Reapply "[FlowSensitive] [StatusOr] [2/N] Add minimal model" (llvm#164040) (llvm#164305)

This reverts commit eed8d3a.

Author: fmayer

clang/include/clang/Analysis/FlowSensitive/Models/UncheckedStatusOrAccessModel.h

@@ -0,0 +1,112 @@
+//===- UncheckedStatusOrAccessModel.h -------------------------------------===//
+//
+// 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 CLANG_ANALYSIS_FLOWSENSITIVE_MODELS_UNCHECKEDSTATUSORACCESSMODEL_H
+#define CLANG_ANALYSIS_FLOWSENSITIVE_MODELS_UNCHECKEDSTATUSORACCESSMODEL_H
+
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/Analysis/FlowSensitive/CFGMatchSwitch.h"
+#include "clang/Analysis/FlowSensitive/DataflowAnalysis.h"
+#include "clang/Analysis/FlowSensitive/DataflowEnvironment.h"
+#include "clang/Analysis/FlowSensitive/MatchSwitch.h"
+#include "clang/Analysis/FlowSensitive/NoopLattice.h"
+#include "clang/Analysis/FlowSensitive/StorageLocation.h"
+#include "clang/Analysis/FlowSensitive/Value.h"
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace clang::dataflow::statusor_model {
+
+// The helper functions exported here are for use of downstream vendor
+// extensions of this model.
+
+// Match declaration of `absl::StatusOr<T>` and bind `T` to "T".
+clang::ast_matchers::DeclarationMatcher statusOrClass();
+// Match declaration of `absl::Status`.
+clang::ast_matchers::DeclarationMatcher statusClass();
+// Match declaration of `absl::internal_statusor::OperatorBase`.
+clang::ast_matchers::DeclarationMatcher statusOrOperatorBaseClass();
+clang::ast_matchers::TypeMatcher statusOrType();
+
+// Get RecordStorageLocation for the `Status` contained in the `StatusOr`
+RecordStorageLocation &locForStatus(RecordStorageLocation &StatusOrLoc);
+// Get the StorageLocation for the OK boolean in the `Status`
+StorageLocation &locForOk(RecordStorageLocation &StatusLoc);
+// Get the OK boolean in the `Status`, and initialize it if necessary.
+BoolValue &valForOk(RecordStorageLocation &StatusLoc, Environment &Env);
+// Get synthetic fields for the types modelled by
+// `UncheckedStatusOrAccessModel`.
+llvm::StringMap<QualType> getSyntheticFields(QualType Ty, QualType StatusType,
+                                             const CXXRecordDecl &RD);
+
+// Initialize the synthetic fields of the `StatusOr`.
+// N.B. if it is already initialized, the value gets reset.
+BoolValue &initializeStatusOr(RecordStorageLocation &StatusOrLoc,
+                              Environment &Env);
+// Initialize the synthetic fields of the `Status`.
+// N.B. if it is already initialized, the value gets reset.
+BoolValue &initializeStatus(RecordStorageLocation &StatusLoc, Environment &Env);
+
+bool isRecordTypeWithName(QualType Type, llvm::StringRef TypeName);
+// Return true if `Type` is instantiation of `absl::StatusOr<T>`
+bool isStatusOrType(QualType Type);
+// Return true if `Type` is `absl::Status`
+bool isStatusType(QualType Type);
+
+// Get `QualType` for `absl::Status`, or default-constructed
+// QualType if it does not exist.
+QualType findStatusType(const ASTContext &Ctx);
+
+struct UncheckedStatusOrAccessModelOptions {};
+
+// Dataflow analysis that discovers unsafe uses of StatusOr values.
+class UncheckedStatusOrAccessModel
+    : public DataflowAnalysis<UncheckedStatusOrAccessModel, NoopLattice> {
+public:
+  explicit UncheckedStatusOrAccessModel(ASTContext &Ctx, Environment &Env);
+
+  static Lattice initialElement() { return {}; }
+
+  void transfer(const CFGElement &Elt, Lattice &L, Environment &Env);
+
+private:
+  CFGMatchSwitch<TransferState<Lattice>> TransferMatchSwitch;
+};
+
+using LatticeTransferState =
+    TransferState<UncheckedStatusOrAccessModel::Lattice>;
+
+// Extend the Builder with the transfer functions for
+// `UncheckedStatusOrAccessModel`. This is useful to write downstream models
+// that extend the model.
+CFGMatchSwitch<LatticeTransferState>
+buildTransferMatchSwitch(ASTContext &Ctx,
+                         CFGMatchSwitchBuilder<LatticeTransferState> Builder);
+
+class UncheckedStatusOrAccessDiagnoser {
+public:
+  explicit UncheckedStatusOrAccessDiagnoser(
+      UncheckedStatusOrAccessModelOptions Options = {});
+
+  llvm::SmallVector<SourceLocation> operator()(
+      const CFGElement &Elt, ASTContext &Ctx,
+      const TransferStateForDiagnostics<UncheckedStatusOrAccessModel::Lattice>
+          &State);
+
+private:
+  CFGMatchSwitch<const Environment, llvm::SmallVector<SourceLocation>>
+      DiagnoseMatchSwitch;
+};
+
+} // namespace clang::dataflow::statusor_model
+
+#endif // CLANG_ANALYSIS_FLOWSENSITIVE_MODELS_UNCHECKEDSTATUSORACCESSMODEL_H

clang/lib/Analysis/FlowSensitive/Models/CMakeLists.txt

@@ -1,6 +1,7 @@
 add_clang_library(clangAnalysisFlowSensitiveModels
   ChromiumCheckModel.cpp
   UncheckedOptionalAccessModel.cpp
+  UncheckedStatusOrAccessModel.cpp
 
   LINK_LIBS
   clangAnalysis