct bit_field_4' has incompatible
definitions}}
+ int a : 1;
+ int b; // c23-note {{field 'b' is not a bit-field}}
+};
+
+struct bit_field_5 { // c17-note {{previous definition is here}}
+ int a : 1;
+ int b; // c23-note {{field 'b' is not a bit-field}}
+};
+
+struct bit_field_5 { // c17-error {{redefinition of 'bit_field_5'}} \
+ c23-error {{type 'struct bit_field_5' has incompatible
definitions}}
+ int a : 1;
+ int b : 1; // c23-note {{bit-field 'b' has bit-width 1 here}}
+};
+
+enum E { A }; // c17-note 2 {{previous definition is here}}
+enum E { A }; // c17-error {{redefinition of 'E'}} \
+ c17-error {{redefinition of enumerator 'A'}}
+
+enum Q { D = 1 }; // c17-note 2 {{previous definition is here}}
+enum Q { D = D }; // c17-error {{redefinition of 'Q'}} \
+ c17-error {{redefinition of enumerator 'D'}}
+
+// The order of the enumeration constants does not matter, only the values do.
+enum X { B = 1, C = 1 + 1 }; // c17-note 3 {{previous definition is here}}
+enum X { C = 2, B = 1 }; // c17-error {{redefinition of 'X'}} \
+ c17-error {{redefinition of enumerator 'C'}} \
+ c17-error {{redefinition of enumerator 'B'}}
+
+// Different enumeration constants.
+enum Y { YA = 1, YB = 2 }; // c23-note {{enumerator 'YB' with value 2 here}} \
+ c17-note 3 {{previous definition is here}}
+enum Y { YA = 1, YB = 3 }; // c23-error {{type 'enum Y' has incompatible
definitions}} \
+ c23-note {{enumerator 'YB' with value 3 here}} \
+ c17-error {{redefinition of 'Y'}} \
+ c17-error
{{redefinition of enumerator 'YA'}} \
+ c17-error {{redefinition of enumerator 'YB'}}
+
+// Different enumeration names, same named constants.
+enum Z1 { ZC = 1 }; // both-note {{previous definition is here}}
+enum Z2 { ZC = 1 }; // both-error {{redefinition of enumerator 'ZC'}}
+
+// Test attributes on the enumeration and enumerators.
+enum [[deprecated]] enum_attr_test_1 { // c17-note {{previous definition is
here}}
+ EAT1 [[deprecated]] // c17-note {{previous definition is here}}
+};
+
+enum [[deprecated]] enum_attr_test_1 { // c17-error {{redefinition of
'enum_attr_test_1'}}
+ EAT1 [[deprecated]] // c17-error {{redefinition of enumerator 'EAT1'}}
+};
+
+enum [[deprecated]] enum_attr_test_2 { // c17-note {{previous definition is
here}} \
+ c23-note {{attribute 'deprecated'
here}}
+ EAT2 // c17-note {{previous definition is here}}
+};
+
+enum enum_attr_test_2 { // c17-error {{redefinition of 'enum_attr_test_2'}} \
+ c23-error {{type 'enum enum_attr_test_2' has
incompatible definition}} \
+ c23-note {{no corresponding attribute here}}
+ EAT2 // c17-error {{redefinition of enumerator 'EAT2'}}
+};
+
+enum enum_attr_test_3 { // c17-note {{previous definition is here}} \
+ c23-note {{no corresponding attribute here}}
+ EAT3 // c17-note {{previous definition is here}}
+};
+
+enum [[deprecated]] enum_attr_test_3 { // c17-error {{redefinition of
'enum_attr_test_3'}} \
+ c23-error {{type 'enum
enum_attr_test_3' has incompatible definition}} \
+ c23-note {{attribute 'deprecated'
here}}
+ EAT3 // c17-error {{redefinition of enumerator 'EAT3'}}
+};
+
+enum [[clang::flag_enum]] enum_attr_test_4 { // c17-note {{previous definition
is here}} \
+ c23-note {{attribute
'flag_enum' here}}
+ EAT4 // c17-note {{previous definition is here}}
+};
+
+enum [[deprecated]] enum_attr_test_4 { // c17-error {{redefinition of
'enum_attr_test_4'}} \
+ c23-error {{type 'enum
enum_attr_test_4' has incompatible definition}} \
+ c23-note {{attribute 'deprecated'
here}}
+ EAT4 // c17-error {{redefinition of enumerator 'EAT4'}}
+};
+
+enum enum_attr_test_5 { // c17-note {{previous definition is here}}
+ EAT5 [[deprecated]] // c17-note {{previous definition is here}} \
+ c23-note {{attribute 'deprecated' here}}
+};
+
+enum enum_attr_test_5 { // c17-error {{redefinition of 'enum_attr_test_5'}} \
+ c23-error {{type 'enum enum_attr_test_5' has
incompatible definition}}
+ EAT5 // c17-error {{redefinition of enumerator 'EAT5'}} \
+ c23-note {{no corresponding attribute here}}
+};
+
+enum enum_attr_test_6 { // c17-note {{previous definition is here}}
+ EAT6 // c17-note {{previous definition is here}} \
+ c23-note {{no corresponding attribute here}}
+};
+
+enum enum_attr_test_6 { // c17-error {{redefinition of 'enum_attr_test_6'}} \
+ c23-error {{type 'enum enum_attr_test_6' has
incompatible definition}}
+ EAT6 [[deprecated]] // c17-error {{redefinition of enumerator 'EAT6'}} \
+ c23-note {{attribute 'deprecated' here}}
+};
+
+// You cannot declare one with a fixed underlying type and the other without a
+// fixed underlying type, or a different underlying type. However, it's worth
+// showing that the underlying type doesn't change the redefinition behavior.
+enum fixed_test_1 : int { FT1 }; // c17-note 2 {{previous definition is here}}
+enum fixed_test_1 : int { FT1 }; // c17-error {{redefinition of
'fixed_test_1'}} \
+ c17-error {{redefinition of enumerator
'FT1'}}
+
+enum fixed_test_2 : int { FT2 }; // c17-note 2 {{previous
definition is here}}
+enum fixed_test_2 : typedef_of_type_int { FT2 }; // c17-error {{redefinition
of 'fixed_test_2'}} \
+ c17-error {{redefinition
of enumerator 'FT2'}}
+
+// Test more bizarre situations in terms of where the type is declared. This
+// has always been allowed.
+struct declared_funny_1 { int x; }
+declared_funny_func(struct declared_funny_1 { int x; } arg) { // both-warning
{{declaration of 'struct declared_funny_1' will not be visible outside of this
function}}
+ return declared_funny_func((__typeof__(arg)){ 0 });
+}
+
+// However, this is new.
+struct Outer {
+ struct Inner { // c17-note {{previous definition is here}}
+ int x;
+ } i;
+
+ enum InnerEnum { // c17-note {{previous definition is here}}
+ IE1 // c17-note {{previous definition is here}}
+ } j;
+};
+
+struct Inner { // c17-error {{redefinition of 'Inner'}}
+ int x;
+};
+
+enum InnerEnum { // c17-error {{redefinition of 'InnerEnum'}}
+ IE1 // c17-error {{redefinition of enumerator 'IE1'}}
+};
+
+void hidden(void) {
+ struct hidden_struct { int x; };
+}
+
+struct hidden_struct { // This is fine because the previous declaration is not
visible.
+ int y;
+ int z;
+};
----------------
AaronBallman wrote:
I'll add test coverage
https://github.com/llvm/llvm-project/pull/132939
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