[PATCH] D20054: Fix spurious warnings about unused private field

[Olivier Goffart via cfe-commits]

ogoffart created this revision.
ogoffart added reviewers: cfe-commits, djasper.

If the address of a field is taken as a pointer to member, we should
not warn that the field is not used.
    
Normaly, yse of fields are done from MemberExpr, but in case of pointer to
 member, it is in a DeclRefExpr


http://reviews.llvm.org/D20054

Files:
  lib/Sema/SemaExpr.cpp
  test/SemaCXX/warn-unused-private-field.cpp

Index: test/SemaCXX/warn-unused-private-field.cpp
===================================================================
--- test/SemaCXX/warn-unused-private-field.cpp
+++ test/SemaCXX/warn-unused-private-field.cpp
@@ -128,6 +128,7 @@
     int *use = &by_reference_;
     int test[2];
     test[as_array_index_] = 42;
+    int EverythingUsed::*ptr = &EverythingUsed::by_pointer_to_member_;
   }
 
   template<class T>
@@ -142,6 +143,7 @@
   int by_template_function_;
   int as_array_index_;
   int by_initializer_;
+  int by_pointer_to_member_;
 };
 
 class HasFeatureTest {
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -1736,10 +1736,12 @@
       !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, E->getLocStart()))
       recordUseOfEvaluatedWeak(E);
 
-  // Just in case we're building an illegal pointer-to-member.
-  FieldDecl *FD = dyn_cast<FieldDecl>(D);
-  if (FD && FD->isBitField())
-    E->setObjectKind(OK_BitField);
+  if (FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
+    UnusedPrivateFields.remove(FD);
+    // Just in case we're building an illegal pointer-to-member.
+    if (FD->isBitField())
+      E->setObjectKind(OK_BitField);
+  }
 
   return E;
 }



Index: test/SemaCXX/warn-unused-private-field.cpp
===================================================================
--- test/SemaCXX/warn-unused-private-field.cpp
+++ test/SemaCXX/warn-unused-private-field.cpp
@@ -128,6 +128,7 @@
     int *use = &by_reference_;
     int test[2];
     test[as_array_index_] = 42;
+    int EverythingUsed::*ptr = &EverythingUsed::by_pointer_to_member_;
   }
 
   template<class T>
@@ -142,6 +143,7 @@
   int by_template_function_;
   int as_array_index_;
   int by_initializer_;
+  int by_pointer_to_member_;
 };
 
 class HasFeatureTest {
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -1736,10 +1736,12 @@
       !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, E->getLocStart()))
       recordUseOfEvaluatedWeak(E);
 
-  // Just in case we're building an illegal pointer-to-member.
-  FieldDecl *FD = dyn_cast<FieldDecl>(D);
-  if (FD && FD->isBitField())
-    E->setObjectKind(OK_BitField);
+  if (FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
+    UnusedPrivateFields.remove(FD);
+    // Just in case we're building an illegal pointer-to-member.
+    if (FD->isBitField())
+      E->setObjectKind(OK_BitField);
+  }
 
   return E;
 }

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