[Sema] Improve the error diagnostic for dot destructor calls on pointer objects

This commit improves the mismatched destructor type error by detecting when the
destructor call has used a '.' instead of a '->' on a pointer to the destructed
type. The diagnostic now suggests to use '->' instead of '.', and adds a fixit
where appropriate.

rdar://28766702

Differential Revision: https://reviews.llvm.org/D25817

llvm-svn: 292615

5 files changed, 94 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 191bb28df46..2bf1c739395 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -6403,6 +6403,23 @@ static bool CheckArrow(Sema& S, QualType& ObjectType, Expr *&Base,
   return false;
 }
 
+/// \brief Check if it's ok to try and recover dot pseudo destructor calls on
+/// pointer objects.
+static bool
+canRecoverDotPseudoDestructorCallsOnPointerObjects(Sema &SemaRef,
+                                                   QualType DestructedType) {
+  // If this is a record type, check if its destructor is callable.
+  if (auto *RD = DestructedType->getAsCXXRecordDecl()) {
+    if (CXXDestructorDecl *D = SemaRef.LookupDestructor(RD))
+      return SemaRef.CanUseDecl(D, /*TreatUnavailableAsInvalid=*/false);
+    return false;
+  }
+
+  // Otherwise, check if it's a type for which it's valid to use a pseudo-dtor.
+  return DestructedType->isDependentType() || DestructedType->isScalarType() ||
+         DestructedType->isVectorType();
+}
+
 ExprResult Sema::BuildPseudoDestructorExpr(Expr *Base,
                                            SourceLocation OpLoc,
                                            tok::TokenKind OpKind,
@@ -6437,15 +6454,36 @@ ExprResult Sema::BuildPseudoDestructorExpr(Expr *Base,
       = DestructedTypeInfo->getTypeLoc().getLocalSourceRange().getBegin();
     if (!DestructedType->isDependentType() && !ObjectType->isDependentType()) {
       if (!Context.hasSameUnqualifiedType(DestructedType, ObjectType)) {
-        Diag(DestructedTypeStart, diag::err_pseudo_dtor_type_mismatch)
-          << ObjectType << DestructedType << Base->getSourceRange()
-          << DestructedTypeInfo->getTypeLoc().getLocalSourceRange();
-
-        // Recover by setting the destructed type to the object type.
-        DestructedType = ObjectType;
-        DestructedTypeInfo = Context.getTrivialTypeSourceInfo(ObjectType,
-                                                           DestructedTypeStart);
-        Destructed = PseudoDestructorTypeStorage(DestructedTypeInfo);
+        // Detect dot pseudo destructor calls on pointer objects, e.g.:
+        //   Foo *foo;
+        //   foo.~Foo();
+        if (OpKind == tok::period && ObjectType->isPointerType() &&
+            Context.hasSameUnqualifiedType(DestructedType,
+                                           ObjectType->getPointeeType())) {
+          auto Diagnostic =
+              Diag(OpLoc, diag::err_typecheck_member_reference_suggestion)
+              << ObjectType << /*IsArrow=*/0 << Base->getSourceRange();
+
+          // Issue a fixit only when the destructor is valid.
+          if (canRecoverDotPseudoDestructorCallsOnPointerObjects(
+                  *this, DestructedType))
+            Diagnostic << FixItHint::CreateReplacement(OpLoc, "->");
+
+          // Recover by setting the object type to the destructed type and the
+          // operator to '->'.
+          ObjectType = DestructedType;
+          OpKind = tok::arrow;
+        } else {
+          Diag(DestructedTypeStart, diag::err_pseudo_dtor_type_mismatch)
+              << ObjectType << DestructedType << Base->getSourceRange()
+              << DestructedTypeInfo->getTypeLoc().getLocalSourceRange();
+
+          // Recover by setting the destructed type to the object type.
+          DestructedType = ObjectType;
+          DestructedTypeInfo =
+              Context.getTrivialTypeSourceInfo(ObjectType, DestructedTypeStart);
+          Destructed = PseudoDestructorTypeStorage(DestructedTypeInfo);
+        }
       } else if (DestructedType.getObjCLifetime() !=
                                                 ObjectType.getObjCLifetime()) {
 
diff --git a/clang/test/CXX/special/class.dtor/p10-0x.cpp b/clang/test/CXX/special/class.dtor/p10-0x.cpp
index 3b8a0ad4d6a..3be0a98d47d 100644
--- a/clang/test/CXX/special/class.dtor/p10-0x.cpp
+++ b/clang/test/CXX/special/class.dtor/p10-0x.cpp
@@ -33,7 +33,7 @@ void a(const A *x, int i, int *pi) {
                              expected-error{{the type of object expression ('int') does not match the type being destroyed ('decltype(intp())' (aka 'int *')) in pseudo-destructor expression}}
   i.~decltype(intp())(); // expected-error{{the type of object expression ('int') does not match the type being destroyed ('decltype(intp())' (aka 'int *')) in pseudo-destructor expression}}
   pi->~decltype(int())();
-  pi.~decltype(int())(); // expected-error{{the type of object expression ('int *') does not match the type being destroyed ('decltype(int())' (aka 'int')) in pseudo-destructor expression}}
+  pi.~decltype(int())(); // expected-error{{member reference type 'int *' is a pointer; did you mean to use '->'?}}
   pi.~decltype(intp())();
   pi->~decltype(intp())(); // expected-error{{the type of object expression ('int') does not match the type being destroyed ('decltype(intp())' (aka 'int *')) in pseudo-destructor expression}}
 }
diff --git a/clang/test/FixIt/fixit.cpp b/clang/test/FixIt/fixit.cpp
index c43aac98623..0b7fc626ff8 100644
--- a/clang/test/FixIt/fixit.cpp
+++ b/clang/test/FixIt/fixit.cpp
@@ -409,3 +409,14 @@ const const_zero_init czi; // expected-error {{default initialization of an obje
 // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:26-[[@LINE-1]]:26}:"{}"
 int use_czi = czi.a;
 
+namespace dotPointerDestructor {
+
+struct Bar {
+  ~Bar();
+};
+
+void bar(Bar *o) {
+  o.~Bar(); // expected-error {{member reference type 'dotPointerDestructor::Bar *' is a pointer; did you mean to use '->'}}
+}  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:4-[[@LINE-1]]:5}:"->"
+
+}
diff --git a/clang/test/FixIt/no-fixit.cpp b/clang/test/FixIt/no-fixit.cpp
index 7e8e1fbbb07..2dad28d3579 100644
--- a/clang/test/FixIt/no-fixit.cpp
+++ b/clang/test/FixIt/no-fixit.cpp
@@ -11,3 +11,15 @@ struct {
     (void)&i;
   }
 } x;
+
+namespace dotPointerDestructor {
+
+struct Bar {
+  ~Bar() = delete;
+};
+
+void bar(Bar *o) {
+  o.~Bar(); // no fixit
+}
+
+}
diff --git a/clang/test/SemaCXX/pseudo-destructors.cpp b/clang/test/SemaCXX/pseudo-destructors.cpp
index 45f1eafba10..bc0d7b2c835 100644
--- a/clang/test/SemaCXX/pseudo-destructors.cpp
+++ b/clang/test/SemaCXX/pseudo-destructors.cpp
@@ -89,3 +89,26 @@ template<typename T> using Id = T;
 void AliasTemplate(int *p) {
   p->~Id<int>();
 }
+
+namespace dotPointerAccess {
+struct Base {
+  virtual ~Base() {}
+};
+
+struct Derived : Base {
+  ~Derived() {}
+};
+
+void test() {
+  Derived d;
+  static_cast<Base *>(&d).~Base(); // expected-error {{member reference type 'dotPointerAccess::Base *' is a pointer; did you mean to use '->'}}
+  d->~Derived(); // expected-error {{member reference type 'dotPointerAccess::Derived' is not a pointer; did you mean to use '.'}}
+}
+
+typedef Derived *Foo;
+
+void test2(Foo d) {
+  d.~Foo(); // This is ok
+  d.~Derived(); // expected-error {{member reference type 'Foo' (aka 'dotPointerAccess::Derived *') is a pointer; did you mean to use '->'}}
+}
+}