[clang] dd85c6c - [Sema] Add -Wc++11-narrowing-const-reference (#76094)
via cfe-commits
cfe-commits at lists.llvm.org
Fri Dec 22 08:28:11 PST 2023
Author: Fangrui Song
Date: 2023-12-22T11:28:07-05:00
New Revision: dd85c6cce4fc60fa4850770d66f783300a700f3a
URL: https://github.com/llvm/llvm-project/commit/dd85c6cce4fc60fa4850770d66f783300a700f3a
DIFF: https://github.com/llvm/llvm-project/commit/dd85c6cce4fc60fa4850770d66f783300a700f3a.diff
LOG: [Sema] Add -Wc++11-narrowing-const-reference (#76094)
https://github.com/llvm/llvm-project/pull/75332 diagnosed narrowing
involving const reference. Our depot has hundreds if not thousands of
breakages
(https://github.com/llvm/llvm-project/pull/75332#issuecomment-1864757240).
Add a subgroup of -Wc++11-narrowing to help users gradually fix their
issues without regressing the existing -Wc++11-narrowing diagnostics.
Added:
Modified:
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaInit.cpp
clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp
clang/test/SemaCXX/GH63151.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 7cf347e92d9972..6765721ae7002c 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -348,7 +348,8 @@ def CXX98CompatPedantic : DiagGroup<"c++98-compat-pedantic",
CXXPre20CompatPedantic,
CXXPre23CompatPedantic]>;
-def CXX11Narrowing : DiagGroup<"c++11-narrowing">;
+def CXX11NarrowingConstReference : DiagGroup<"c++11-narrowing-const-reference">;
+def CXX11Narrowing : DiagGroup<"c++11-narrowing", [CXX11NarrowingConstReference]>;
def CXX11WarnInconsistentOverrideDestructor :
DiagGroup<"inconsistent-missing-destructor-override">;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index c100041ca400f2..aebb7d9b945c33 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6158,12 +6158,24 @@ def err_illegal_initializer_type : Error<"illegal initializer type %0">;
def ext_init_list_type_narrowing : ExtWarn<
"type %0 cannot be narrowed to %1 in initializer list">,
InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
+// *_narrowing_const_reference diagnostics have the same messages, but are
+// controlled by -Wc++11-narrowing-const-reference for narrowing involving a
+// const reference.
+def ext_init_list_type_narrowing_const_reference : ExtWarn<
+ "type %0 cannot be narrowed to %1 in initializer list">,
+ InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
def ext_init_list_variable_narrowing : ExtWarn<
"non-constant-expression cannot be narrowed from type %0 to %1 in "
"initializer list">, InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
+def ext_init_list_variable_narrowing_const_reference : ExtWarn<
+ "non-constant-expression cannot be narrowed from type %0 to %1 in "
+ "initializer list">, InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
def ext_init_list_constant_narrowing : ExtWarn<
"constant expression evaluates to %0 which cannot be narrowed to type %1">,
InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
+def ext_init_list_constant_narrowing_const_reference : ExtWarn<
+ "constant expression evaluates to %0 which cannot be narrowed to type %1">,
+ InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
def warn_init_list_type_narrowing : Warning<
"type %0 cannot be narrowed to %1 in initializer list in C++11">,
InGroup<CXX11Narrowing>, DefaultIgnore;
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index f768d2726b0a1c..cc9db5ded1149a 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -10411,40 +10411,53 @@ static void DiagnoseNarrowingInInitList(Sema &S,
// No narrowing occurred.
return;
- case NK_Type_Narrowing:
+ case NK_Type_Narrowing: {
// This was a floating-to-integer conversion, which is always considered a
// narrowing conversion even if the value is a constant and can be
// represented exactly as an integer.
- S.Diag(PostInit->getBeginLoc(), NarrowingErrs(S.getLangOpts())
- ? diag::ext_init_list_type_narrowing
- : diag::warn_init_list_type_narrowing)
+ QualType T = EntityType.getNonReferenceType();
+ S.Diag(PostInit->getBeginLoc(),
+ NarrowingErrs(S.getLangOpts())
+ ? (T == EntityType
+ ? diag::ext_init_list_type_narrowing
+ : diag::ext_init_list_type_narrowing_const_reference)
+ : diag::warn_init_list_type_narrowing)
<< PostInit->getSourceRange()
<< PreNarrowingType.getLocalUnqualifiedType()
- << EntityType.getNonReferenceType().getLocalUnqualifiedType();
+ << T.getLocalUnqualifiedType();
break;
+ }
- case NK_Constant_Narrowing:
+ case NK_Constant_Narrowing: {
// A constant value was narrowed.
+ QualType T = EntityType.getNonReferenceType();
S.Diag(PostInit->getBeginLoc(),
NarrowingErrs(S.getLangOpts())
- ? diag::ext_init_list_constant_narrowing
+ ? (T == EntityType
+ ? diag::ext_init_list_constant_narrowing
+ : diag::ext_init_list_constant_narrowing_const_reference)
: diag::warn_init_list_constant_narrowing)
<< PostInit->getSourceRange()
<< ConstantValue.getAsString(S.getASTContext(), ConstantType)
<< EntityType.getNonReferenceType().getLocalUnqualifiedType();
break;
+ }
- case NK_Variable_Narrowing:
+ case NK_Variable_Narrowing: {
// A variable's value may have been narrowed.
+ QualType T = EntityType.getNonReferenceType();
S.Diag(PostInit->getBeginLoc(),
NarrowingErrs(S.getLangOpts())
- ? diag::ext_init_list_variable_narrowing
+ ? (T == EntityType
+ ? diag::ext_init_list_variable_narrowing
+ : diag::ext_init_list_variable_narrowing_const_reference)
: diag::warn_init_list_variable_narrowing)
<< PostInit->getSourceRange()
<< PreNarrowingType.getLocalUnqualifiedType()
<< EntityType.getNonReferenceType().getLocalUnqualifiedType();
break;
}
+ }
SmallString<128> StaticCast;
llvm::raw_svector_ostream OS(StaticCast);
diff --git a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp
index eac9ac0e827982..2bceb3e267790d 100644
--- a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp
+++ b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp
@@ -1,4 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -std=c++11 -triple x86_64-apple-macosx10.6.7 -verify %s
+// The following narrowing does not involve const references, so
+// -Wno-c++11-narrowing-const-reference does not suppress the errors.
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 -triple x86_64-apple-macosx10.6.7 -Wno-c++11-narrowing-const-reference -verify %s
// Verify that narrowing conversions in initializer lists cause errors in C++0x
// mode.
diff --git a/clang/test/SemaCXX/GH63151.cpp b/clang/test/SemaCXX/GH63151.cpp
index 2c7533ed88f3bb..a4d0da0beee217 100644
--- a/clang/test/SemaCXX/GH63151.cpp
+++ b/clang/test/SemaCXX/GH63151.cpp
@@ -1,12 +1,12 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
-
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,narrowing %s
+// RUN: %clang_cc1 -fsyntax-only -Wno-c++11-narrowing-const-reference -verify %s
struct A { A(const unsigned &x) {} };
void foo(int p) {
- A a { -1 }; // expected-error {{constant expression evaluates to -1 which cannot be narrowed to type 'unsigned int'}}
+ A a { -1 }; // narrowing-error {{constant expression evaluates to -1 which cannot be narrowed to type 'unsigned int'}}
A b { 0 };
- A c { p }; // expected-error {{non-constant-expression cannot be narrowed from type 'int' to 'unsigned int' in initializer list}}
- A d { 0.5 }; // expected-error {{type 'double' cannot be narrowed to 'unsigned int' in initializer list}}
+ A c { p }; // narrowing-error {{non-constant-expression cannot be narrowed from type 'int' to 'unsigned int' in initializer list}}
+ A d { 0.5 }; // narrowing-error {{type 'double' cannot be narrowed to 'unsigned int' in initializer list}}
// expected-warning at -1 {{implicit conversion from 'double' to 'unsigned int' changes value from 0.5 to 0}}
}
More information about the cfe-commits
mailing list