//===--- AssertSideEffectCheck.cpp - clang-tidy ---------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "AssertSideEffectCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/Lexer.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include <algorithm>
#include <string>

using namespace clang::ast_matchers;

namespace clang {
namespace {

AST_MATCHER_P(Expr, hasSideEffect, bool, CheckFunctionCalls) {
  const Expr *E = &Node;

  if (const auto *Op = dyn_cast<UnaryOperator>(E)) {
    UnaryOperator::Opcode OC = Op->getOpcode();
    return OC == UO_PostInc || OC == UO_PostDec || OC == UO_PreInc ||
           OC == UO_PreDec;
  }

  if (const auto *Op = dyn_cast<BinaryOperator>(E)) {
    BinaryOperator::Opcode OC = Op->getOpcode();
    return OC == BO_Assign || OC == BO_MulAssign || OC == BO_DivAssign ||
           OC == BO_RemAssign || OC == BO_AddAssign || OC == BO_SubAssign ||
           OC == BO_ShlAssign || OC == BO_ShrAssign || OC == BO_AndAssign ||
           OC == BO_XorAssign || OC == BO_OrAssign;
  }

  if (const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
    OverloadedOperatorKind OpKind = OpCallExpr->getOperator();
    return OpKind == OO_Equal || OpKind == OO_PlusEqual ||
           OpKind == OO_MinusEqual || OpKind == OO_StarEqual ||
           OpKind == OO_SlashEqual || OpKind == OO_AmpEqual ||
           OpKind == OO_PipeEqual || OpKind == OO_CaretEqual ||
           OpKind == OO_LessLessEqual || OpKind == OO_GreaterGreaterEqual ||
           OpKind == OO_PlusPlus || OpKind == OO_MinusMinus ||
           OpKind == OO_PercentEqual || OpKind == OO_New ||
           OpKind == OO_Delete || OpKind == OO_Array_New ||
           OpKind == OO_Array_Delete;
  }

  if (const auto *CExpr = dyn_cast<CallExpr>(E)) {
    bool Result = CheckFunctionCalls;
    if (const auto *FuncDecl = CExpr->getDirectCallee()) {
      if (FuncDecl->getDeclName().isIdentifier() &&
          FuncDecl->getName() == "__builtin_expect") // exceptions come here
        Result = false;
      else if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
        Result &= !MethodDecl->isConst();
    }
    return Result;
  }

  return isa<CXXNewExpr>(E) || isa<CXXDeleteExpr>(E) || isa<CXXThrowExpr>(E);
}

} // namespace

namespace tidy {

AssertSideEffectCheck::AssertSideEffectCheck(StringRef Name,
                                             ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      CheckFunctionCalls(Options.get("CheckFunctionCalls", false)),
      RawAssertList(Options.get("AssertMacros", "assert")) {
  StringRef(RawAssertList).split(AssertMacros, ",", -1, false);
}

// The options are explained in AssertSideEffectCheck.h.
void AssertSideEffectCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "CheckFunctionCalls", CheckFunctionCalls);
  Options.store(Opts, "AssertMacros", RawAssertList);
}

void AssertSideEffectCheck::registerMatchers(MatchFinder *Finder) {
  auto ConditionWithSideEffect =
      hasCondition(hasDescendant(expr(hasSideEffect(CheckFunctionCalls))));
  Finder->addMatcher(
      stmt(anyOf(conditionalOperator(ConditionWithSideEffect),
                 ifStmt(ConditionWithSideEffect))).bind("condStmt"),
      this);
}

void AssertSideEffectCheck::check(const MatchFinder::MatchResult &Result) {
  const ASTContext *ASTCtx = Result.Context;
  const auto *CondStmt = Result.Nodes.getNodeAs<Stmt>("condStmt");
  SourceLocation Loc = CondStmt->getLocStart();

  if (!Loc.isValid() || !Loc.isMacroID())
    return;

  StringRef MacroName = Lexer::getImmediateMacroName(
      Loc, ASTCtx->getSourceManager(), ASTCtx->getLangOpts());

  // Check if this macro is an assert.
  if (std::find(AssertMacros.begin(), AssertMacros.end(), MacroName) ==
      AssertMacros.end())
    return;

  diag(Loc, "found " + MacroName.str() + "() with side effect");
}

} // namespace tidy
} // namespace clang