Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 232 insertions, 0 deletions

diff --git a/compilerplugins/clang/unsignedcompare.cxx b/compilerplugins/clang/unsignedcompare.cxx
new file mode 100644
index 000000000..5b55edea2
--- /dev/null
+++ b/compilerplugins/clang/unsignedcompare.cxx
@@ -0,0 +1,232 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * 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/.
+ */
+
+#ifndef LO_CLANG_SHARED_PLUGINS
+
+// Find explicit casts from signed to unsigned integer in comparison against unsigned integer, where
+// the cast is presumably used to avoid warnings about signed vs. unsigned comparisons, and could
+// thus be replaced with o3tl::make_unsigned for clarity.
+
+#include <cassert>
+
+#include "plugin.hxx"
+
+namespace
+{
+// clang::Type::isSignedIntegerType returns true for more types than what C++ defines as signed
+// integer types:
+bool isSignedIntegerType(QualType type)
+{
+    if (auto const t = type->getAs<BuiltinType>())
+    {
+        // Assumes that the only extended signed integer type supported by Clang is Int128:
+        switch (t->getKind())
+        {
+            case BuiltinType::SChar:
+            case BuiltinType::Short:
+            case BuiltinType::Int:
+            case BuiltinType::Long:
+            case BuiltinType::LongLong:
+            case BuiltinType::Int128:
+                return true;
+            default:
+                break;
+        }
+    }
+    return false;
+}
+
+// clang::Type::isUnsignedIntegerType returns true for more types than what C++ defines as signed
+// integer types:
+bool isUnsignedIntegerType(QualType type)
+{
+    if (auto const t = type->getAs<BuiltinType>())
+    {
+        // Assumes that the only extended unsigned integer type supported by Clang is UInt128:
+        switch (t->getKind())
+        {
+            case BuiltinType::UChar:
+            case BuiltinType::UShort:
+            case BuiltinType::UInt:
+            case BuiltinType::ULong:
+            case BuiltinType::ULongLong:
+            case BuiltinType::UInt128:
+                return true;
+            default:
+                break;
+        }
+    }
+    return false;
+}
+
+int getRank(QualType type)
+{
+    auto const t = type->getAs<BuiltinType>();
+    assert(t != nullptr);
+    // Assumes that the only extended signed/unsigned integer types supported by Clang are Int128
+    // and UInt128:
+    switch (t->getKind())
+    {
+        case BuiltinType::SChar:
+        case BuiltinType::UChar:
+            return 0;
+        case BuiltinType::Short:
+        case BuiltinType::UShort:
+            return 1;
+        case BuiltinType::Int:
+        case BuiltinType::UInt:
+            return 2;
+        case BuiltinType::Long:
+        case BuiltinType::ULong:
+            return 3;
+        case BuiltinType::LongLong:
+        case BuiltinType::ULongLong:
+            return 4;
+        case BuiltinType::Int128:
+        case BuiltinType::UInt128:
+            return 5;
+        default:
+            llvm_unreachable("bad integer type");
+    }
+}
+
+int orderTypes(QualType type1, QualType type2)
+{
+    auto const r1 = getRank(type1);
+    auto const r2 = getRank(type2);
+    return r1 < r2 ? -1 : r1 == r2 ? 0 : 1;
+}
+
+class UnsignedCompare : public loplugin::FilteringPlugin<UnsignedCompare>
+{
+public:
+    explicit UnsignedCompare(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    bool VisitBinaryOperator(BinaryOperator const* expr)
+    {
+        if (ignoreLocation(expr))
+        {
+            return true;
+        }
+        // o3tl::make_unsigned requires its argument to be non-negative, but this plugin doesn't
+        // check that when it reports its finding, so will produce false positives when the cast is
+        // actually meant to e.g. clamp from a large signed type to a small unsigned type.  The
+        // assumption is that this will only be likely the case for BO_EQ (==) and BO_NE (!=)
+        // comparisons, so filter these out here (not sure what case BO_Cmp (<=>) will turn out to
+        // be, so lets keep it here at least for now):
+        switch (expr->getOpcode())
+        {
+            case BO_Cmp:
+            case BO_LT:
+            case BO_GT:
+            case BO_LE:
+            case BO_GE:
+                break;
+            default:
+                return true;
+        }
+        auto const castL = isCastToUnsigned(expr->getLHS());
+        auto const castR = isCastToUnsigned(expr->getRHS());
+        //TODO(?): Also report somewhat suspicious cases where both sides are cast to unsigned:
+        if ((castL == nullptr) == (castR == nullptr))
+        {
+            return true;
+        }
+        auto const cast = castL != nullptr ? castL : castR;
+        auto const other = castL != nullptr ? expr->getRHS() : expr->getLHS();
+        auto const otherT = other->IgnoreImpCasts()->getType();
+        if (!isUnsignedIntegerType(otherT))
+        {
+            return true;
+        }
+        auto const castFromT = cast->getSubExprAsWritten()->getType();
+        auto const castToT = cast->getTypeAsWritten();
+        report(DiagnosticsEngine::Warning,
+               "explicit cast from %0 to %1 (of %select{smaller|equal|larger}2 rank) in comparison "
+               "against %3: if the cast value is known to be non-negative, use o3tl::make_unsigned "
+               "instead of the cast",
+               cast->getExprLoc())
+            << castFromT << castToT << (orderTypes(castToT, castFromT) + 1) << otherT
+            << expr->getSourceRange();
+        return true;
+    }
+
+    bool preRun() override
+    {
+        return compiler.getLangOpts().CPlusPlus
+               && compiler.getPreprocessor()
+                      .getIdentifierInfo("LIBO_INTERNAL_ONLY")
+                      ->hasMacroDefinition();
+    }
+
+    void run() override
+    {
+        if (preRun())
+        {
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+        }
+    }
+
+private:
+    ExplicitCastExpr const* isCastToUnsigned(Expr const* expr)
+    {
+        auto const e = dyn_cast<ExplicitCastExpr>(expr->IgnoreParenImpCasts());
+        if (e == nullptr)
+        {
+            return nullptr;
+        }
+        auto const t1 = e->getTypeAsWritten();
+        if (!isUnsignedIntegerType(t1))
+        {
+            return nullptr;
+        }
+        auto const e2 = e->getSubExprAsWritten();
+        auto const t2 = e2->getType();
+        if (!isSignedIntegerType(t2))
+        {
+            return nullptr;
+        }
+        // Filter out e.g. `size_t(-1)`:
+        if (!e2->isValueDependent())
+        {
+            if (auto const val = e2->getIntegerConstantExpr(compiler.getASTContext()))
+            {
+                if (val->isNegative())
+                {
+                    return nullptr;
+                }
+            }
+        }
+        auto loc = e->getBeginLoc();
+        while (compiler.getSourceManager().isMacroArgExpansion(loc))
+        {
+            loc = compiler.getSourceManager().getImmediateMacroCallerLoc(loc);
+        }
+        // This covers both "plain" code in such include files, as well as expansion of (object-like) macros like
+        //
+        //   #define SAL_MAX_INT8          ((sal_Int8)   0x7F)
+        //
+        // defined in such include files:
+        if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(loc)))
+        { //TODO: '#ifdef LIBO_INTERNAL_ONLY' within UNO include files
+            return nullptr;
+        }
+        return e;
+    }
+};
+
+loplugin::Plugin::Registration<UnsignedCompare> unsignedcompare("unsignedcompare");
+}
+
+#endif // LO_CLANG_SHARED_PLUGINS
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */