//===- CalledOnceCheck.h - Check 'called once' parameters -------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines a check for function-like parameters that should be
// called exactly one time.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_ANALYSIS_ANALYSES_CALLEDONCECHECK_H
#define LLVM_CLANG_ANALYSIS_ANALYSES_CALLEDONCECHECK_H
namespace clang {
class AnalysisDeclContext;
class BlockDecl;
class CFG;
class Decl;
class Expr;
class ParmVarDecl;
class Stmt;
/// Classification of situations when parameter is not called on every path.
/// \enum IfThen -- then branch of the if statement has no call.
/// \enum IfElse -- else branch of the if statement has no call.
/// \enum Switch -- one of the switch cases doesn't have a call.
/// \enum SwitchSkipped -- there is no call if none of the cases appies.
/// \enum LoopEntered -- no call when the loop is entered.
/// \enum LoopSkipped -- no call when the loop is not entered.
/// \enum FallbackReason -- fallback case when we were not able to figure out
/// the reason.
enum class NeverCalledReason {
IfThen,
IfElse,
Switch,
SwitchSkipped,
LoopEntered,
LoopSkipped,
FallbackReason,
LARGEST_VALUE = FallbackReason
};
class CalledOnceCheckHandler {
public:
CalledOnceCheckHandler() = default;
virtual ~CalledOnceCheckHandler() = default;
/// Called when parameter is called twice.
/// \param Parameter -- parameter that should be called once.
/// \param Call -- call to report the warning.
/// \param PrevCall -- previous call.
/// \param IsCompletionHandler -- true, if parameter is a completion handler.
/// \param Poised -- true, if the second call is guaranteed to happen after
/// the first call.
virtual void handleDoubleCall(const ParmVarDecl *Parameter, const Expr *Call,
const Expr *PrevCall, bool IsCompletionHandler,
bool Poised) {}
/// Called when parameter is not called at all.
/// \param Parameter -- parameter that should be called once.
/// \param IsCompletionHandler -- true, if parameter is a completion handler.
virtual void handleNeverCalled(const ParmVarDecl *Parameter,
bool IsCompletionHandler) {}
/// Called when captured parameter is not called at all.
/// \param Parameter -- parameter that should be called once.
/// \param Where -- declaration that captures \p Parameter
/// \param IsCompletionHandler -- true, if parameter is a completion handler.
virtual void handleCapturedNeverCalled(const ParmVarDecl *Parameter,
const Decl *Where,
bool IsCompletionHandler) {}
/// Called when parameter is not called on one of the paths.
/// Usually we try to find a statement that is the least common ancestor of
/// the path containing the call and not containing the call. This helps us
/// to pinpoint a bad path for the user.
/// \param Parameter -- parameter that should be called once.
/// \param Function -- function declaration where the problem occurred.
/// \param Where -- the least common ancestor statement.
/// \param Reason -- a reason describing the path without a call.
/// \param IsCalledDirectly -- true, if parameter actually gets called on
/// the other path. It is opposed to be used in some other way (added to some
/// collection, passed as a parameter, etc.).
/// \param IsCompletionHandler -- true, if parameter is a completion handler.
virtual void handleNeverCalled(const ParmVarDecl *Parameter,
const Decl *Function, const Stmt *Where,
NeverCalledReason Reason,
bool IsCalledDirectly,
bool IsCompletionHandler) {}
/// Called when the block is guaranteed to be called exactly once.
/// It means that we can be stricter with what we report on that block.
/// \param Block -- block declaration that is known to be called exactly once.
virtual void
handleBlockThatIsGuaranteedToBeCalledOnce(const BlockDecl *Block) {}
/// Called when the block has no guarantees about how many times it can get
/// called.
/// It means that we should be more lenient with reporting warnings in it.
/// \param Block -- block declaration in question.
virtual void handleBlockWithNoGuarantees(const BlockDecl *Block) {}
};
/// Check given CFG for 'called once' parameter violations.
///
/// It traverses the function and tracks how such parameters are used.
/// It detects two main violations:
/// * parameter is called twice
/// * parameter is not called
///
/// \param AC -- context.
/// \param Handler -- a handler for found violations.
/// \param CheckConventionalParameters -- true, if we want to check parameters
/// not explicitly marked as 'called once', but having the same requirements
/// according to conventions.
void checkCalledOnceParameters(AnalysisDeclContext &AC,
CalledOnceCheckHandler &Handler,
bool CheckConventionalParameters);
} // end namespace clang
#endif /* LLVM_CLANG_ANALYSIS_ANALYSES_CALLEDONCECHECK_H */