loplugin:referencecasting find more redundant static_cast

Change-Id: I3a51812bbd3fcdc6b11e47cb12962f0d4fa7a2ae
Reviewed-on: https://gerrit.libreoffice.org/78191
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 50 insertions, 0 deletions

diff --git a/compilerplugins/clang/plugin.cxx b/compilerplugins/clang/plugin.cxx
index 7e8dfb664b15..bf48e8822a03 100644
--- a/compilerplugins/clang/plugin.cxx
+++ b/compilerplugins/clang/plugin.cxx
@@ -697,6 +697,56 @@ bool hasCLanguageLinkageType(FunctionDecl const * decl) {
     return false;
 }
 
+static const CXXRecordDecl* stripTypeSugar(QualType qt)
+{
+    const clang::Type* t = qt.getTypePtr();
+    while (auto elaboratedType = dyn_cast<ElaboratedType>(t))
+        t = elaboratedType->desugar().getTypePtr();
+    auto recordType = dyn_cast<RecordType>(t);
+    if (!recordType)
+        return nullptr;
+    return dyn_cast_or_null<CXXRecordDecl>(recordType->getDecl());
+}
+
+int derivedFromCount(const CXXRecordDecl* subclassRecordDecl, const CXXRecordDecl* baseclassRecordDecl)
+{
+    if (!subclassRecordDecl || !baseclassRecordDecl)
+        return 0;
+    int derivedCount = 0;
+    if (subclassRecordDecl == baseclassRecordDecl)
+        derivedCount++;
+    if (!subclassRecordDecl->hasDefinition())
+        return derivedCount;
+    for (auto it = subclassRecordDecl->bases_begin(); it != subclassRecordDecl->bases_end(); ++it)
+    {
+        derivedCount += derivedFromCount(stripTypeSugar(it->getType()), baseclassRecordDecl);
+        // short-circuit, we only care about 0,1,2
+        if (derivedCount > 1)
+            return derivedCount;
+    }
+    for (auto it = subclassRecordDecl->vbases_begin(); it != subclassRecordDecl->vbases_end(); ++it)
+    {
+        derivedCount += derivedFromCount(stripTypeSugar(it->getType()), baseclassRecordDecl);
+        // short-circuit, we only care about 0,1,2
+        if (derivedCount > 1)
+            return derivedCount;
+    }
+    return derivedCount;
+}
+
+int derivedFromCount(QualType subclassQt, QualType baseclassQt)
+{
+    auto baseclassRecordDecl = stripTypeSugar(baseclassQt);
+    if (!baseclassRecordDecl)
+        return 0;
+    auto subclassRecordDecl = stripTypeSugar(subclassQt);
+    if (!subclassRecordDecl)
+        return 0;
+
+    return derivedFromCount(subclassRecordDecl, baseclassRecordDecl);
+}
+
+
 } // namespace
 
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