Generalize typedef-to-void* check in loplugin:redundantcast

...to also cover cases like conversion betwen LPVOID and HANDLE in Windows-only
code

Change-Id: I934fe89372ee7a12462e7ad4284b9ea2cc73ce5a

3 files changed, 74 insertions, 23 deletions

diff --git a/compilerplugins/clang/check.cxx b/compilerplugins/clang/check.cxx
index 33be502c3e1c..43a7edf2bef4 100644
--- a/compilerplugins/clang/check.cxx
+++ b/compilerplugins/clang/check.cxx
@@ -14,6 +14,16 @@
 
 namespace loplugin {
 
+TypeCheck TypeCheck::NonConstVolatile() const {
+    return
+        (!type_.isNull() && !type_.isConstQualified()
+         && !type_.isVolatileQualified())
+        ? *this : TypeCheck();
+        // returning TypeCheck(type_.getUnqualifiedType()) instead of *this
+        // may look tempting, but could remove sugar we might be interested in
+        // checking for
+}
+
 TypeCheck TypeCheck::Const() const {
     return
         (!type_.isNull() && type_.isConstQualified()
@@ -24,6 +34,32 @@ TypeCheck TypeCheck::Const() const {
         // checking for
 }
 
+TypeCheck TypeCheck::Volatile() const {
+    return
+        (!type_.isNull() && !type_.isConstQualified()
+         && type_.isVolatileQualified())
+        ? *this : TypeCheck();
+        // returning TypeCheck(type_.getUnqualifiedType()) instead of *this
+        // may look tempting, but could remove sugar we might be interested in
+        // checking for
+}
+
+TypeCheck TypeCheck::ConstVolatile() const {
+    return
+        (!type_.isNull() && type_.isConstQualified()
+         && type_.isVolatileQualified())
+        ? *this : TypeCheck();
+        // returning TypeCheck(type_.getUnqualifiedType()) instead of *this
+        // may look tempting, but could remove sugar we might be interested in
+        // checking for
+}
+
+TerminalCheck TypeCheck::Void() const {
+    return TerminalCheck(
+        !type_.isNull()
+        && type_->isSpecificBuiltinType(clang::BuiltinType::Void));
+}
+
 TerminalCheck TypeCheck::Char() const {
     return TerminalCheck(
         !type_.isNull()
diff --git a/compilerplugins/clang/check.hxx b/compilerplugins/clang/check.hxx
index 9bfc458354a7..40f205d977fa 100644
--- a/compilerplugins/clang/check.hxx
+++ b/compilerplugins/clang/check.hxx
@@ -35,8 +35,16 @@ public:
 
     explicit operator bool() const { return !type_.isNull(); }
 
+    TypeCheck NonConstVolatile() const;
+
     TypeCheck Const() const;
 
+    TypeCheck Volatile() const;
+
+    TypeCheck ConstVolatile() const;
+
+    TerminalCheck Void() const;
+
     TerminalCheck Char() const;
 
     TerminalCheck AnyBoolean() const;
diff --git a/compilerplugins/clang/redundantcast.cxx b/compilerplugins/clang/redundantcast.cxx
index 5215b39b18e5..6d18f2abffd8 100644
--- a/compilerplugins/clang/redundantcast.cxx
+++ b/compilerplugins/clang/redundantcast.cxx
@@ -291,29 +291,36 @@ bool RedundantCast::VisitCXXStaticCastExpr(CXXStaticCastExpr const * expr) {
     {
         return true;
     }
-    // Don't warn about
-    //
-    //   *pResult = static_cast<oslModule>(RTLD_DEFAULT);
-    //
-    // in osl_getModuleHandle (sal/osl/unx/module.cxx) (where oslModule is a
-    // typedef to void *):
-    if (loplugin::TypeCheck(t2).Typedef("oslModule").GlobalNamespace()
-        && !loplugin::TypeCheck(t1).Typedef())
-    {
-        return true;
-    }
-    // Dont't warn about
-    //
-    //   curl_easy_setopt(static_cast<CURL*>(pData),
-    //                    CURLOPT_HEADERFUNCTION,
-    //                    memory_write_dummy);
-    //
-    // in delete_CURL (ucb/source/ucp/ftp/ftploaderthread.cxx) (where CURL is a
-    // typedef to void):
-    if (loplugin::TypeCheck(t2).Pointer().Typedef("CURL").GlobalNamespace()
-        && !loplugin::TypeCheck(t1).Pointer().Typedef())
-    {
-        return true;
+    // Don't warn if the types are 'void *' and at least one involves a typedef
+    // (and if both involve typedefs, they're different) (this covers cases like
+    // 'oslModule', or 'CURL *', or casts between 'LPVOID' and 'HANDLE' in
+    // Windows-only code):
+    if (loplugin::TypeCheck(t1).Pointer().NonConstVolatile().Void()) {
+        if (auto const td1 = t1->getAs<TypedefType>()) {
+            auto const td2 = t2->getAs<TypedefType>();
+            if (td2 == nullptr || td2 != td1) {
+                return true;
+            }
+        } else if (auto const td2 = t2->getAs<TypedefType>()) {
+            auto const td1 = t1->getAs<TypedefType>();
+            if (td1 == nullptr || td1 != td2) {
+                return true;
+            }
+        } else {
+            auto const pt1 = t1->getAs<clang::PointerType>()->getPointeeType();
+            auto const pt2 = t2->getAs<clang::PointerType>()->getPointeeType();
+            if (auto const ptd1 = pt1->getAs<TypedefType>()) {
+                auto const ptd2 = pt2->getAs<TypedefType>();
+                if (ptd2 == nullptr || ptd2 != ptd1) {
+                    return true;
+                }
+            } else if (auto const ptd2 = pt2->getAs<TypedefType>()) {
+                auto const ptd1 = pt1->getAs<TypedefType>();
+                if (ptd1 == nullptr || ptd1 != ptd2) {
+                    return true;
+                }
+            }
+        }
     }
     report(
         DiagnosticsEngine::Warning,