Creating branches/google/stable and tags/google/stable/2019-05-14 from r360103upstream/stable

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/branches/google/stable@360714 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 156 insertions, 0 deletions

diff --git a/clang-tidy/utils/ExceptionAnalyzer.h b/clang-tidy/utils/ExceptionAnalyzer.h
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+//===--- ExceptionAnalyzer.h - clang-tidy -----------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_EXCEPTION_ANALYZER_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_EXCEPTION_ANALYZER_H
+
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/StringSet.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+/// This class analysis if a `FunctionDecl` can in principle throw an
+/// exception, either directly or indirectly. It can be configured to ignore
+/// custom exception types.
+class ExceptionAnalyzer {
+public:
+  enum class State : std::int8_t {
+    Throwing = 0,    ///< The function can definitly throw given an AST.
+    NotThrowing = 1, ///< This function can not throw, given an AST.
+    Unknown = 2,     ///< This can happen for extern functions without available
+                     ///< definition.
+  };
+
+  /// Bundle the gathered information about an entity like a function regarding
+  /// it's exception behaviour. The 'NonThrowing'-state can be considered as the
+  /// neutral element in terms of information propagation.
+  /// In the case of 'Throwing' state it is possible that 'getExceptionTypes'
+  /// does not include *ALL* possible types as there is the possibility that
+  /// an 'Unknown' function is called that might throw a previously unknown
+  /// exception at runtime.
+  class ExceptionInfo {
+  public:
+    using Throwables = llvm::SmallSet<const Type *, 2>;
+    static ExceptionInfo createUnknown() {
+      return ExceptionInfo(State::Unknown);
+    }
+    static ExceptionInfo createNonThrowing() {
+      return ExceptionInfo(State::Throwing);
+    }
+
+    /// By default the exception situation is unknown and must be
+    /// clarified step-wise.
+    ExceptionInfo() : Behaviour(State::NotThrowing), ContainsUnknown(false) {}
+    ExceptionInfo(State S)
+        : Behaviour(S), ContainsUnknown(S == State::Unknown) {}
+
+    ExceptionInfo(const ExceptionInfo &) = default;
+    ExceptionInfo &operator=(const ExceptionInfo &) = default;
+    ExceptionInfo(ExceptionInfo &&) = default;
+    ExceptionInfo &operator=(ExceptionInfo &&) = default;
+
+    State getBehaviour() const { return Behaviour; }
+
+    /// Register a single exception type as recognized potential exception to be
+    /// thrown.
+    void registerException(const Type *ExceptionType);
+
+    /// Registers a `SmallVector` of exception types as recognized potential
+    /// exceptions to be thrown.
+    void registerExceptions(const Throwables &Exceptions);
+
+    /// Updates the local state according to the other state. That means if
+    /// for example a function contains multiple statements the 'ExceptionInfo'
+    /// for the final function is the merged result of each statement.
+    /// If one of these statements throws the whole function throws and if one
+    /// part is unknown and the rest is non-throwing the result will be
+    /// unknown.
+    ExceptionInfo &merge(const ExceptionInfo &Other);
+
+    /// This method is useful in case 'catch' clauses are analyzed as it is
+    /// possible to catch multiple exception types by one 'catch' if they
+    /// are a subclass of the 'catch'ed exception type.
+    /// Returns 'true' if some exceptions were filtered, otherwise 'false'.
+    bool filterByCatch(const Type *BaseClass);
+
+    /// Filter the set of thrown exception type against a set of ignored
+    /// types that shall not be considered in the exception analysis.
+    /// This includes explicit `std::bad_alloc` ignoring as separate option.
+    ExceptionInfo &
+    filterIgnoredExceptions(const llvm::StringSet<> &IgnoredTypes,
+                            bool IgnoreBadAlloc);
+
+    /// Clear the state to 'NonThrowing' to make the corresponding entity
+    /// neutral.
+    void clear();
+
+    /// References the set of known exception types that can escape from the
+    /// corresponding entity.
+    const Throwables &getExceptionTypes() const { return ThrownExceptions; }
+
+    /// Signal if the there is any 'Unknown' element within the scope of
+    /// the related entity. This might be relevant if the entity is 'Throwing'
+    /// and to ensure that no other exception then 'getExceptionTypes' can
+    /// occur. If there is an 'Unknown' element this can not be guaranteed.
+    bool containsUnknownElements() const { return ContainsUnknown; }
+
+  private:
+    /// Recalculate the 'Behaviour' for example after filtering.
+    void reevaluateBehaviour();
+
+    /// Keep track if the entity related to this 'ExceptionInfo' can in princple
+    /// throw, if it's unknown or if it won't throw.
+    State Behaviour;
+
+    /// Keep track if the entity contains any unknown elements to keep track
+    /// of the certainty of decisions and/or correct 'Behaviour' transition
+    /// after filtering.
+    bool ContainsUnknown;
+
+    /// 'ThrownException' is empty if the 'Behaviour' is either 'NotThrowing' or
+    /// 'Unknown'.
+    Throwables ThrownExceptions;
+  };
+
+  ExceptionAnalyzer() = default;
+
+  void ignoreBadAlloc(bool ShallIgnore) { IgnoreBadAlloc = ShallIgnore; }
+  void ignoreExceptions(llvm::StringSet<> ExceptionNames) {
+    IgnoredExceptions = std::move(ExceptionNames);
+  }
+
+  ExceptionInfo analyze(const FunctionDecl *Func);
+  ExceptionInfo analyze(const Stmt *Stmt);
+
+private:
+  ExceptionInfo
+  throwsException(const FunctionDecl *Func,
+                  llvm::SmallSet<const FunctionDecl *, 32> &CallStack);
+  ExceptionInfo
+  throwsException(const Stmt *St, const ExceptionInfo::Throwables &Caught,
+                  llvm::SmallSet<const FunctionDecl *, 32> &CallStack);
+
+  ExceptionInfo analyzeImpl(const FunctionDecl *Func);
+  ExceptionInfo analyzeImpl(const Stmt *Stmt);
+
+  template <typename T> ExceptionInfo analyzeDispatch(const T *Node);
+
+  bool IgnoreBadAlloc = true;
+  llvm::StringSet<> IgnoredExceptions;
+  std::map<const FunctionDecl *, ExceptionInfo> FunctionCache;
+};
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_EXCEPTION_ANALYZER_H