[clang] [C2y] Add test coverage for WG14 N3370 (PR #115054)
Aaron Ballman via cfe-commits
cfe-commits at lists.llvm.org
Wed Nov 6 06:50:01 PST 2024
https://github.com/AaronBallman updated https://github.com/llvm/llvm-project/pull/115054
>From 75706666adf7a47d5a863e399aca38984031387e Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Tue, 5 Nov 2024 15:01:18 -0500
Subject: [PATCH 1/3] [C2y] Add test coverage for WG14 N3370
This paper added case ranges in switch statements, which is a GNU
extension Clang has supported since at least Clang 3.0.
It updates the diagnostics to no longer call this a GNU extension
except in C++ mode.
---
.../clang/Basic/DiagnosticParseKinds.td | 9 +-
clang/lib/Parse/ParseStmt.cpp | 10 +-
clang/test/C/C2y/n3370.c | 105 ++++++++++++++++++
clang/www/c_status.html | 2 +-
4 files changed, 122 insertions(+), 4 deletions(-)
create mode 100644 clang/test/C/C2y/n3370.c
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 78510e61a639fa..0da509280068ad 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -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">;
diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 6470e55e521add..9ba3b112254933 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -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))
diff --git a/clang/test/C/C2y/n3370.c b/clang/test/C/C2y/n3370.c
new file mode 100644
index 00000000000000..0d654fb4ad28b9
--- /dev/null
+++ b/clang/test/C/C2y/n3370.c
@@ -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'}}
+ 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}}
+ */
+ }
+}
+
diff --git a/clang/www/c_status.html b/clang/www/c_status.html
index c896b6124b6ab2..8b677095cee182 100644
--- a/clang/www/c_status.html
+++ b/clang/www/c_status.html
@@ -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>
>From 2ac83500d500d06b3d11ef4ec6e5d0ea9c83ad71 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Wed, 6 Nov 2024 09:46:24 -0500
Subject: [PATCH 2/3] Update gnu-flags.c test
---
clang/test/Sema/gnu-flags.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)
diff --git a/clang/test/Sema/gnu-flags.c b/clang/test/Sema/gnu-flags.c
index 941d7084869dec..1dded9ba67ca40 100644
--- a/clang/test/Sema/gnu-flags.c
+++ b/clang/test/Sema/gnu-flags.c
@@ -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
@@ -41,17 +40,6 @@ char align;
_Static_assert(_Alignof(align) > 0, "align's alignment is wrong");
-#if ALL || CASERANGE
-// expected-warning at +5 {{use of GNU case range extension}}
-#endif
-
-void caserange(int x) {
- switch (x) {
- case 42 ... 44: ;
- }
-}
-
-
#if ALL || COMPLEXINT
// expected-warning at +3 {{complex integer types are a GNU extension}}
#endif
>From 51bec6c5c15c32c8f480b4873e2b06fb687bee6d Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Wed, 6 Nov 2024 09:49:26 -0500
Subject: [PATCH 3/3] Added release note
---
clang/docs/ReleaseNotes.rst | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 4e555914caee8a..7be4780527919c 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -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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