aaron.ballman created this revision.
aaron.ballman added reviewers: rsmith, jyknight.
aaron.ballman requested review of this revision.
I noticed that our diagnostics relating to static assertions are a bit
confused. For instance, when in MS compatibility mode in C (where we accept
`static_assert` even without including `<assert.h>`), we would fail to warn the
user that they were using the wrong spelling (even in pedantic mode), we were
missing a compatibility warning about using `_Static_assert` in earlier
standards modes, diagnostics for the optional message were not reflected in C
as they were in C++, etc.
This patch improves the diagnostic functionality in both C and C++ mode. It
adds `-Wc89-c99-c11-c17-compat` and `-Wc89-c99-c11-c17-compat-pedantic`
diagnostics groups and adds new C-specific diagnostics for a static assertion
without a diagnostic message.
https://reviews.llvm.org/D95396
Files:
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticParseKinds.td
clang/lib/Parse/ParseDeclCXX.cpp
clang/test/Parser/static_assert.c
clang/test/SemaCXX/static-assert.cpp
Index: clang/test/SemaCXX/static-assert.cpp
===================================================================
--- clang/test/SemaCXX/static-assert.cpp
+++ clang/test/SemaCXX/static-assert.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11 -triple=x86_64-linux-gnu
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11 -pedantic -triple=x86_64-linux-gnu
int f(); // expected-note {{declared here}}
Index: clang/test/Parser/static_assert.c
===================================================================
--- /dev/null
+++ clang/test/Parser/static_assert.c
@@ -0,0 +1,45 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c2x -DTEST_SPELLING -verify=c2x %s
+// RUN: %clang_cc1 -fsyntax-only -std=c2x -DTEST_SPELLING -fms-compatibility -verify=c2x-ms %s
+// RUN: %clang_cc1 -fsyntax-only -std=c2x -Wc89-c99-c11-c17-compat -verify=c2x-compat %s
+// RUN: %clang_cc1 -fsyntax-only -std=c99 -verify=c99 %s
+// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic -verify=c99-pedantic %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify=cxx17 -x c++ %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -pedantic -verify=cxx17-pedantic -x c++ %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++98 -verify=cxx98 -x c++ %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++98 -pedantic -verify=cxx98-pedantic -x c++ %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -Wc++98-c++11-c++14-compat -verify=cxx17-compat -x c++ %s
+
+// c99-no-diagnostics
+// cxx17-no-diagnostics
+// cxx98-no-diagnostics
+
+#ifdef TEST_SPELLING
+// Only test the C++ spelling in C mode in some of the tests, to reduce the
+// amount of diagnostics to have to check. This spelling is allowed in MS-
+// compatibility mode in C, but otherwise produces errors.
+static_assert(1, ""); // c2x-error {{expected parameter declarator}} \
+ // c2x-error {{expected ')'}} \
+ // c2x-note {{to match this '('}} \
+ // c2x-warning {{type specifier missing, defaults to 'int'}} \
+ // c2x-ms-warning {{'static_assert' is spelled '_Static_assert' in C; consider including <assert.h>}}
+#endif
+
+// We support _Static_assert as an extension in older C modes and in all C++
+// modes, but only as a pedantic warning.
+_Static_assert(1, ""); // c99-pedantic-warning {{'_Static_assert' is a C11 extension}} \
+ // cxx17-pedantic-warning {{'_Static_assert' is a C11 extension}} \
+ // cxx98-pedantic-warning {{'_Static_assert' is a C11 extension}}
+
+// _Static_assert without a message has more complex diagnostic logic:
+// * In C++17 or C2x mode, it's supported by default.
+// * But there is a special compat warning flag to warn about portability to
+// older standards.
+// * In older standard pedantic modes, warn about supporting without a
+// message as an extension.
+_Static_assert(1); // c99-pedantic-warning {{'_Static_assert' with no message is a C2x extension}} \
+ // cxx98-pedantic-warning {{'static_assert' with no message is a C++17 extension}} \
+ // c2x-compat-warning {{'_Static_assert' with no message is incompatible with C standards before C2x}} \
+ // cxx17-compat-warning {{'static_assert' with no message is incompatible with C++ standards before C++17}} \
+ // c99-pedantic-warning {{'_Static_assert' is a C11 extension}} \
+ // cxx17-pedantic-warning {{'_Static_assert' is a C11 extension}} \
+ // cxx98-pedantic-warning {{'_Static_assert' is a C11 extension}}
Index: clang/lib/Parse/ParseDeclCXX.cpp
===================================================================
--- clang/lib/Parse/ParseDeclCXX.cpp
+++ clang/lib/Parse/ParseDeclCXX.cpp
@@ -871,8 +871,13 @@
if (Tok.is(tok::kw__Static_assert) && !getLangOpts().C11)
Diag(Tok, diag::ext_c11_feature) << Tok.getName();
- if (Tok.is(tok::kw_static_assert))
- Diag(Tok, diag::warn_cxx98_compat_static_assert);
+ if (Tok.is(tok::kw_static_assert)) {
+ if (!getLangOpts().CPlusPlus)
+ Diag(Tok, diag::warn_cxx_static_assert_in_c)
+ << FixItHint::CreateReplacement(Tok.getLocation(), "_Static_assert");
+ else
+ Diag(Tok, diag::warn_cxx98_compat_static_assert);
+ }
SourceLocation StaticAssertLoc = ConsumeToken();
@@ -893,12 +898,19 @@
ExprResult AssertMessage;
if (Tok.is(tok::r_paren)) {
- Diag(Tok, getLangOpts().CPlusPlus17
- ? diag::warn_cxx14_compat_static_assert_no_message
- : diag::ext_static_assert_no_message)
- << (getLangOpts().CPlusPlus17
- ? FixItHint()
- : FixItHint::CreateInsertion(Tok.getLocation(), ", \"\""));
+ unsigned DiagVal;
+ if (getLangOpts().CPlusPlus17)
+ DiagVal = diag::warn_cxx14_compat_static_assert_no_message;
+ else if (getLangOpts().CPlusPlus)
+ DiagVal = diag::ext_cxx_static_assert_no_message;
+ else if (getLangOpts().C2x)
+ DiagVal = diag::warn_c17_compat_static_assert_no_message;
+ else
+ DiagVal = diag::ext_c_static_assert_no_message;
+ Diag(Tok, DiagVal) << ((getLangOpts().CPlusPlus17 || getLangOpts().C2x)
+ ? FixItHint()
+ : FixItHint::CreateInsertion(Tok.getLocation(),
+ ", \"\""));
} else {
if (ExpectAndConsume(tok::comma)) {
SkipUntil(tok::semi);
Index: clang/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticParseKinds.td
+++ clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -424,12 +424,21 @@
def warn_cxx98_compat_static_assert : Warning<
"static_assert declarations are incompatible with C++98">,
InGroup<CXX98Compat>, DefaultIgnore;
-def ext_static_assert_no_message : ExtWarn<
- "static_assert with no message is a C++17 extension">, InGroup<CXX17>;
+def warn_cxx_static_assert_in_c : Warning<
+ "'static_assert' is spelled '_Static_assert' in C; consider including "
+ "<assert.h>">, InGroup<DiagGroup<"static-assert-extension">>;
+def ext_cxx_static_assert_no_message : Extension<
+ "'static_assert' with no message is a C++17 extension">, InGroup<CXX17>;
+def ext_c_static_assert_no_message : Extension<
+ "'_Static_assert' with no message is a C2x extension">, InGroup<C2x>;
def warn_cxx14_compat_static_assert_no_message : Warning<
- "static_assert with no message is incompatible with C++ standards before "
+ "'static_assert' with no message is incompatible with C++ standards before "
"C++17">,
DefaultIgnore, InGroup<CXXPre17Compat>;
+def warn_c17_compat_static_assert_no_message : Warning<
+ "'_Static_assert' with no message is incompatible with C standards before "
+ "C2x">,
+ DefaultIgnore, InGroup<CPre2xCompat>;
def err_function_definition_not_allowed : Error<
"function definition is not allowed here">;
def err_expected_end_of_enumerator : Error<
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -253,6 +253,11 @@
// Name of this warning in GCC.
def NoexceptType : DiagGroup<"noexcept-type", [CXX17CompatMangling]>;
+// Warnings for C2x code which is not compatible with prior C standards.
+def CPre2xCompat : DiagGroup<"c89-c99-c11-c17-compat">;
+def CPre2xCompatPedantic : DiagGroup<"c89-c99-c11-c17-compat-pedantic",
+ [CPre2xCompat]>;
+
// Warnings for C++1y code which is not compatible with prior C++ standards.
def CXXPre14Compat : DiagGroup<"c++98-c++11-compat">;
def CXXPre14CompatPedantic : DiagGroup<"c++98-c++11-compat-pedantic",
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