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6 changes: 6 additions & 0 deletions clang/docs/ReleaseNotes.rst
Original file line number Diff line number Diff line change
Expand Up @@ -274,6 +274,12 @@ C Language Changes
C2y Feature Support
^^^^^^^^^^^^^^^^^^^

- Clang updated conformance for `N3370 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3370.htm>`_
case range expressions. This feature was previously supported by Clang as a
GNU extension, so ``-Wgnu-case-range`` no longer has effect in C modes, as
this is now a C2y extension in C. ``-Wgnu-case-range`` still applies in C++
modes.

C23 Feature Support
^^^^^^^^^^^^^^^^^^^

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9 changes: 7 additions & 2 deletions clang/include/clang/Basic/DiagnosticParseKinds.td
Original file line number Diff line number Diff line change
Expand Up @@ -203,8 +203,13 @@ def err_expected_equal_designator : Error<"expected '=' or another designator">;
def ext_gnu_old_style_field_designator : ExtWarn<
"use of GNU old-style field designator extension">,
InGroup<GNUDesignator>;
def ext_gnu_case_range : Extension<"use of GNU case range extension">,
InGroup<GNUCaseRange>;
def ext_gnu_case_range : Extension<
"case ranges are a GNU extension">, InGroup<GNUCaseRange>;
def warn_c23_compat_case_range : Warning<
"case ranges are incompatible with C standards before C2y">,
DefaultIgnore, InGroup<CPre2yCompat>;
def ext_c2y_case_range : Extension<
"case ranges are a C2y extension">, InGroup<C2y>;

// Generic errors.
def err_expected_expression : Error<"expected expression">;
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10 changes: 9 additions & 1 deletion clang/lib/Parse/ParseStmt.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -890,7 +890,15 @@ StmtResult Parser::ParseCaseStatement(ParsedStmtContext StmtCtx,
SourceLocation DotDotDotLoc;
ExprResult RHS;
if (TryConsumeToken(tok::ellipsis, DotDotDotLoc)) {
Diag(DotDotDotLoc, diag::ext_gnu_case_range);
// In C++, this is a GNU extension. In C, it's a C2y extension.
unsigned DiagId;
if (getLangOpts().CPlusPlus)
DiagId = diag::ext_gnu_case_range;
else if (getLangOpts().C2y)
DiagId = diag::warn_c23_compat_case_range;
else
DiagId = diag::ext_c2y_case_range;
Diag(DotDotDotLoc, DiagId);
RHS = ParseCaseExpression(CaseLoc);
if (RHS.isInvalid()) {
if (!SkipUntil(tok::colon, tok::r_brace, StopAtSemi | StopBeforeMatch))
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105 changes: 105 additions & 0 deletions clang/test/C/C2y/n3370.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,105 @@
// RUN: %clang_cc1 -verify=expected,c-expected -std=c2y -Wall -pedantic %s
// RUN: %clang_cc1 -verify=expected,c-expected,ped -std=c23 -Wall -pedantic %s
// RUN: %clang_cc1 -verify=expected,cxx-expected,gnu -Wall -pedantic -x c++ %s
// RUN: %clang_cc1 -verify=expected,c-expected,pre -std=c2y -Wpre-c2y-compat -Wall -pedantic %s

/* WG14 N3370: Yes
* Case range expressions v3.1
*
* This introduces the ability to specify closed ranges in case statements in a
* switch statement. This was already a well-supported Clang extension before
* it was standardized.
*/

void correct(int i) {
constexpr int j = 100, k = 200;
switch (i) {
case 12 ... 14: break; /* gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
// Implementations are encouraged to diagnose empty ranges.
case 15 ... 11: break; /* expected-warning {{empty case range specified}}
gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
// This is not an empty range, it's a range of a single value.
case 10 ... 10: break; /* gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
case j ... k: break; /* gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
}
}

void incorrect(int i) { // cxx-expected-note 2 {{declared here}}
switch (i) {
// The values have to be integer constant expressions. Note that when the
// initial value in the range is an error, we don't issue the warnings about
// extensions or incompatibility.
case i ... 10: break; /* c-expected-error {{expression is not an integer constant expression}}
cxx-expected-error {{case value is not a constant expression}}
cxx-expected-note {{function parameter 'i' with unknown value cannot be used in a constant expression}}
*/
case 10 ... i: break; /* c-expected-error {{expression is not an integer constant expression}}
cxx-expected-error {{case value is not a constant expression}}
cxx-expected-note {{function parameter 'i' with unknown value cannot be used in a constant expression}}
gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
case 1.3f ... 10: break; /* c-expected-error {{integer constant expression must have integer type, not 'float'}}
cxx-expected-error {{conversion from 'float' to 'int' is not allowed in a converted constant expression}}
*/
case 10 ... "a": break; /* c-expected-error {{integer constant expression must have integer type, not 'char[2]'}}
cxx-expected-error {{value of type 'const char[2]' is not implicitly convertible to 'int'}}
gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
}

switch (i) {
// Cannot have multiple cases covering the same value.
// FIXME: diagnostic quality here is poor. The "previous case" note is
// showing up on a subsequent line (I'd expect the error and note to be
// reversed), and "duplicate case value 20" is showing up on a line where
// there is no duplicate value 20 to begin with.
case 10 ... 20: break; /* expected-error {{duplicate case value '11'}}
expected-note {{previous case defined here}}
gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
case 11: break; /* expected-note {{previous case defined here}}
*/
case 11 ... 14: break; /* expected-error {{duplicate case value '20'}}
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Oh my :)

gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
}

// The values specified by the range shall not change as a result of
// conversion to the promoted type of the controlling expression.
// FIXME: the overflow warnings seem like they probably should also trigger
// in C++ as they do in C.
switch ((unsigned char)i) {
case 254 ... 256: break; /* c-expected-warning {{overflow converting case value to switch condition type (256 to 0)}}
gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
case 257 ... 258: break; /* c-expected-warning {{overflow converting case value to switch condition type (257 to 1)}}
c-expected-warning {{overflow converting case value to switch condition type (258 to 2)}}
gnu-warning {{case ranges are a GNU extension}}
ped-warning {{case ranges are a C2y extension}}
pre-warning {{case ranges are incompatible with C standards before C2y}}
*/
}
}

16 changes: 2 additions & 14 deletions clang/test/Sema/gnu-flags.c
Original file line number Diff line number Diff line change
@@ -1,20 +1,19 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s -DNONE -Wno-gnu
// RUN: %clang_cc1 -fsyntax-only -verify %s -DALL -Wgnu
// RUN: %clang_cc1 -fsyntax-only -verify %s -DALL -Wno-gnu \
// RUN: -Wgnu-alignof-expression -Wgnu-case-range -Wgnu-complex-integer -Wgnu-conditional-omitted-operand \
// RUN: -Wgnu-alignof-expression -Wgnu-complex-integer -Wgnu-conditional-omitted-operand \
// RUN: -Wgnu-label-as-value -Wgnu-statement-expression \
// RUN: -Wgnu-compound-literal-initializer -Wgnu-flexible-array-initializer \
// RUN: -Wgnu-redeclared-enum -Wgnu-folding-constant -Wgnu-empty-struct \
// RUN: -Wgnu-union-cast -Wgnu-variable-sized-type-not-at-end
// RUN: %clang_cc1 -fsyntax-only -verify %s -DNONE -Wgnu \
// RUN: -Wno-gnu-alignof-expression -Wno-gnu-case-range -Wno-gnu-complex-integer -Wno-gnu-conditional-omitted-operand \
// RUN: -Wno-gnu-alignof-expression -Wno-gnu-complex-integer -Wno-gnu-conditional-omitted-operand \
// RUN: -Wno-gnu-label-as-value -Wno-gnu-statement-expression \
// RUN: -Wno-gnu-compound-literal-initializer -Wno-gnu-flexible-array-initializer \
// RUN: -Wno-gnu-redeclared-enum -Wno-gnu-folding-constant -Wno-gnu-empty-struct \
// RUN: -Wno-gnu-union-cast -Wno-gnu-variable-sized-type-not-at-end
// Additional disabled tests:
// %clang_cc1 -fsyntax-only -verify %s -DALIGNOF -Wno-gnu -Wgnu-alignof-expression
// %clang_cc1 -fsyntax-only -verify %s -DCASERANGE -Wno-gnu -Wgnu-case-range
// %clang_cc1 -fsyntax-only -verify %s -DCOMPLEXINT -Wno-gnu -Wgnu-complex-integer
// %clang_cc1 -fsyntax-only -verify %s -DOMITTEDOPERAND -Wno-gnu -Wgnu-conditional-omitted-operand
// %clang_cc1 -fsyntax-only -verify %s -DLABELVALUE -Wno-gnu -Wgnu-label-as-value
Expand All @@ -41,17 +40,6 @@ char align;
_Static_assert(_Alignof(align) > 0, "align's alignment is wrong");


#if ALL || CASERANGE
// expected-warning@+5 {{use of GNU case range extension}}
#endif

void caserange(int x) {
switch (x) {
case 42 ... 44: ;
}
}


#if ALL || COMPLEXINT
// expected-warning@+3 {{complex integer types are a GNU extension}}
#endif
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2 changes: 1 addition & 1 deletion clang/www/c_status.html
Original file line number Diff line number Diff line change
Expand Up @@ -236,7 +236,7 @@ <h2 id="c2y">C2y implementation status</h2>
<tr>
<td>Case range expressions v3.1</td>
<td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3370.htm">N3370</a></td>
<td class="unknown" align="center">Unknown</td>
<td class="full" align="center">Yes</td>
</tr>
<tr>
<td>New _Lengthof() operator (v4)</td>
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