Extract loplugin:redundantcast from loplugin:cstylecast

Change-Id: I08f17dd9cc092206083ff41bbbc178e0322e86d0

2 files changed, 84 insertions, 28 deletions

diff --git a/compilerplugins/clang/cstylecast.cxx b/compilerplugins/clang/cstylecast.cxx
index b6bb453127c0..9775a0875ee5 100644
--- a/compilerplugins/clang/cstylecast.cxx
+++ b/compilerplugins/clang/cstylecast.cxx
@@ -47,8 +47,6 @@ public:
 
     bool VisitCStyleCastExpr(const CStyleCastExpr * expr);
 
-    bool VisitImplicitCastExpr(ImplicitCastExpr const * expr);
-
 private:
     bool externCFunction;
 };
@@ -135,32 +133,6 @@ bool CStyleCast::VisitCStyleCastExpr(const CStyleCastExpr * expr) {
     return true;
 }
 
-bool CStyleCast::VisitImplicitCastExpr(const ImplicitCastExpr * expr) {
-    if (ignoreLocation(expr) || expr->getCastKind() != CK_BitCast) {
-        return true;
-    }
-    QualType t = expr->getType();
-    if (!(t->isPointerType()
-          && t->getAs<PointerType>()->getPointeeType()->isVoidType()
-          && expr->getSubExpr()->getType()->isPointerType()))
-    {
-        return true;
-    }
-    Expr const * e = expr->getSubExpr()->IgnoreParenImpCasts();
-    while (isa<CXXConstCastExpr>(e)) {
-        e = dyn_cast<CXXConstCastExpr>(e)->getSubExpr()->IgnoreParenImpCasts();
-    }
-    if (isa<CXXReinterpretCastExpr>(e)) {
-        report(
-            DiagnosticsEngine::Warning,
-            ("redundant reinterpret_cast, result is implicitly cast to void"
-             " pointer"),
-            e->getExprLoc())
-            << e->getSourceRange();
-    }
-    return true;
-}
-
 loplugin::Plugin::Registration< CStyleCast > X("cstylecast");
 
 }
diff --git a/compilerplugins/clang/redundantcast.cxx b/compilerplugins/clang/redundantcast.cxx
new file mode 100644
index 000000000000..e2f61792a55a
--- /dev/null
+++ b/compilerplugins/clang/redundantcast.cxx
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+// Warn about certain redundant casts:
+//
+// * A reinterpret_cast<T*>(...) whose result is then implicitly cast to a void
+//   pointer
+//
+// * A static_cast<T*>(e) where e is of void pointer type and whose result is
+//   then implicitly cast to a void pointer
+//
+// C-style casts are ignored because it makes this plugin simpler, and they
+// should eventually be eliminated via loplugin:cstylecast and/or
+// -Wold-style-cast.  That implies that this plugin is only relevant for C++
+// code.
+
+#include "plugin.hxx"
+
+namespace {
+
+bool isVoidPointer(QualType type) {
+    return type->isPointerType()
+        && type->getAs<PointerType>()->getPointeeType()->isVoidType();
+}
+
+class RedundantCast:
+    public RecursiveASTVisitor<RedundantCast>, public loplugin::Plugin
+{
+public:
+    explicit RedundantCast(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override {
+        if (compiler.getLangOpts().CPlusPlus) {
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+        }
+    }
+
+    bool VisitImplicitCastExpr(ImplicitCastExpr const * expr);
+};
+
+bool RedundantCast::VisitImplicitCastExpr(const ImplicitCastExpr * expr) {
+    if (ignoreLocation(expr) || expr->getCastKind() != CK_BitCast
+        || !isVoidPointer(expr->getType())
+        || !expr->getSubExpr()->getType()->isPointerType())
+    {
+        return true;
+    }
+    Expr const * e = expr->getSubExpr()->IgnoreParenImpCasts();
+    while (isa<CXXConstCastExpr>(e)) {
+        e = dyn_cast<CXXConstCastExpr>(e)->getSubExpr()->IgnoreParenImpCasts();
+    }
+    if (isa<CXXReinterpretCastExpr>(e)) {
+        report(
+            DiagnosticsEngine::Warning,
+            ("redundant reinterpret_cast, result is implicitly cast to void"
+             " pointer"),
+            e->getExprLoc())
+            << e->getSourceRange();
+    } else if (isa<CXXStaticCastExpr>(e)
+               && isVoidPointer(
+                   dyn_cast<CXXStaticCastExpr>(e)->getSubExpr()
+                   ->IgnoreParenImpCasts()->getType()))
+    {
+        report(
+            DiagnosticsEngine::Warning,
+            ("redundant static_cast from void pointer, result is implicitly"
+             " cast to void pointer"),
+            e->getExprLoc())
+            << e->getSourceRange();
+    }
+    return true;
+}
+
+loplugin::Plugin::Registration<RedundantCast> X("redundantcast");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */