Enable loplugin:nullptr

I had it locally enabled for like a month now, and it did not produce any more
noise than any of the other plugins.

Change-Id: I94dab702c537969cf32922f6e88b4f5b503cd3f5

1 files changed, 323 insertions, 0 deletions

diff --git a/compilerplugins/clang/nullptr.cxx b/compilerplugins/clang/nullptr.cxx
new file mode 100644
index 000000000000..6bf4e54d3f15
--- /dev/null
+++ b/compilerplugins/clang/nullptr.cxx
@@ -0,0 +1,323 @@
+/* -*- 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 <cassert>
+#include <set>
+
+#include "compat.hxx"
+#include "plugin.hxx"
+
+namespace {
+
+char const * kindName(Expr::NullPointerConstantKind kind) {
+    switch (kind) {
+    case Expr::NPCK_NotNull:
+        assert(false); // cannot happen
+        // fall through
+    case Expr::NPCK_ZeroExpression:
+        return "ZeroExpression";
+    case Expr::NPCK_ZeroLiteral:
+        return "ZeroLiteral";
+    case Expr::NPCK_CXX11_nullptr:
+        return "CXX11_nullptr";
+    case Expr::NPCK_GNUNull:
+        return "GNUNull";
+    }
+}
+
+class Nullptr:
+    public RecursiveASTVisitor<Nullptr>, public loplugin::RewritePlugin
+{
+public:
+    explicit Nullptr(InstantiationData const & data): RewritePlugin(data) {}
+
+    void run() override
+    { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitImplicitCastExpr(CastExpr const * expr);
+
+    bool VisitGNUNullExpr(GNUNullExpr const * expr);
+
+    bool VisitBinaryOperator(BinaryOperator const * expr);
+
+    bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr const * expr);
+
+    // bool shouldVisitTemplateInstantiations() const { return true; }
+
+private:
+    bool isInLokIncludeFile(SourceLocation spellingLocation) const;
+
+    bool isFromCIncludeFile(SourceLocation spellingLocation) const;
+
+    bool isMacroBodyExpansion(SourceLocation location) const;
+
+    void handleNull(
+        Expr const * expr, char const * castKind,
+        Expr::NullPointerConstantKind nullPointerKind);
+
+    void rewriteOrWarn(
+        Expr const * expr, char const * castKind,
+        Expr::NullPointerConstantKind nullPointerKind,
+        char const * replacement);
+
+    std::set<Expr const *> gnuNulls_;
+};
+
+bool Nullptr::VisitImplicitCastExpr(CastExpr const * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    switch (expr->getCastKind()) {
+    case CK_NullToPointer:
+    case CK_NullToMemberPointer:
+        break;
+    default:
+        return true;
+    }
+    Expr::NullPointerConstantKind k = expr->isNullPointerConstant(
+        compiler.getASTContext(), Expr::NPC_ValueDependentIsNotNull);
+    switch (k) {
+    case Expr::NPCK_NotNull:
+        k = expr->isNullPointerConstant(
+            compiler.getASTContext(), Expr::NPC_ValueDependentIsNull);
+        switch (k) {
+        case Expr::NPCK_NotNull:
+            break;
+        case Expr::NPCK_ZeroExpression:
+        case Expr::NPCK_ZeroLiteral:
+            report(
+                DiagnosticsEngine::Warning,
+                "suspicious ValueDependentIsNull %0", expr->getLocStart())
+                << kindName(k) << expr->getSourceRange();
+            break;
+        default:
+            assert(false); // cannot happen
+        }
+        break;
+    case Expr::NPCK_CXX11_nullptr:
+        break;
+    default:
+        handleNull(expr->getSubExpr(), expr->getCastKindName(), k);
+        break;
+    }
+    return true;
+}
+
+bool Nullptr::VisitGNUNullExpr(GNUNullExpr const * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    handleNull(expr, nullptr, Expr::NPCK_GNUNull);
+    return true;
+}
+
+bool Nullptr::VisitBinaryOperator(BinaryOperator const * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    Expr const * e;
+    switch (expr->getOpcode()) {
+    case BO_EQ:
+    case BO_NE:
+        if (expr->getRHS()->getType()->isPointerType()) {
+            e = expr->getLHS();
+            break;
+        }
+        // fall through
+    case BO_Assign:
+        if (expr->getLHS()->getType()->isPointerType()) {
+            e = expr->getRHS();
+            break;
+        }
+        // fall through
+    default:
+        return true;
+    }
+    //TODO: detect NPCK_ZeroExpression where appropriate
+    auto const lit = dyn_cast<IntegerLiteral>(e->IgnoreParenImpCasts());
+    if (lit == nullptr || lit->getValue().getBoolValue()) {
+        return true;
+    }
+    handleNull(e, nullptr, Expr::NPCK_ZeroLiteral);
+    return true;
+}
+
+bool Nullptr::VisitCXXOperatorCallExpr(CXXOperatorCallExpr const * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    Expr const * e;
+    switch (expr->getOperator()) {
+    case OO_EqualEqual:
+    case OO_ExclaimEqual:
+        if (expr->getArg(1)->getType()->isPointerType()) {
+            e = expr->getArg(0);
+            break;
+        }
+        // fall through
+    case OO_Equal:
+        if (expr->getArg(0)->getType()->isPointerType()) {
+            e = expr->getArg(1);
+            break;
+        }
+        // fall through
+    default:
+        return true;
+    }
+    //TODO: detect NPCK_ZeroExpression where appropriate
+    auto const lit = dyn_cast<IntegerLiteral>(e->IgnoreParenImpCasts());
+    if (lit == nullptr || lit->getValue().getBoolValue()) {
+        return true;
+    }
+    handleNull(e, nullptr, Expr::NPCK_ZeroLiteral);
+    return true;
+}
+
+bool Nullptr::isInLokIncludeFile(SourceLocation spellingLocation) const {
+    return compiler.getSourceManager().getFilename(spellingLocation)
+        .startswith(SRCDIR "/include/LibreOfficeKit/");
+}
+
+bool Nullptr::isFromCIncludeFile(SourceLocation spellingLocation) const {
+    return !compat::isInMainFile(compiler.getSourceManager(), spellingLocation)
+        && (StringRef(
+                compiler.getSourceManager().getPresumedLoc(spellingLocation)
+                .getFilename())
+            .endswith(".h"));
+}
+
+bool Nullptr::isMacroBodyExpansion(SourceLocation location) const {
+#if (__clang_major__ == 3 && __clang_minor__ >= 3) || __clang_major__ > 3
+    return compiler.getSourceManager().isMacroBodyExpansion(location);
+#else
+    return location.isMacroID()
+        && !compiler.getSourceManager().isMacroArgExpansion(location);
+#endif
+}
+
+void Nullptr::handleNull(
+    Expr const * expr, char const * castKind,
+    Expr::NullPointerConstantKind nullPointerKind)
+{
+    auto e = expr;
+    SourceLocation loc;
+    for (;;) {
+        e = e->IgnoreImpCasts();
+        loc = e->getLocStart();
+        while (compiler.getSourceManager().isMacroArgExpansion(loc)) {
+            loc = compiler.getSourceManager().getImmediateMacroCallerLoc(loc);
+        }
+        if (isMacroBodyExpansion(loc)) {
+            if (Lexer::getImmediateMacroName(
+                    loc, compiler.getSourceManager(), compiler.getLangOpts())
+                == "NULL")
+            {
+                if (!compiler.getLangOpts().CPlusPlus) {
+                    //TODO: if !castKind, warn if NULL is passed into fn call
+                    // ellipsis, cast to void*
+                    return;
+                }
+                loc = compiler.getSourceManager()
+                    .getImmediateExpansionRange(loc).first;
+                if (isInUnoIncludeFile(
+                        compiler.getSourceManager().getSpellingLoc(loc))
+                    || isInLokIncludeFile(
+                        compiler.getSourceManager().getSpellingLoc(loc))
+                    || isFromCIncludeFile(
+                        compiler.getSourceManager().getSpellingLoc(loc)))
+                {
+                    //TODO: if !castKind, warn if NULL is passed into fn call
+                    // ellipsis, cast to void*
+                    return;
+                }
+            } else if (ignoreLocation(
+                           compiler.getSourceManager().getSpellingLoc(loc)))
+            {
+                return;
+            }
+        }
+        ParenExpr const * pe = dyn_cast<ParenExpr>(e);
+        if (pe == nullptr) {
+            break;
+        }
+        e = pe->getSubExpr();
+    }
+    if (nullPointerKind == Expr::NPCK_GNUNull) {
+        if (castKind == nullptr) {
+            if (gnuNulls_.erase(expr) == 1) {
+                return;
+            }
+        } else {
+            auto const ok = gnuNulls_.insert(expr).second;
+            assert(ok); (void) ok;
+        }
+    }
+    auto const asMacro = !compiler.getLangOpts().CPlusPlus
+        || isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(loc))
+        || isInLokIncludeFile(compiler.getSourceManager().getSpellingLoc(loc))
+        || isFromCIncludeFile(compiler.getSourceManager().getSpellingLoc(loc));
+    assert(!asMacro || nullPointerKind != Expr::NPCK_GNUNull);
+    rewriteOrWarn(e, castKind, nullPointerKind, asMacro ? "NULL" : "nullptr");
+}
+
+void Nullptr::rewriteOrWarn(
+    Expr const * expr, char const * castKind,
+    Expr::NullPointerConstantKind nullPointerKind, char const * replacement)
+{
+    if (rewriter != nullptr) {
+        SourceLocation locStart(expr->getLocStart());
+        while (compiler.getSourceManager().isMacroArgExpansion(locStart)) {
+            locStart = compiler.getSourceManager()
+                .getImmediateMacroCallerLoc(locStart);
+        }
+        if (compiler.getLangOpts().CPlusPlus && isMacroBodyExpansion(locStart)
+            && (Lexer::getImmediateMacroName(
+                    locStart, compiler.getSourceManager(),
+                    compiler.getLangOpts())
+                == "NULL"))
+        {
+            locStart = compiler.getSourceManager().getImmediateExpansionRange(
+                locStart).first;
+        }
+        SourceLocation locEnd(expr->getLocEnd());
+        while (compiler.getSourceManager().isMacroArgExpansion(locEnd)) {
+            locEnd = compiler.getSourceManager()
+                .getImmediateMacroCallerLoc(locEnd);
+        }
+        if (compiler.getLangOpts().CPlusPlus && isMacroBodyExpansion(locEnd)
+            && (Lexer::getImmediateMacroName(
+                    locEnd, compiler.getSourceManager(),
+                    compiler.getLangOpts())
+                == "NULL"))
+        {
+            locEnd = compiler.getSourceManager().getImmediateExpansionRange(
+                locEnd).first;
+        }
+        if (replaceText(SourceRange(compiler.getSourceManager().getSpellingLoc(locStart), compiler.getSourceManager().getSpellingLoc(locEnd)), replacement)) {
+            return;
+        }
+    }
+    if (castKind == nullptr) {
+        report(DiagnosticsEngine::Warning, "%0 -> %1", expr->getLocStart())
+            << kindName(nullPointerKind) << replacement
+            << expr->getSourceRange();
+    } else {
+        report(
+            DiagnosticsEngine::Warning, "%0 ValueDependentIsNotNull %1 -> %2",
+            expr->getLocStart())
+            << castKind << kindName(nullPointerKind) << replacement
+            << expr->getSourceRange();
+    }
+}
+
+loplugin::Plugin::Registration<Nullptr> X("nullptr", true);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */