[cfe-commits] r150145 - in /cfe/trunk: include/clang/Basic/DiagnosticASTKinds.td include/clang/Basic/DiagnosticSemaKinds.td lib/AST/DeclCXX.cpp lib/AST/ExprConstant.cpp lib/CodeGen/CGDecl.cpp lib/Sema/SemaType.cpp test/CXX/basic/basic.types/p10.cpp test/SemaCXX/constant-expression-cxx11.cpp
Richard Smith
richard-llvm at metafoo.co.uk
Wed Feb 8 19:29:58 PST 2012
Author: rsmith
Date: Wed Feb 8 21:29:58 2012
New Revision: 150145
URL: http://llvm.org/viewvc/llvm-project?rev=150145&view=rev
Log:
CWG issue 1405: mutable members are allowed in literal types, but can't undergo
lvalue-to-rvalue conversions in constant expressions.
Modified:
cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/AST/DeclCXX.cpp
cfe/trunk/lib/AST/ExprConstant.cpp
cfe/trunk/lib/CodeGen/CGDecl.cpp
cfe/trunk/lib/Sema/SemaType.cpp
cfe/trunk/test/CXX/basic/basic.types/p10.cpp
cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
Modified: cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td Wed Feb 8 21:29:58 2012
@@ -85,6 +85,8 @@
def note_constexpr_ltor_volatile_obj : Note<
"read of volatile %select{temporary|object %1|member %1}0 is not allowed in "
"a constant expression">;
+def note_constexpr_ltor_mutable : Note<
+ "read of mutable member %0 is not allowed in a constant expression">;
def note_constexpr_ltor_non_const_int : Note<
"read of non-const variable %0 is not allowed in a constant expression">;
def note_constexpr_ltor_non_constexpr : Note<
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed Feb 8 21:29:58 2012
@@ -1425,8 +1425,6 @@
"%0 is not literal because it has a user-provided destructor">;
def note_non_literal_nontrivial_dtor : Note<
"%0 is not literal because it has a non-trivial destructor">;
-def note_non_literal_mutable_field : Note<
- "%0 is not literal because it has a mutable data member">;
// C++11 char16_t/char32_t
def warn_cxx98_compat_unicode_type : Warning<
Modified: cfe/trunk/lib/AST/DeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/DeclCXX.cpp?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/lib/AST/DeclCXX.cpp (original)
+++ cfe/trunk/lib/AST/DeclCXX.cpp Wed Feb 8 21:29:58 2012
@@ -800,11 +800,7 @@
}
// Record if this field is the first non-literal field or base.
- // As a slight variation on the standard, we regard mutable members as being
- // non-literal, since mutating a constexpr variable would break C++11
- // constant expression semantics.
- if ((!hasNonLiteralTypeFieldsOrBases() && !T->isLiteralType()) ||
- Field->isMutable())
+ if (!hasNonLiteralTypeFieldsOrBases() && !T->isLiteralType())
data().HasNonLiteralTypeFieldsOrBases = true;
if (Field->hasInClassInitializer()) {
Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Wed Feb 8 21:29:58 2012
@@ -1453,6 +1453,13 @@
O = &O->getArrayFiller();
ObjType = CAT->getElementType();
} else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
+ if (Field->isMutable()) {
+ Info.Diag(E->getExprLoc(), diag::note_constexpr_ltor_mutable, 1)
+ << Field;
+ Info.Note(Field->getLocation(), diag::note_declared_at);
+ return false;
+ }
+
// Next subobject is a class, struct or union field.
RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
if (RD->isUnion()) {
Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp Wed Feb 8 21:29:58 2012
@@ -773,11 +773,15 @@
// emit it as a global instead.
if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
!NRVO && !isByRef && Ty->isLiteralType()) {
- EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
-
- emission.Address = 0; // signal this condition to later callbacks
- assert(emission.wasEmittedAsGlobal());
- return emission;
+ CXXRecordDecl *RD =
+ Ty->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
+ if (!RD || !RD->hasMutableFields()) {
+ EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
+
+ emission.Address = 0; // signal this condition to later callbacks
+ assert(emission.wasEmittedAsGlobal());
+ return emission;
+ }
}
// Otherwise, tell the initialization code that we're in this case.
Modified: cfe/trunk/lib/Sema/SemaType.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaType.cpp?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaType.cpp (original)
+++ cfe/trunk/lib/Sema/SemaType.cpp Wed Feb 8 21:29:58 2012
@@ -4302,9 +4302,6 @@
Diag((*I)->getLocation(), diag::note_non_literal_field)
<< RD << (*I) << (*I)->getType();
return true;
- } else if ((*I)->isMutable()) {
- Diag((*I)->getLocation(), diag::note_non_literal_mutable_field) << RD;
- return true;
}
}
} else if (!RD->hasTrivialDestructor()) {
Modified: cfe/trunk/test/CXX/basic/basic.types/p10.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/basic/basic.types/p10.cpp?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/test/CXX/basic/basic.types/p10.cpp (original)
+++ cfe/trunk/test/CXX/basic/basic.types/p10.cpp Wed Feb 8 21:29:58 2012
@@ -107,21 +107,3 @@
S s[3]; // expected-note {{data member 's' of non-literal type 'S [3]'}}
};
constexpr int f(ArrBad); // expected-error {{1st parameter type 'ArrBad' is not a literal type}}
-
-
-// As a non-conforming tweak to the standard, we do not allow a literal type to
-// have any mutable data members.
-namespace MutableMembers {
- struct MM {
- mutable int n; // expected-note {{'MM' is not literal because it has a mutable data member}}
- };
- constexpr int f(MM); // expected-error {{not a literal type}}
-
- // Here's one reason why allowing this would be a disaster...
- template<int n> struct Id { int k = n; };
- int f() {
- constexpr MM m = { 0 }; // expected-error {{must be initialized by a constant expression}} expected-note {{non-literal type 'const MutableMembers::MM' cannot be used in a constant expression}} expected-note {{here}}
- ++m.n;
- return Id<m.n>().k; // expected-error {{not a constant expression}} expected-note {{initializer of 'm' is not a constant expression}}
- }
-}
Modified: cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp?rev=150145&r1=150144&r2=150145&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp (original)
+++ cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp Wed Feb 8 21:29:58 2012
@@ -1121,6 +1121,30 @@
static_assert(s2.f == 7, "");
}
+// DR1405: don't allow reading mutable members in constant expressions.
+namespace MutableMembers {
+ struct MM {
+ mutable int n; // expected-note 3{{declared here}}
+ } constexpr mm = { 4 };
+ constexpr int mmn = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}}
+ int x = (mm.n = 1, 3);
+ constexpr int mmn2 = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}}
+
+ // Here's one reason why allowing this would be a disaster...
+ template<int n> struct Id { int k = n; };
+ int f() {
+ constexpr MM m = { 0 };
+ ++m.n;
+ return Id<m.n>().k; // expected-error {{not a constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}}
+ }
+
+ struct A { int n; };
+ struct B { mutable A a; }; // expected-note {{here}}
+ struct C { B b; };
+ constexpr C c[3] = {};
+ constexpr int k = c[1].b.a.n; // expected-error {{constant expression}} expected-note {{mutable}}
+}
+
namespace Fold {
// This macro forces its argument to be constant-folded, even if it's not
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