[clang] a0f8890 - [clang][C23] Support N3029 Improved Normal Enumerations (#103917)
via cfe-commits
cfe-commits at lists.llvm.org
Fri Sep 13 02:11:38 PDT 2024
Author: Mariya Podchishchaeva
Date: 2024-09-13T11:11:34+02:00
New Revision: a0f88901a4e6a6618c3ec02108103d0415e28834
URL: https://github.com/llvm/llvm-project/commit/a0f88901a4e6a6618c3ec02108103d0415e28834
DIFF: https://github.com/llvm/llvm-project/commit/a0f88901a4e6a6618c3ec02108103d0415e28834.diff
LOG: [clang][C23] Support N3029 Improved Normal Enumerations (#103917)
Basically clang already implemented 90% of the feature as an extension.
This commit disables warnings for C23 and aligns types of enumerators
according to the recent wording.
Added:
clang/test/C/C23/n3029.c
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDecl.cpp
clang/test/Misc/warning-flags.c
clang/test/Sema/enum.c
clang/www/c_status.html
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c4fa017b982bbd..3929a9fb599259 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -179,6 +179,8 @@ C2y Feature Support
C23 Feature Support
^^^^^^^^^^^^^^^^^^^
+- Clang now supports `N3029 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3029.htm>`_ Improved Normal Enumerations.
+
Non-comprehensive list of changes in this release
-------------------------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index efdc058edca56d..3a465464bc5b47 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1039,7 +1039,6 @@ def err_opencl_invalid_param : Error<
"declaring function parameter of type %0 is not allowed%select{; did you forget * ?|}1">;
def err_opencl_invalid_return : Error<
"declaring function return value of type %0 is not allowed %select{; did you forget * ?|}1">;
-def warn_enum_value_overflow : Warning<"overflow in enumeration value">;
def warn_pragma_options_align_reset_failed : Warning<
"#pragma options align=reset failed: %0">,
InGroup<IgnoredPragmas>;
@@ -6194,9 +6193,13 @@ def err_misplaced_ivar : Error<
def warn_ivars_in_interface : Warning<
"declaration of instance variables in the interface is deprecated">,
InGroup<DiagGroup<"objc-interface-ivars">>, DefaultIgnore;
-def ext_enum_value_not_int : Extension<
- "ISO C restricts enumerator values to range of 'int' (%0 is too "
- "%select{small|large}1)">;
+def ext_c23_enum_value_not_int : Extension<
+ "%select{|incremented }0enumerator value which exceeds the range of 'int' is "
+ "a C23 extension (%1 is too %select{small|large}2)">, InGroup<C23>;
+def warn_c17_compat_enum_value_not_int : Warning<
+ "%select{|incremented }0enumerator value which exceeds the range of 'int' is "
+ "incompatible with C standards before C23 (%1 is too %select{small|large}2)">,
+ DefaultIgnore, InGroup<CPre23Compat>;
def ext_enum_too_large : ExtWarn<
"enumeration values exceed range of largest integer">, InGroup<EnumTooLarge>;
def ext_enumerator_increment_too_large : ExtWarn<
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 3c6a0dff798ff6..8557c25b93a8da 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -19479,11 +19479,13 @@ EnumConstantDecl *Sema::CheckEnumConstant(EnumDecl *Enum,
// representable as an int.
// Complain if the value is not representable in an int.
- if (!isRepresentableIntegerValue(Context, EnumVal, Context.IntTy))
- Diag(IdLoc, diag::ext_enum_value_not_int)
- << toString(EnumVal, 10) << Val->getSourceRange()
- << (EnumVal.isUnsigned() || EnumVal.isNonNegative());
- else if (!Context.hasSameType(Val->getType(), Context.IntTy)) {
+ if (!isRepresentableIntegerValue(Context, EnumVal, Context.IntTy)) {
+ Diag(IdLoc, getLangOpts().C23
+ ? diag::warn_c17_compat_enum_value_not_int
+ : diag::ext_c23_enum_value_not_int)
+ << 0 << toString(EnumVal, 10) << Val->getSourceRange()
+ << (EnumVal.isUnsigned() || EnumVal.isNonNegative());
+ } else if (!Context.hasSameType(Val->getType(), Context.IntTy)) {
// Force the type of the expression to 'int'.
Val = ImpCastExprToType(Val, Context.IntTy, CK_IntegralCast).get();
}
@@ -19558,17 +19560,22 @@ EnumConstantDecl *Sema::CheckEnumConstant(EnumDecl *Enum,
// If we're not in C++, diagnose the overflow of enumerator values,
// which in C99 means that the enumerator value is not representable in
- // an int (C99 6.7.2.2p2). However, we support GCC's extension that
- // permits enumerator values that are representable in some larger
- // integral type.
- if (!getLangOpts().CPlusPlus && !T.isNull())
- Diag(IdLoc, diag::warn_enum_value_overflow);
- } else if (!getLangOpts().CPlusPlus &&
- !EltTy->isDependentType() &&
+ // an int (C99 6.7.2.2p2). However C23 permits enumerator values that
+ // are representable in some larger integral type and we allow it in
+ // older language modes as an extension.
+ // Exclude fixed enumerators since they are diagnosed with an error for
+ // this case.
+ if (!getLangOpts().CPlusPlus && !T.isNull() && !Enum->isFixed())
+ Diag(IdLoc, getLangOpts().C23
+ ? diag::warn_c17_compat_enum_value_not_int
+ : diag::ext_c23_enum_value_not_int)
+ << 1 << toString(EnumVal, 10) << 1;
+ } else if (!getLangOpts().CPlusPlus && !EltTy->isDependentType() &&
!isRepresentableIntegerValue(Context, EnumVal, EltTy)) {
// Enforce C99 6.7.2.2p2 even when we compute the next value.
- Diag(IdLoc, diag::ext_enum_value_not_int)
- << toString(EnumVal, 10) << 1;
+ Diag(IdLoc, getLangOpts().C23 ? diag::warn_c17_compat_enum_value_not_int
+ : diag::ext_c23_enum_value_not_int)
+ << 1 << toString(EnumVal, 10) << 1;
}
}
}
@@ -19887,9 +19894,6 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
return;
}
- // TODO: If the result value doesn't fit in an int, it must be a long or long
- // long value. ISO C does not support this, but GCC does as an extension,
- // emit a warning.
unsigned IntWidth = Context.getTargetInfo().getIntWidth();
unsigned CharWidth = Context.getTargetInfo().getCharWidth();
unsigned ShortWidth = Context.getTargetInfo().getShortWidth();
@@ -19898,13 +19902,14 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
// reverse the list.
unsigned NumNegativeBits = 0;
unsigned NumPositiveBits = 0;
+ bool MembersRepresentableByInt = true;
for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
EnumConstantDecl *ECD =
cast_or_null<EnumConstantDecl>(Elements[i]);
if (!ECD) continue; // Already issued a diagnostic.
- const llvm::APSInt &InitVal = ECD->getInitVal();
+ llvm::APSInt InitVal = ECD->getInitVal();
// Keep track of the size of positive and negative values.
if (InitVal.isUnsigned() || InitVal.isNonNegative()) {
@@ -19916,6 +19921,8 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
NumNegativeBits =
std::max(NumNegativeBits, (unsigned)InitVal.getSignificantBits());
}
+ MembersRepresentableByInt &=
+ isRepresentableIntegerValue(Context, InitVal, Context.IntTy);
}
// If we have an empty set of enumerators we still need one bit.
@@ -19937,7 +19944,7 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
// int, long long int, or unsigned long long int.
// C99 6.4.4.3p2:
// An identifier declared as an enumeration constant has type int.
- // The C99 rule is modified by a gcc extension
+ // The C99 rule is modified by C23.
QualType BestPromotionType;
bool Packed = Enum->hasAttr<PackedAttr>();
@@ -20031,7 +20038,7 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
auto *ECD = cast_or_null<EnumConstantDecl>(D);
if (!ECD) continue; // Already issued a diagnostic.
- // Standard C says the enumerators have int type, but we allow, as an
+ // C99 says the enumerators have int type, but we allow, as an
// extension, the enumerators to be larger than int size. If each
// enumerator value fits in an int, type it as an int, otherwise type it the
// same as the enumerator decl itself. This means that in "enum { X = 1U }"
@@ -20045,9 +20052,14 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
QualType NewTy;
unsigned NewWidth;
bool NewSign;
- if (!getLangOpts().CPlusPlus &&
- !Enum->isFixed() &&
- isRepresentableIntegerValue(Context, InitVal, Context.IntTy)) {
+ if (!getLangOpts().CPlusPlus && !Enum->isFixed() &&
+ MembersRepresentableByInt) {
+ // C23 6.7.3.3.3p15:
+ // The enumeration member type for an enumerated type without fixed
+ // underlying type upon completion is:
+ // - int if all the values of the enumeration are representable as an
+ // int; or,
+ // - the enumerated type
NewTy = Context.IntTy;
NewWidth = IntWidth;
NewSign = true;
diff --git a/clang/test/C/C23/n3029.c b/clang/test/C/C23/n3029.c
new file mode 100644
index 00000000000000..26d6dfdcc60462
--- /dev/null
+++ b/clang/test/C/C23/n3029.c
@@ -0,0 +1,65 @@
+// RUN: %clang_cc1 -verify=expected,all -triple x86_64-unknown-linux-gnu -fsyntax-only -std=c23 %s -Wpre-c23-compat
+// RUN: %clang_cc1 -verify=pedantic,all -triple x86_64-unknown-linux-gnu -fsyntax-only -std=c17 %s -pedantic
+
+#include <limits.h>
+
+#define GET_TYPE_INT(x) _Generic(x, \
+ char: 1,\
+ unsigned char: 2,\
+ signed char: 3,\
+ short: 4,\
+ unsigned short: 5,\
+ int: 6,\
+ unsigned int: 7,\
+ long: 8,\
+ unsigned long: 9,\
+ long long: 10,\
+ unsigned long long: 11,\
+ default: 0xFF\
+ )\
+
+enum x {
+a = INT_MAX,
+b = ULLONG_MAX, // expected-warning {{enumerator value which exceeds the range of 'int' is incompatible with C standards before C23}}
+ // pedantic-warning at -1 {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+a_type = GET_TYPE_INT(a),
+b_type = GET_TYPE_INT(b)
+};
+
+_Static_assert(GET_TYPE_INT(a) == GET_TYPE_INT(b), "ok");
+
+extern enum x e_a;
+extern __typeof(b) e_a;
+extern __typeof(a) e_a;
+
+enum a {
+ a0 = 0xFFFFFFFFFFFFFFFFULL // expected-warning {{enumerator value which exceeds the range of 'int' is incompatible with C standards before C23}}
+ // pedantic-warning at -1 {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+};
+
+_Bool e (void) {
+ return a0;
+}
+
+int f (void) {
+ return a0; // all-warning {{implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1}}
+}
+
+unsigned long g (void) {
+ return a0;
+}
+
+unsigned long long h (void) {
+ return a0;
+}
+
+enum big_enum {
+ big_enum_a = LONG_MAX, // expected-warning {{enumerator value which exceeds the range of 'int' is incompatible with C standards before C23}}
+ // pedantic-warning at -1 {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+ big_enum_b = a + 1, // expected-warning {{enumerator value which exceeds the range of 'int' is incompatible with C standards before C23}}
+ // pedantic-warning at -1 {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+ big_enum_c = ULLONG_MAX // expected-warning {{enumerator value which exceeds the range of 'int' is incompatible with C standards before C23}}
+ // pedantic-warning at -1 {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+};
+
+_Static_assert(GET_TYPE_INT(big_enum_a) == GET_TYPE_INT(big_enum_b), "ok");
diff --git a/clang/test/Misc/warning-flags.c b/clang/test/Misc/warning-flags.c
index e4e16f074cef33..80c01099140f79 100644
--- a/clang/test/Misc/warning-flags.c
+++ b/clang/test/Misc/warning-flags.c
@@ -18,7 +18,7 @@ This test serves two purposes:
The list of warnings below should NEVER grow. It should gradually shrink to 0.
-CHECK: Warnings without flags (63):
+CHECK: Warnings without flags (62):
CHECK-NEXT: ext_expected_semi_decl_list
CHECK-NEXT: ext_missing_whitespace_after_macro_name
@@ -46,7 +46,6 @@ CHECK-NEXT: warn_drv_amdgpu_cov6
CHECK-NEXT: warn_drv_assuming_mfloat_abi_is
CHECK-NEXT: warn_drv_clang_unsupported
CHECK-NEXT: warn_drv_pch_not_first_include
-CHECK-NEXT: warn_enum_value_overflow
CHECK-NEXT: warn_expected_qualified_after_typename
CHECK-NEXT: warn_fe_backend_unsupported
CHECK-NEXT: warn_fe_cc_log_diagnostics_failure
@@ -86,4 +85,4 @@ CHECK-NEXT: warn_weak_import
The list of warnings in -Wpedantic should NEVER grow.
-CHECK: Number in -Wpedantic (not covered by other -W flags): 25
+CHECK: Number in -Wpedantic (not covered by other -W flags): 24
diff --git a/clang/test/Sema/enum.c b/clang/test/Sema/enum.c
index b0707914c0d852..4f6d04ba7f9182 100644
--- a/clang/test/Sema/enum.c
+++ b/clang/test/Sema/enum.c
@@ -1,23 +1,23 @@
-// RUN: %clang_cc1 -triple %itanium_abi_triple %s -fsyntax-only -verify -pedantic
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -fsyntax-only -std=c23 -verify -pedantic
+// RUN: %clang_cc1 -triple %itanium_abi_triple %s -fsyntax-only -verify=expected,pre-c23 -pedantic
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -fsyntax-only -std=c23 -verify=expected -pedantic
enum e {A,
- B = 42LL << 32, // expected-warning {{ISO C restricts enumerator values to range of 'int'}}
+ B = 42LL << 32, // pre-c23-warning {{enumerator value which exceeds the range of 'int' is a C23 extension}}
C = -4, D = 12456 };
enum f { a = -2147483648, b = 2147483647 }; // ok.
enum g { // too negative
- c = -2147483649, // expected-warning {{ISO C restricts enumerator values to range of 'int'}}
+ c = -2147483649, // pre-c23-warning {{enumerator value which exceeds the range of 'int' is a C23 extension}}
d = 2147483647 };
enum h { e = -2147483648, // too pos
- f = 2147483648, // expected-warning {{ISO C restricts enumerator values to range of 'int'}}
- i = 0xFFFF0000 // expected-warning {{too large}}
+ f = 2147483648, // pre-c23-warning {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+ i = 0xFFFF0000 // pre-c23-warning {{too large}}
};
// minll maxull
enum x // expected-warning {{enumeration values exceed range of largest integer}}
-{ y = -9223372036854775807LL-1, // expected-warning {{ISO C restricts enumerator values to range of 'int'}}
-z = 9223372036854775808ULL }; // expected-warning {{ISO C restricts enumerator values to range of 'int'}}
+{ y = -9223372036854775807LL-1, // pre-c23-warning {{enumerator value which exceeds the range of 'int' is a C23 extension}}
+z = 9223372036854775808ULL }; // pre-c23-warning {{enumerator value which exceeds the range of 'int' is a C23 extension}}
int test(void) {
return sizeof(enum e) ;
@@ -169,13 +169,16 @@ enum class GH42372_2 {
One
};
+enum IncOverflow {
+ V2 = __INT_MAX__,
+ V3 // pre-c23-warning {{incremented enumerator value which exceeds the range of 'int' is a C23 extension}}
+};
+
#if __STDC_VERSION__ >= 202311L
// FIXME: GCC picks __uint128_t as the underlying type for the enumeration
// value and Clang picks unsigned long long.
-// FIXME: Clang does not yet implement WG14 N3029, so the warning about
-// restricting enumerator values to 'int' is not correct.
enum GH59352 { // expected-warning {{enumeration values exceed range of largest integer}}
- BigVal = 66666666666666666666wb // expected-warning {{ISO C restricts enumerator values to range of 'int' (66666666666666666666 is too large)}}
+ BigVal = 66666666666666666666wb
};
_Static_assert(BigVal == 66666666666666666666wb); /* expected-error {{static assertion failed due to requirement 'BigVal == 66666666666666666666wb'}}
expected-note {{expression evaluates to '11326434445538011818 == 66666666666666666666'}}
@@ -191,4 +194,38 @@ _Static_assert(
__uint128_t : 1
)
);
+
+#include <limits.h>
+
+void fooinc23() {
+ enum E1 {
+ V1 = INT_MAX
+ } e1;
+
+ enum E2 {
+ V2 = INT_MAX,
+ V3
+ } e2;
+
+ enum E3 {
+ V4 = INT_MAX,
+ V5 = LONG_MIN
+ } e3;
+
+ enum E4 {
+ V6 = 1u,
+ V7 = 2wb
+ } e4;
+
+ _Static_assert(_Generic(V1, int : 1));
+ _Static_assert(_Generic(V2, int : 0, unsigned int : 1));
+ _Static_assert(_Generic(V3, int : 0, unsigned int : 1));
+ _Static_assert(_Generic(V4, int : 0, signed long : 1));
+ _Static_assert(_Generic(V5, int : 0, signed long : 1));
+ _Static_assert(_Generic(V6, int : 1));
+ _Static_assert(_Generic(V7, int : 1));
+ _Static_assert(_Generic((enum E4){}, unsigned int : 1));
+
+}
+
#endif // __STDC_VERSION__ >= 202311L
diff --git a/clang/www/c_status.html b/clang/www/c_status.html
index 255690cd6d34e2..6e37dd65ccbdee 100644
--- a/clang/www/c_status.html
+++ b/clang/www/c_status.html
@@ -687,7 +687,7 @@ <h2 id="c2x">C23 implementation status</h2>
<tr>
<td>Improved normal enumerations</td>
<td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3029.htm">N3029</a></td>
- <td class="unknown" align="center">Unknown</td>
+ <td class="unreleased" align="center">Clang 20</td>
</tr>
<tr>
<td>Relax requirements for va_start</td>
More information about the cfe-commits
mailing list