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-rw-r--r--compilerplugins/clang/intvsfloat.cxx117
1 files changed, 117 insertions, 0 deletions
diff --git a/compilerplugins/clang/intvsfloat.cxx b/compilerplugins/clang/intvsfloat.cxx
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+++ b/compilerplugins/clang/intvsfloat.cxx
@@ -0,0 +1,117 @@
+/* -*- 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/.
+ */
+#ifndef LO_CLANG_SHARED_PLUGINS
+
+#include "plugin.hxx"
+#include "check.hxx"
+#include "compat.hxx"
+#include <iostream>
+
+/**
+
+TODO multiplying/otherop on a combination of a float and int, and then truncating to int. like this:
+ float getRotation() {}
+ int moRotation = -F_PI180 * 90 * getRotation();
+*/
+namespace
+{
+class IntVsFloat : public loplugin::FilteringPlugin<IntVsFloat>
+{
+public:
+ explicit IntVsFloat(loplugin::InstantiationData const& data)
+ : loplugin::FilteringPlugin<IntVsFloat>(data)
+ {
+ }
+
+ void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+ bool VisitVarDecl(VarDecl const*);
+ bool VisitBinaryOperator(BinaryOperator const*);
+
+private:
+ compat::optional<double> getExprValue(Expr const* expr);
+};
+
+bool IntVsFloat::VisitVarDecl(VarDecl const* varDecl)
+{
+ if (ignoreLocation(varDecl->getLocation()))
+ return true;
+ auto init = varDecl->getInit();
+ if (!init)
+ return true;
+ init = init->IgnoreImpCasts();
+ if (varDecl->getType()->isFloatingType())
+ return true;
+ // init->dump();
+ compat::optional<double> d = getExprValue(init);
+ if (!d)
+ return true;
+ if (static_cast<long>(*d) == *d)
+ return true;
+ report(DiagnosticsEngine::Warning, "assigning constant float value to int truncates data",
+ init->getBeginLoc())
+ << init->getSourceRange();
+
+ return true;
+}
+
+bool IntVsFloat::VisitBinaryOperator(BinaryOperator const* op)
+{
+ if (op->getOpcode() != BO_EQ)
+ {
+ return true;
+ }
+ if (ignoreLocation(op->getBeginLoc()))
+ return true;
+ auto lhs = op->getLHS()->IgnoreImpCasts();
+ auto rhs = op->getRHS()->IgnoreImpCasts();
+ if (!lhs->getType()->isFloatingType())
+ std::swap(lhs, rhs);
+ if (!lhs->getType()->isFloatingType())
+ return true;
+ if (rhs->getType()->isFloatingType())
+ return true;
+ compat::optional<double> d = getExprValue(lhs);
+ if (!d)
+ return true;
+ if (static_cast<long>(*d) == *d)
+ return true;
+ report(DiagnosticsEngine::Warning, "comparing integer to float constant, can never be true",
+ op->getBeginLoc())
+ << op->getSourceRange();
+ return true;
+}
+
+compat::optional<double> IntVsFloat::getExprValue(Expr const* expr)
+{
+ // Of the available clang Evaluate* APIs, this is the __only__ one that produces useful output
+ // (as of 17 Aug 2018 checkout of clang, ie. towards clang 7)
+
+ if (expr->isValueDependent())
+ return compat::optional<double>();
+ Expr::EvalResult evalResult;
+ if (!expr->EvaluateAsRValue(evalResult, compiler.getASTContext()))
+ return compat::optional<double>();
+ if (!evalResult.Val.isFloat())
+ return compat::optional<double>();
+ llvm::APFloat floatResult = evalResult.Val.getFloat();
+ bool losesInfo;
+ floatResult.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven, &losesInfo);
+
+ double d = floatResult.convertToDouble();
+ return d;
+}
+
+loplugin::Plugin::Registration<IntVsFloat> intvsfloat("intvsfloat");
+
+} // namespace
+
+#endif // LO_CLANG_SHARED_PLUGINS
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */