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[Clang][Sema] Handle class member access expressions with valid nested-name-specifiers that become invalid after lookup #98167
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@llvm/pr-subscribers-clang Author: Krystian Stasiowski (sdkrystian) ChangesThe following code causes this assert to fail: struct A { };
struct B;
void f(A *x) {
x->B::y; // crash here
} This happens because we only return early from Full diff: https://github.com/llvm/llvm-project/pull/98167.diff 2 Files Affected:
diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
index b7ea24790d361..daa9a4948f66c 100644
--- a/clang/lib/Sema/SemaExprMember.cpp
+++ b/clang/lib/Sema/SemaExprMember.cpp
@@ -789,9 +789,6 @@ ExprResult Sema::BuildMemberReferenceExpr(
ActOnMemberAccessExtraArgs *ExtraArgs) {
LookupResult R(*this, NameInfo, LookupMemberName);
- if (SS.isInvalid())
- return ExprError();
-
// Implicit member accesses.
if (!Base) {
TypoExpr *TE = nullptr;
@@ -826,6 +823,10 @@ ExprResult Sema::BuildMemberReferenceExpr(
BaseType = Base->getType();
}
+ // BuildMemberReferenceExpr expects a valid nested-name-specifier, if any.
+ if (SS.isInvalid())
+ return ExprError();
+
return BuildMemberReferenceExpr(Base, BaseType,
OpLoc, IsArrow, SS, TemplateKWLoc,
FirstQualifierInScope, R, TemplateArgs, S,
@@ -1745,14 +1746,9 @@ static ExprResult LookupMemberExpr(Sema &S, LookupResult &R,
ExprResult Sema::ActOnMemberAccessExpr(Scope *S, Expr *Base,
SourceLocation OpLoc,
- tok::TokenKind OpKind,
- CXXScopeSpec &SS,
+ tok::TokenKind OpKind, CXXScopeSpec &SS,
SourceLocation TemplateKWLoc,
- UnqualifiedId &Id,
- Decl *ObjCImpDecl) {
- if (SS.isSet() && SS.isInvalid())
- return ExprError();
-
+ UnqualifiedId &Id, Decl *ObjCImpDecl) {
// Warn about the explicit constructor calls Microsoft extension.
if (getLangOpts().MicrosoftExt &&
Id.getKind() == UnqualifiedIdKind::IK_ConstructorName)
diff --git a/clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p2.cpp b/clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p2.cpp
new file mode 100644
index 0000000000000..ebdae971a929e
--- /dev/null
+++ b/clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p2.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -verify -Wno-unused %s
+
+struct A {
+ int y;
+};
+
+struct B; // expected-note 4{{forward declaration of 'B'}}
+
+void f(A *a, B *b) {
+ a->B::x; // expected-error {{incomplete type 'B' named in nested name specifier}}
+ a->A::x; // expected-error {{no member named 'x' in 'A'}}
+ a->A::y;
+ b->B::x; // expected-error {{member access into incomplete type 'B'}}
+ b->A::x; // expected-error {{member access into incomplete type 'B'}}
+ b->A::y; // expected-error {{member access into incomplete type 'B'}}
+}
|
…d-name-specifiers that become invalid after lookup
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LGTM but can you add a changelog entry?
Thanks for running this down! |
@cor3ntin This fixes a bug introduced in this release, so I don't believe a release note is needed. |
Reverts: more Sema changes 9e1f1cf [Clang][Sema] Handle class member access expressions with valid nested-name-specifiers that become invalid after lookup (llvm#98167) Change-Id: I80aa10cf856f4854120e2eb7446335403b163b77
…d-name-specifiers that become invalid after lookup (llvm#98167) The following code causes an assert in `SemaExprMember.cpp` on line 981 to fail: ``` struct A { }; struct B; void f(A *x) { x->B::y; // crash here } ``` This happens because we only return early from `BuildMemberReferenceExpr` when the `CXXScopeSpecifier` is invalid _before_ the lookup is performed. Since the lookup may invalidate the `CXXScopeSpecifier` (e.g. if the _nested-name-specifier_ is incomplete), this results in the second `BuildMemberReferenceExpr` overload being called with an invalid `CXXScopeSpecifier`, which causes the assert to fail. This patch moves the early return for invalid `CXXScopeSpecifiers` to occur _after_ lookup is performed. This fixes llvm#92972. I also removed the `if (SS.isSet() && SS.isInvalid())` check in `ActOnMemberAccessExpr` because the condition can never be true (`isSet` returns `getScopeRep() != nullptr` and `isInvalid` returns `Range.isValid() && getScopeRep() == nullptr`).
cherry-picked: 9e1f1cf [email protected] Tue Jul 9 16:40:53 2024 -0400 [Clang][Sema] Handle class member access expressions with valid nested-name-specifiers that become invalid after lookup (llvm#98167) 584e431 [email protected] Wed Jul 3 12:12:53 2024 -0400 [Clang][Sema] Treat explicit specializations of static data member templates declared without 'static' as static data members when diagnosing uses of 'auto' (llvm#97425) a1bce0b [email protected] Thu Jun 27 08:17:40 2024 -0700 Clang: Add warning flag for storage class specifiers on explicit specializations (llvm#96699) f46d146 [email protected] Fri May 31 11:02:21 2024 -0700 [clang] require template arg list after template kw (llvm#80801) 033ec09 [email protected] Fri Dec 22 09:00:41 2023 +0800 [Clang][Sema] Fix Wswitch-default bad warning in template (llvm#76007) c281782 [email protected] Thu Dec 7 09:03:15 2023 +0800 [clang][Sema] Add -Wswitch-default warning option (llvm#73077) Change-Id: Ib2582201b01cc62c3bf62011347925556e8531f7
The following code causes this assert to fail:
This happens because we only return early from
BuildMemberReferenceExpr
when theCXXScopeSpecifier
is invalid before the lookup is performed. Since the lookup may invalidate theCXXScopeSpecifier
(e.g. if the nested-name-specifier is incomplete), this results in the secondBuildMemberReferenceExpr
overload being called with an invalidCXXScopeSpecifier
, which causes the assert to fail. This patch moves the early return for invalidCXXScopeSpecifiers
to occur after lookup is performed. This fixes #92972.I also removed the
if (SS.isSet() && SS.isInvalid())
check inActOnMemberAccessExpr
because the condition can never be true (isSet
returnsgetScopeRep() != nullptr
andisInvalid
returnsRange.isValid() && getScopeRep() == nullptr
).