...and re-eanble loplugin:stringcopy again

<http://reviews.llvm.org/D22128> "Make CastExpr::getSubExprAsWritten look
through implicit temporary under CK_ConstructorConversion" was biting me again.
(I had originally developed loplugin:stringcopy against a Clang build that
includes my local fix for that issue.  I really need to see to get that resolved
upstream...)

(And while 957874168491f4b030fda85c65dd969aae82a670 "loplugin:stringcopy" was
actually a false positive, it doesn't hurt either, so just keep it.)

Change-Id: I726956adfbe67681005173cfdfed2e4b4cd6253d

3 files changed, 79 insertions, 76 deletions

diff --git a/compilerplugins/clang/compat.hxx b/compilerplugins/clang/compat.hxx
index 28dbeec71e20..a493cdc7b209 100644
--- a/compilerplugins/clang/compat.hxx
+++ b/compilerplugins/clang/compat.hxx
@@ -17,6 +17,7 @@
 #include "clang/AST/DeclBase.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticIDs.h"
@@ -244,6 +245,78 @@ inline bool isStdNamespace(clang::DeclContext const & context) {
 #endif
 }
 
+// Work around <http://reviews.llvm.org/D22128>:
+//
+// SfxErrorHandler::GetClassString (svtools/source/misc/ehdl.cxx):
+//
+//   ErrorResource_Impl aEr(aId, (sal_uInt16)lClassId);
+//   if(aEr)
+//   {
+//       rStr = static_cast<ResString>(aEr).GetString();
+//   }
+//
+// expr->dump():
+//  CXXStaticCastExpr 0x2b74e8e657b8 'class ResString' static_cast<class ResString> <ConstructorConversion>
+//  `-CXXBindTemporaryExpr 0x2b74e8e65798 'class ResString' (CXXTemporary 0x2b74e8e65790)
+//    `-CXXConstructExpr 0x2b74e8e65758 'class ResString' 'void (class ResString &&) noexcept(false)' elidable
+//      `-MaterializeTemporaryExpr 0x2b74e8e65740 'class ResString' xvalue
+//        `-CXXBindTemporaryExpr 0x2b74e8e65720 'class ResString' (CXXTemporary 0x2b74e8e65718)
+//          `-ImplicitCastExpr 0x2b74e8e65700 'class ResString' <UserDefinedConversion>
+//            `-CXXMemberCallExpr 0x2b74e8e656d8 'class ResString'
+//              `-MemberExpr 0x2b74e8e656a0 '<bound member function type>' .operator ResString 0x2b74e8dc1f00
+//                `-DeclRefExpr 0x2b74e8e65648 'struct ErrorResource_Impl' lvalue Var 0x2b74e8e653b0 'aEr' 'struct ErrorResource_Impl'
+// expr->getSubExprAsWritten()->dump():
+//  MaterializeTemporaryExpr 0x2b74e8e65740 'class ResString' xvalue
+//  `-CXXBindTemporaryExpr 0x2b74e8e65720 'class ResString' (CXXTemporary 0x2b74e8e65718)
+//    `-ImplicitCastExpr 0x2b74e8e65700 'class ResString' <UserDefinedConversion>
+//      `-CXXMemberCallExpr 0x2b74e8e656d8 'class ResString'
+//        `-MemberExpr 0x2b74e8e656a0 '<bound member function type>' .operator ResString 0x2b74e8dc1f00
+//          `-DeclRefExpr 0x2b74e8e65648 'struct ErrorResource_Impl' lvalue Var 0x2b74e8e653b0 'aEr' 'struct ErrorResource_Impl'
+//
+// Copies code from Clang's lib/AST/Expr.cpp:
+namespace detail {
+  inline clang::Expr *skipImplicitTemporary(clang::Expr *expr) {
+    // Skip through reference binding to temporary.
+    if (clang::MaterializeTemporaryExpr *Materialize
+                                  = clang::dyn_cast<clang::MaterializeTemporaryExpr>(expr))
+      expr = Materialize->GetTemporaryExpr();
+
+    // Skip any temporary bindings; they're implicit.
+    if (clang::CXXBindTemporaryExpr *Binder = clang::dyn_cast<clang::CXXBindTemporaryExpr>(expr))
+      expr = Binder->getSubExpr();
+
+    return expr;
+  }
+}
+inline clang::Expr *getSubExprAsWritten(clang::CastExpr *This) {
+  clang::Expr *SubExpr = nullptr;
+  clang::CastExpr *E = This;
+  do {
+    SubExpr = detail::skipImplicitTemporary(E->getSubExpr());
+
+    // Conversions by constructor and conversion functions have a
+    // subexpression describing the call; strip it off.
+    if (E->getCastKind() == clang::CK_ConstructorConversion)
+      SubExpr =
+        detail::skipImplicitTemporary(clang::cast<clang::CXXConstructExpr>(SubExpr)->getArg(0));
+    else if (E->getCastKind() == clang::CK_UserDefinedConversion) {
+      assert((clang::isa<clang::CXXMemberCallExpr>(SubExpr) ||
+              clang::isa<clang::BlockExpr>(SubExpr)) &&
+             "Unexpected SubExpr for CK_UserDefinedConversion.");
+      if (clang::isa<clang::CXXMemberCallExpr>(SubExpr))
+        SubExpr = clang::cast<clang::CXXMemberCallExpr>(SubExpr)->getImplicitObjectArgument();
+    }
+
+    // If the subexpression we're left with is an implicit cast, look
+    // through that, too.
+  } while ((E = clang::dyn_cast<clang::ImplicitCastExpr>(SubExpr)));
+
+  return SubExpr;
+}
+inline const clang::Expr *getSubExprAsWritten(const clang::CastExpr *This) {
+  return getSubExprAsWritten(const_cast<clang::CastExpr *>(This));
+}
+
 }
 
 #endif
diff --git a/compilerplugins/clang/redundantcast.cxx b/compilerplugins/clang/redundantcast.cxx
index b7fbfd3c9010..3c38dd3ef495 100644
--- a/compilerplugins/clang/redundantcast.cxx
+++ b/compilerplugins/clang/redundantcast.cxx
@@ -26,82 +26,11 @@
 #include "clang/Sema/Sema.h"
 
 #include "check.hxx"
+#include "compat.hxx"
 #include "plugin.hxx"
 
 namespace {
 
-// Work around <http://reviews.llvm.org/D22128>:
-//
-// SfxErrorHandler::GetClassString (svtools/source/misc/ehdl.cxx):
-//
-//   ErrorResource_Impl aEr(aId, (sal_uInt16)lClassId);
-//   if(aEr)
-//   {
-//       rStr = static_cast<ResString>(aEr).GetString();
-//   }
-//
-// expr->dump():
-//  CXXStaticCastExpr 0x2b74e8e657b8 'class ResString' static_cast<class ResString> <ConstructorConversion>
-//  `-CXXBindTemporaryExpr 0x2b74e8e65798 'class ResString' (CXXTemporary 0x2b74e8e65790)
-//    `-CXXConstructExpr 0x2b74e8e65758 'class ResString' 'void (class ResString &&) noexcept(false)' elidable
-//      `-MaterializeTemporaryExpr 0x2b74e8e65740 'class ResString' xvalue
-//        `-CXXBindTemporaryExpr 0x2b74e8e65720 'class ResString' (CXXTemporary 0x2b74e8e65718)
-//          `-ImplicitCastExpr 0x2b74e8e65700 'class ResString' <UserDefinedConversion>
-//            `-CXXMemberCallExpr 0x2b74e8e656d8 'class ResString'
-//              `-MemberExpr 0x2b74e8e656a0 '<bound member function type>' .operator ResString 0x2b74e8dc1f00
-//                `-DeclRefExpr 0x2b74e8e65648 'struct ErrorResource_Impl' lvalue Var 0x2b74e8e653b0 'aEr' 'struct ErrorResource_Impl'
-// expr->getSubExprAsWritten()->dump():
-//  MaterializeTemporaryExpr 0x2b74e8e65740 'class ResString' xvalue
-//  `-CXXBindTemporaryExpr 0x2b74e8e65720 'class ResString' (CXXTemporary 0x2b74e8e65718)
-//    `-ImplicitCastExpr 0x2b74e8e65700 'class ResString' <UserDefinedConversion>
-//      `-CXXMemberCallExpr 0x2b74e8e656d8 'class ResString'
-//        `-MemberExpr 0x2b74e8e656a0 '<bound member function type>' .operator ResString 0x2b74e8dc1f00
-//          `-DeclRefExpr 0x2b74e8e65648 'struct ErrorResource_Impl' lvalue Var 0x2b74e8e653b0 'aEr' 'struct ErrorResource_Impl'
-//
-// Copies code from Clang's lib/AST/Expr.cpp:
-namespace {
-  Expr *skipImplicitTemporary(Expr *expr) {
-    // Skip through reference binding to temporary.
-    if (MaterializeTemporaryExpr *Materialize
-                                  = dyn_cast<MaterializeTemporaryExpr>(expr))
-      expr = Materialize->GetTemporaryExpr();
-
-    // Skip any temporary bindings; they're implicit.
-    if (CXXBindTemporaryExpr *Binder = dyn_cast<CXXBindTemporaryExpr>(expr))
-      expr = Binder->getSubExpr();
-
-    return expr;
-  }
-}
-Expr *getSubExprAsWritten(CastExpr *This) {
-  Expr *SubExpr = nullptr;
-  CastExpr *E = This;
-  do {
-    SubExpr = skipImplicitTemporary(E->getSubExpr());
-
-    // Conversions by constructor and conversion functions have a
-    // subexpression describing the call; strip it off.
-    if (E->getCastKind() == CK_ConstructorConversion)
-      SubExpr =
-        skipImplicitTemporary(cast<CXXConstructExpr>(SubExpr)->getArg(0));
-    else if (E->getCastKind() == CK_UserDefinedConversion) {
-      assert((isa<CXXMemberCallExpr>(SubExpr) ||
-              isa<BlockExpr>(SubExpr)) &&
-             "Unexpected SubExpr for CK_UserDefinedConversion.");
-      if (isa<CXXMemberCallExpr>(SubExpr))
-        SubExpr = cast<CXXMemberCallExpr>(SubExpr)->getImplicitObjectArgument();
-    }
-
-    // If the subexpression we're left with is an implicit cast, look
-    // through that, too.
-  } while ((E = dyn_cast<ImplicitCastExpr>(SubExpr)));
-
-  return SubExpr;
-}
-const Expr *getSubExprAsWritten(const CastExpr *This) {
-  return getSubExprAsWritten(const_cast<CastExpr *>(This));
-}
-
 bool isVoidPointer(QualType type) {
     return type->isPointerType()
         && type->getAs<clang::PointerType>()->getPointeeType()->isVoidType();
@@ -322,7 +251,7 @@ bool RedundantCast::VisitCStyleCastExpr(CStyleCastExpr const * expr) {
     if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(expr->getLocStart()))) {
         return true;
     }
-    auto t1 = getSubExprAsWritten(expr)->getType();
+    auto t1 = compat::getSubExprAsWritten(expr)->getType();
     auto t2 = expr->getTypeAsWritten();
     if (t1 != t2) {
         return true;
@@ -386,7 +315,7 @@ bool RedundantCast::VisitCXXStaticCastExpr(CXXStaticCastExpr const * expr) {
     if (ignoreLocation(expr)) {
         return true;
     }
-    auto t1 = getSubExprAsWritten(expr)->getType();
+    auto t1 = compat::getSubExprAsWritten(expr)->getType();
     auto t2 = expr->getTypeAsWritten();
     if (t1.getCanonicalType() != t2.getCanonicalType()) {
         return true;
diff --git a/compilerplugins/clang/stringcopy.cxx b/compilerplugins/clang/stringcopy.cxx
index c572b965bb9a..b1d8e22216ec 100644
--- a/compilerplugins/clang/stringcopy.cxx
+++ b/compilerplugins/clang/stringcopy.cxx
@@ -8,6 +8,7 @@
  */
 
 #include "check.hxx"
+#include "compat.hxx"
 #include "plugin.hxx"
 
 namespace {
@@ -23,7 +24,7 @@ public:
             return true;
         }
         auto const t1 = expr->getTypeAsWritten();
-        auto const t2 = expr->getSubExprAsWritten()->getType();
+        auto const t2 = compat::getSubExprAsWritten(expr)->getType();
         if ((t1.getCanonicalType().getTypePtr()
              != t2.getCanonicalType().getTypePtr())
             || !(loplugin::TypeCheck(t1).Class("OUString").Namespace("rtl")
@@ -46,7 +47,7 @@ private:
     }
 };
 
-static loplugin::Plugin::Registration<Visitor> reg("stringcopy", false);
+static loplugin::Plugin::Registration<Visitor> reg("stringcopy");
 
 }