New loplugin:conditionalstring

Change-Id: I2eab990c15f845b44a3b598571aca361dadf9ff3
Reviewed-on: https://gerrit.libreoffice.org/81946
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 492 insertions, 0 deletions

diff --git a/compilerplugins/clang/conditionalstring.cxx b/compilerplugins/clang/conditionalstring.cxx
new file mode 100644
index 000000000000..d09472c25446
--- /dev/null
+++ b/compilerplugins/clang/conditionalstring.cxx
@@ -0,0 +1,462 @@
+/* -*- 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
+
+#include <cassert>
+
+#include "check.hxx"
+#include "compat.hxx"
+#include "plugin.hxx"
+
+// Find uses of OUString in conditional expressions that could be rewritten as OUStringLiteral, as
+// in
+//
+//   s += (b ? OUString("xy") : OUString(z");
+
+namespace
+{
+// Like Expr::IgnoreImplicit, but for an ImplicitCastExpr skips to getSubExprAsWritten (so skips a
+// CXXConstructExpr where Expr::IgnoreImplicit would stop):
+Expr const* ignoreImplicit(Expr const* expr)
+{
+    for (auto e = expr;;)
+    {
+        if (auto const e1 = dyn_cast<ImplicitCastExpr>(e))
+        {
+            e = e1->getSubExprAsWritten();
+        }
+#if CLANG_VERSION >= 80000
+        else if (auto const e2 = dyn_cast<FullExpr>(e))
+        {
+            e = e2->getSubExpr();
+        }
+#endif
+        else if (auto const e3 = dyn_cast<MaterializeTemporaryExpr>(e))
+        {
+            e = e3->GetTemporaryExpr();
+        }
+        else if (auto const e4 = dyn_cast<CXXBindTemporaryExpr>(e))
+        {
+            e = e4->getSubExpr();
+        }
+        else
+        {
+            return e;
+        }
+    }
+}
+
+class ConditionalString final : public loplugin::FilteringPlugin<ConditionalString>
+{
+public:
+    explicit ConditionalString(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    bool VisitCallExpr(CallExpr const* expr)
+    {
+        if (ignoreLocation(expr))
+        {
+            return true;
+        }
+        auto const fn = expr->getDirectCallee();
+        if (fn == nullptr)
+        {
+            return true;
+        }
+        //TODO: Instead of a hardcoded list of functions, check that `fn` has overloads taking
+        // OUString and OUStringLiteral, respectively (and operator + is even more complicated than
+        // that, going via ToStringHelper<OUStringLiteral> specialization; the getNumArgs checks for
+        // the various functions are meant to guard against the unlikely case that the affected
+        // parameters get defaulted in the future; overloaded operators cannot generally have
+        // defaulted parameters):
+        loplugin::DeclCheck const dc(fn);
+        if (dc.Operator(OO_Equal).Class("OUString").Namespace("rtl").GlobalNamespace())
+        {
+            assert(fn->getNumParams() == 1);
+            if (isa<CXXOperatorCallExpr>(expr))
+            {
+                assert(expr->getNumArgs() == 2);
+                check(expr->getArg(1));
+            }
+            else
+            {
+                assert(expr->getNumArgs() == 1);
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Operator(OO_PlusEqual).Class("OUString").Namespace("rtl").GlobalNamespace())
+        {
+            assert(fn->getNumParams() == 1);
+            if (isa<CXXOperatorCallExpr>(expr))
+            {
+                assert(expr->getNumArgs() == 2);
+                check(expr->getArg(1));
+            }
+            else
+            {
+                assert(expr->getNumArgs() == 1);
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("reverseCompareTo").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 1)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("equalsIgnoreAsciiCase")
+                .Class("OUString")
+                .Namespace("rtl")
+                .GlobalNamespace()
+            && fn->getNumParams() == 1)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("match").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("matchIgnoreAsciiCase").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("startsWith").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("startsWithIgnoreAsciiCase")
+                .Class("OUString")
+                .Namespace("rtl")
+                .GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("endsWith").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("endsWithIgnoreAsciiCase")
+                .Class("OUString")
+                .Namespace("rtl")
+                .GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Operator(OO_EqualEqual)
+                .Namespace("rtl")
+                .GlobalNamespace()) //TODO: more precicse check
+        {
+            assert(fn->getNumParams() == 2);
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Operator(OO_ExclaimEqual)
+                .Namespace("rtl")
+                .GlobalNamespace()) //TODO: more precicse check
+        {
+            assert(fn->getNumParams() == 2);
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Operator(OO_Less).Namespace("rtl").GlobalNamespace()) //TODO: more precicse check
+        {
+            assert(fn->getNumParams() == 2);
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Operator(OO_LessEqual)
+                .Namespace("rtl")
+                .GlobalNamespace()) //TODO: more precicse check
+        {
+            assert(fn->getNumParams() == 2);
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Operator(OO_Greater).Namespace("rtl").GlobalNamespace()) //TODO: more precicse check
+        {
+            assert(fn->getNumParams() == 2);
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Operator(OO_GreaterEqual)
+                .Namespace("rtl")
+                .GlobalNamespace()) //TODO: more precicse check
+        {
+            assert(fn->getNumParams() == 2);
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Function("indexOf").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("lastIndexOf").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 1)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("replaceFirst").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 3)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            if (expr->getNumArgs() >= 2)
+            {
+                check(expr->getArg(1));
+            }
+            return true;
+        }
+        if (dc.Function("replaceAll").Class("OUString").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            if (expr->getNumArgs() >= 2)
+            {
+                check(expr->getArg(1));
+            }
+            return true;
+        }
+        if (dc.Operator(OO_Plus).Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2) //TODO: more precicse check
+        {
+            assert(expr->getNumArgs() == 2);
+            check(expr->getArg(0));
+            check(expr->getArg(1));
+            return true;
+        }
+        if (dc.Operator(OO_Equal).Class("OUStringBuffer").Namespace("rtl").GlobalNamespace())
+        {
+            assert(fn->getNumParams() == 1);
+            if (isa<CXXOperatorCallExpr>(expr))
+            {
+                assert(expr->getNumArgs() == 2);
+                check(expr->getArg(1));
+            }
+            else
+            {
+                assert(expr->getNumArgs() == 1);
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("append").Class("OUStringBuffer").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 1)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("insert").Class("OUStringBuffer").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 2)
+            {
+                check(expr->getArg(1));
+            }
+            return true;
+        }
+        if (dc.Function("indexOf").Class("OUStringBuffer").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 2)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        if (dc.Function("lastIndexOf").Class("OUStringBuffer").Namespace("rtl").GlobalNamespace()
+            && fn->getNumParams() == 1)
+        {
+            if (expr->getNumArgs() >= 1)
+            {
+                check(expr->getArg(0));
+            }
+            return true;
+        }
+        return true;
+    }
+
+    bool preRun() override { return compiler.getLangOpts().CPlusPlus; }
+
+private:
+    enum class Kind
+    {
+        OUStringFromLiteral,
+        OUStringLiteralOrVoid,
+        Other
+    };
+
+    void run() override
+    {
+        if (preRun())
+        {
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+        }
+    }
+
+    Kind getKind(Expr const* expr)
+    {
+        auto const tc = loplugin::TypeCheck(ignoreImplicit(expr)->getType());
+        if (tc.Struct("OUStringLiteral").Namespace("rtl").GlobalNamespace() || tc.Void())
+        {
+            return Kind::OUStringLiteralOrVoid;
+        }
+        if (loplugin::TypeCheck(expr->getType())
+                .Class("OUString")
+                .Namespace("rtl")
+                .GlobalNamespace())
+        {
+            // Check for both explicit
+            //
+            //   OUString("...")
+            //
+            // and implicit
+            //
+            //    "..."
+            //
+            // expressions:
+            auto e = expr->IgnoreParens();
+            if (auto const e1 = dyn_cast<CXXFunctionalCastExpr>(e))
+            {
+                e = e1->getSubExpr();
+            }
+            if (auto const e1
+                = dyn_cast<CXXConstructExpr>(compat::IgnoreImplicit(e)->IgnoreParens()))
+            {
+                if (e1->getNumArgs() != 0 //TODO
+                    && isa<clang::StringLiteral>(e1->getArg(0)->IgnoreParenImpCasts()))
+                {
+                    return Kind::OUStringFromLiteral;
+                }
+            }
+        }
+        return Kind::Other;
+    }
+
+    void check(Expr const* expr)
+    {
+        //TODO: skip `,`; handle ?: chains
+        auto const cond = dyn_cast<ConditionalOperator>(expr->IgnoreParenImpCasts());
+        if (cond == nullptr)
+        {
+            return;
+        }
+        auto const k1 = getKind(cond->getTrueExpr());
+        if (k1 == Kind::Other)
+        {
+            return;
+        }
+        auto const k2 = getKind(cond->getFalseExpr());
+        if (k2 == Kind::Other
+            || (k1 == Kind::OUStringLiteralOrVoid && k2 == Kind::OUStringLiteralOrVoid))
+        {
+            return;
+        }
+        if (k1 == Kind::OUStringFromLiteral && k2 == Kind::OUStringFromLiteral)
+        {
+            report(DiagnosticsEngine::Warning,
+                   ("replace both 2nd and 3rd operands of conditional expression with"
+                    " `rtl::OUStringLiteral`"),
+                   cond->getExprLoc())
+                << cond->getSourceRange();
+        }
+        else
+        {
+            assert((k1 == Kind::OUStringFromLiteral && k2 == Kind::OUStringLiteralOrVoid)
+                   || (k1 == Kind::OUStringLiteralOrVoid && k2 == Kind::OUStringFromLiteral));
+            auto const second = k1 == Kind::OUStringFromLiteral;
+            auto const sub
+                = (second ? cond->getTrueExpr() : cond->getFalseExpr())->IgnoreParenImpCasts();
+            report(DiagnosticsEngine::Warning,
+                   ("replace %select{2nd|3rd}0 operand of conditional expression with"
+                    " `rtl::OUStringLiteral`"),
+                   sub->getExprLoc())
+                << (second ? 0 : 1) << sub->getSourceRange();
+            report(DiagnosticsEngine::Note, "conditional expression is here", cond->getExprLoc())
+                << cond->getSourceRange();
+        }
+    }
+};
+
+loplugin::Plugin::Registration<ConditionalString> conditionalstring("conditionalstring");
+}
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/test/conditionalstring.cxx b/compilerplugins/clang/test/conditionalstring.cxx
new file mode 100644
index 000000000000..e10b02519f8e
--- /dev/null
+++ b/compilerplugins/clang/test/conditionalstring.cxx
@@ -0,0 +1,30 @@
+/* -*- 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/.
+ */
+
+#include <sal/config.h>
+
+#include <rtl/ustring.hxx>
+
+void f(OUString s, bool b)
+{
+    // expected-error@+2 {{replace 2nd operand of conditional expression with `rtl::OUStringLiteral` [loplugin:conditionalstring]}}
+    // expected-note@+1 {{conditional expression is here [loplugin:conditionalstring]}}
+    s += (b ? OUString("a") : throw 0);
+    // expected-error@+2 {{replace 2nd operand of conditional expression with `rtl::OUStringLiteral` [loplugin:conditionalstring]}}
+    // expected-note@+1 {{conditional expression is here [loplugin:conditionalstring]}}
+    s += (b ? OUString("a") : OUStringLiteral("b"));
+    // expected-error@+1 {{replace both 2nd and 3rd operands of conditional expression with `rtl::OUStringLiteral` [loplugin:conditionalstring]}}
+    b = (b ? ("x") : (OUString(("y")))) == s;
+    // expected-error@+1 {{replace both 2nd and 3rd operands of conditional expression with `rtl::OUStringLiteral` [loplugin:conditionalstring]}}
+    b = operator==(s, b ? OUString("x") : OUString("y"));
+    // expected-error@+1 {{replace both 2nd and 3rd operands of conditional expression with `rtl::OUStringLiteral` [loplugin:conditionalstring]}}
+    s.operator+=(b ? OUString("x") : OUString("y"));
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */