Diagnose implicit member accesses when qualified by a splice.

faisalv · May 25, 2024 · 0994a5a · 0994a5a
1 parent 3d27e82
commit 0994a5a
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Showing 3 changed files with 104 additions and 9 deletions.
diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
@@ -2056,6 +2056,20 @@ Sema::BuildImplicitMemberExpr(const CXXScopeSpec &SS,
 
   SourceLocation loc = R.getNameLoc();
 
+  if (auto *NNS = SS.getScopeRep()) {
+    if (auto *Prefix = NNS->getPrefix())
+      NNS = Prefix;
+
+    if (NNS->getAsSpliceExpr()) {
+      Diag(SS.getBeginLoc(),
+           diag::err_dependent_splice_implicit_member_reference)
+          << SourceRange(SS.getBeginLoc(), R.getNameLoc());
+      Diag(SS.getBeginLoc(),
+           diag::note_dependent_splice_explicit_this_may_fix);
+      return ExprError();
+    }
+  }
+
   // If this is known to be an instance access, go ahead and build an
   // implicit 'this' expression now.
   QualType ThisTy = getCurrentThisType();

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
@@ -14436,26 +14436,46 @@ ExprResult TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
   if (!NameInfo.getName())
     return ExprError();
 
+  bool ScopeHadLeadingSplice = false;
+  if (auto *NNS = E->getQualifier()) {
+    if (auto *Prefix = NNS->getPrefix())
+      NNS = Prefix;
+
+    ScopeHadLeadingSplice = (NNS->getAsSpliceExpr() != nullptr);
+  }
+
+  ExprResult Result;
   if (!E->hasExplicitTemplateArgs()) {
     if (!getDerived().AlwaysRebuild() && QualifierLoc == E->getQualifierLoc() &&
         // Note: it is sufficient to compare the Name component of NameInfo:
         // if name has not changed, DNLoc has not changed either.
         NameInfo.getName() == E->getDeclName())
       return E;
 
-    return getDerived().RebuildDependentScopeDeclRefExpr(
+    Result = getDerived().RebuildDependentScopeDeclRefExpr(
         QualifierLoc, TemplateKWLoc, NameInfo, /*TemplateArgs=*/nullptr,
         IsAddressOfOperand, RecoveryTSI);
+  } else {
+    TemplateArgumentListInfo TransArgs(E->getLAngleLoc(), E->getRAngleLoc());
+    if (getDerived().TransformTemplateArguments(
+            E->getTemplateArgs(), E->getNumTemplateArgs(), TransArgs))
+      return ExprError();
+
+    Result = getDerived().RebuildDependentScopeDeclRefExpr(
+        QualifierLoc, TemplateKWLoc, NameInfo, &TransArgs, IsAddressOfOperand,
+        RecoveryTSI);
   }
 
-  TemplateArgumentListInfo TransArgs(E->getLAngleLoc(), E->getRAngleLoc());
-  if (getDerived().TransformTemplateArguments(
-          E->getTemplateArgs(), E->getNumTemplateArgs(), TransArgs))
+  if (auto *MRE = dyn_cast_or_null<MemberExpr>(Result.get());
+      ScopeHadLeadingSplice && MRE && MRE->isImplicitAccess()) {
+    SemaRef.Diag(E->getExprLoc(),
+                 diag::err_dependent_splice_implicit_member_reference)
+        << E->getSourceRange();
+    SemaRef.Diag(E->getExprLoc(),
+                 diag::note_dependent_splice_explicit_this_may_fix);
     return ExprError();
-
-  return getDerived().RebuildDependentScopeDeclRefExpr(
-      QualifierLoc, TemplateKWLoc, NameInfo, &TransArgs, IsAddressOfOperand,
-      RecoveryTSI);
+  }
+  return Result;
 }
 
 template<typename Derived>

diff --git a/clang/test/Reflection/splice-exprs.cpp b/clang/test/Reflection/splice-exprs.cpp
@@ -8,7 +8,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// RUN: %clang_cc1 %s -std=c++23 -freflection
+// RUN: %clang_cc1 %s -std=c++23 -freflection -verify
 
 using info = decltype(^int);
 
@@ -204,6 +204,67 @@ int dK = d.[:^S::k:];
 
 }  // namespace with_member_access
 
+                         // ===========================
+                         // with_implicit_member_access
+                         // ===========================
+
+namespace with_implicit_member_access {
+
+// Non-dependent case
+struct S {
+  static constexpr int l = 3;
+
+  int k;
+
+  void fn2() { }
+
+  void fn() {
+    static_assert([:^l:] == 3);
+    static_assert([:^S:]::l == 3);
+    (void) this->[:^k:];
+    (void) this->[:^S:]::k;
+    this->[:^fn2:]();
+    this->[:^S:]::fn2();
+
+    (void) [:^k:];  // expected-error {{cannot implicitly reference}} \
+                    // expected-note {{explicit 'this' pointer}}
+    (void) [:^S:]::k;  // expected-error {{cannot implicitly reference}} \
+                       // expected-note {{explicit 'this' pointer}}
+    [:^fn:]();  // expected-error {{cannot implicitly reference}} \
+                // expected-note {{explicit 'this' pointer}}
+    [:^S:]::fn2();  // expected-error {{cannot implicitly reference}} \
+                    // expected-note {{explicit 'this' pointer}}
+  }
+};
+
+// Dependent case
+struct D {
+  static constexpr int l = 3;
+
+  int k;
+
+  void fn2() { }
+
+  template <typename T>
+  void fn() {
+    static_assert([:^T:]::l == 3);
+    (void) this->[:^T:]::l;
+    (void) this->[:^T:]::fn2();
+
+    (void) [:^T:]::k;  // expected-error {{cannot implicitly reference}} \
+                       // expected-note {{explicit 'this' pointer}}
+    [:^T:]::fn2();  // expected-error {{cannot implicitly reference}} \
+                    // expected-note {{explicit 'this' pointer}}
+  }
+};
+
+void runner() {
+    D f = {4};
+    f.fn<D>();  // expected-note {{in instantiation of function template}}
+}
+
+}  // namespace with_implicit_member_access
+
                            // ======================
                            // with_overridden_memfns
                            // ======================