loplugin:redundantcast: cstyle_cast within reinterpret_cast

Change-Id: Ie31c9dd6d8741aa856553b798bb5b7f695a3fe0f
Reviewed-on: https://gerrit.libreoffice.org/42776
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/compilerplugins/clang/redundantcast.cxx b/compilerplugins/clang/redundantcast.cxx
index dba573387743..30914a460dc4 100644
--- a/compilerplugins/clang/redundantcast.cxx
+++ b/compilerplugins/clang/redundantcast.cxx
@@ -522,6 +522,20 @@ bool RedundantCast::VisitCXXReinterpretCastExpr(
             expr->getExprLoc())
             << expr->getSubExprAsWritten()->getType() << expr->getType()
             << expr->getSourceRange();
+    } else if (expr->getType()->isFundamentalType()) {
+        if (auto const sub = dyn_cast<CXXConstCastExpr>(
+                expr->getSubExpr()->IgnoreParens()))
+        {
+            report(
+                DiagnosticsEngine::Warning,
+                ("redundant const_cast from %0 to %1 within reinterpret_cast to"
+                 " fundamental type %2"),
+                expr->getExprLoc())
+                << sub->getSubExprAsWritten()->getType()
+                << sub->getTypeAsWritten() << expr->getTypeAsWritten()
+                << expr->getSourceRange();
+            return true;
+        }
     }
     return true;
 }
diff --git a/compilerplugins/clang/test/redundantcast.cxx b/compilerplugins/clang/test/redundantcast.cxx
index 5a56ec42e32e..ff3e8392906a 100644
--- a/compilerplugins/clang/test/redundantcast.cxx
+++ b/compilerplugins/clang/test/redundantcast.cxx
@@ -7,6 +7,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+#include <cstddef>
+
 #include "redundantcast.hxx"
 
 void f1(char *) {}
@@ -318,12 +320,18 @@ void testArithmeticTypedefs() {
     (void) (T1) nt1r(); // expected-error {{redundant}}
 }
 
+void testReinterpretConstCast() {
+    int n = 0;
+    (void) reinterpret_cast<std::size_t>((const_cast<int const *>(&n))); // expected-error-re {{redundant const_cast from 'int *' to 'const int *' within reinterpret_cast to fundamental type 'std::size_t' (aka 'unsigned {{.+}}') [loplugin:redundantcast]}}
+}
+
 int main() {
     testConstCast();
     testStaticCast();
     testFunctionalCast();
     testCStyleCast();
     testCStyleCastOfTemplateMethodResult(nullptr);
+    testReinterpretConstCast();
 }
 
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