loplugin:unusedfields fix some more false positives

in the write-only analysis

Change-Id: Ic570416e855b8ec38d54f6f6f1adef4819ea53ee

2 files changed, 33 insertions, 2 deletions

diff --git a/compilerplugins/clang/test/unusedfields.cxx b/compilerplugins/clang/test/unusedfields.cxx
index f549a9a37673..d24e6551c660 100644
--- a/compilerplugins/clang/test/unusedfields.cxx
+++ b/compilerplugins/clang/test/unusedfields.cxx
@@ -17,12 +17,27 @@ struct Foo
 
 struct Bar
 // expected-error@-1 {{read m_bar2 [loplugin:unusedfields]}}
+// expected-error@-2 {{read m_bar3 [loplugin:unusedfields]}}
+// expected-error@-3 {{read m_bar4 [loplugin:unusedfields]}}
+// expected-error@-4 {{read m_functionpointer [loplugin:unusedfields]}}
 {
     int m_bar1;
     int m_bar2 = 1;
+    int* m_bar3;
+    int m_bar4;
+    void (*m_functionpointer)(int&);
+    //check that we see reads of fields when referred to via constructor initializer
     Bar(Foo const & foo) : m_bar1(foo.m_foo1) {}
 
-    int bar() { return m_bar2; }
+    int bar1() { return m_bar2; }
+
+    // check that we see reads of fields when operated on via pointer de-ref
+    void bar2() { *m_bar3 = 2; }
+
+    // check that we see reads of field when passed to a function pointer
+    // check that we see read of a field that is a function pointer
+    void bar3() { m_functionpointer(m_bar4); }
+
 };
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/unusedfields.cxx b/compilerplugins/clang/unusedfields.cxx
index df64c987f347..824efa5c41f7 100644
--- a/compilerplugins/clang/unusedfields.cxx
+++ b/compilerplugins/clang/unusedfields.cxx
@@ -261,12 +261,28 @@ bool UnusedFields::VisitMemberExpr( const MemberExpr* memberExpr )
                 break;
         }
         if (isa<CastExpr>(parent) || isa<MemberExpr>(parent) || isa<ParenExpr>(parent) || isa<ParenListExpr>(parent)
-             || isa<ExprWithCleanups>(parent) || isa<UnaryOperator>(parent))
+             || isa<ExprWithCleanups>(parent))
         {
             child = parent;
             auto parentsRange = compiler.getASTContext().getParents(*parent);
             parent = parentsRange.begin() == parentsRange.end() ? nullptr : parentsRange.begin()->get<Stmt>();
         }
+        else if (auto unaryOperator = dyn_cast<UnaryOperator>(parent))
+        {
+            UnaryOperator::Opcode op = unaryOperator->getOpcode();
+            if (op == UO_AddrOf || op == UO_Deref
+                || op == UO_Plus || op == UO_Minus
+                || op == UO_Not || op == UO_LNot
+                || op == UO_PreInc || op == UO_PostInc
+                || op == UO_PreDec || op == UO_PostDec)
+            {
+                bPotentiallyReadFrom = true;
+                break;
+            }
+            child = parent;
+            auto parentsRange = compiler.getASTContext().getParents(*parent);
+            parent = parentsRange.begin() == parentsRange.end() ? nullptr : parentsRange.begin()->get<Stmt>();
+        }
         else if (isa<CaseStmt>(parent))
         {
             bPotentiallyReadFrom = dyn_cast<CaseStmt>(parent)->getLHS() == child