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-rw-r--r--compilerplugins/clang/store/defaultparams.cxx128
1 files changed, 128 insertions, 0 deletions
diff --git a/compilerplugins/clang/store/defaultparams.cxx b/compilerplugins/clang/store/defaultparams.cxx
new file mode 100644
index 000000000..cb533cb19
--- /dev/null
+++ b/compilerplugins/clang/store/defaultparams.cxx
@@ -0,0 +1,128 @@
+/* -*- 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/.
+ */
+
+#include <string>
+#include <set>
+
+#include "plugin.hxx"
+
+// Find places where we call a method with values == the values specified in the parameter defaults.
+// i.e. where the code might as well not specify anything.
+
+namespace {
+
+class DefaultParams:
+ public loplugin::FilteringPlugin<DefaultParams>
+{
+public:
+ explicit DefaultParams(InstantiationData const & data): FilteringPlugin(data) {}
+
+ virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+ bool VisitCallExpr(CallExpr * callExpr);
+private:
+ bool evaluate(const Expr* expr, APSInt& x);
+};
+
+bool DefaultParams::VisitCallExpr(CallExpr * callExpr) {
+ if (ignoreLocation(callExpr)) {
+ return true;
+ }
+ if (callExpr->getDirectCallee() == nullptr) {
+ return true;
+ }
+ const FunctionDecl* functionDecl = callExpr->getDirectCallee()->getCanonicalDecl();
+ auto n = functionDecl->getNumParams();
+ if (n == 0 || !functionDecl->getParamDecl(n - 1)->hasDefaultArg()) {
+ return true;
+ }
+ assert(callExpr->getNumArgs() <= n); // can be < in template code
+ for (unsigned i = callExpr->getNumArgs(); i != 0;) {
+ --i;
+ Expr* arg = callExpr->getArg(i);
+ if (arg->isDefaultArgument()) {
+ continue;
+ }
+ // ignore this, it seems to trigger an infinite recursion
+ if (isa<UnaryExprOrTypeTraitExpr>(arg))
+ break;
+ const ParmVarDecl* parmVarDecl = functionDecl->getParamDecl(i);
+ if (!parmVarDecl->hasDefaultArg()
+ || parmVarDecl->hasUninstantiatedDefaultArg())
+ {
+ break;
+ }
+ const Expr* defaultArgExpr = parmVarDecl->getDefaultArg();
+ if (!defaultArgExpr) {
+ break;
+ }
+ bool found = false;
+ if (defaultArgExpr->isNullPointerConstant(compiler.getASTContext(), Expr::NPC_NeverValueDependent)
+ && arg->isNullPointerConstant(compiler.getASTContext(), Expr::NPC_NeverValueDependent))
+ {
+ found = true;
+ }
+ if (!found)
+ {
+ APSInt x1, x2;
+ if (evaluate(defaultArgExpr, x1) && evaluate(arg, x2) && x1 == x2)
+ {
+ found = true;
+ }
+ }
+ // catch params with defaults like "= OUString()"
+ if (!found
+ && isa<MaterializeTemporaryExpr>(arg)
+ && isa<MaterializeTemporaryExpr>(defaultArgExpr))
+ {
+ const CXXBindTemporaryExpr* strippedArg = dyn_cast_or_null<CXXBindTemporaryExpr>(arg->IgnoreParenCasts());
+ if (strippedArg && isa<CXXTemporaryObjectExpr>(strippedArg->getSubExpr())
+ && dyn_cast<CXXTemporaryObjectExpr>(strippedArg->getSubExpr())->getNumArgs() == 0)
+ {
+ found = true;
+ }
+ }
+ if (!found)
+ break;
+ // Ignore CPPUNIT, it's macros contain some stuff that triggers us
+ StringRef aFileName = getFilenameOfLocation(compiler.getSourceManager().getSpellingLoc(parmVarDecl->getLocStart()));
+ if (aFileName.find("include/cppunit") != std::string::npos)
+ break;
+ report(
+ DiagnosticsEngine::Warning,
+ "not necessary to pass this argument, it defaults to the same value",
+ arg->getSourceRange().getBegin())
+ << arg->getSourceRange();
+ report(
+ DiagnosticsEngine::Note,
+ "default method parameter declaration here",
+ parmVarDecl->getSourceRange().getBegin())
+ << parmVarDecl->getSourceRange();
+ }
+ return true;
+}
+
+bool DefaultParams::evaluate(const Expr* expr, APSInt& x)
+{
+ if (isa<CXXNullPtrLiteralExpr>(expr)) {
+ x = 0;
+ return true;
+ }
+ if (expr->EvaluateAsInt(x, compiler.getASTContext()))
+ {
+ return true;
+ }
+ return false;
+}
+
+loplugin::Plugin::Registration< DefaultParams > X("defaultparams");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */