From cafb8b4ff2c38f81e65f97193eb1d8d16c581522 Mon Sep 17 00:00:00 2001
From: Sam Estep <sam@samestep.com>
Date: Wed, 29 Jun 2022 19:19:58 +0000
Subject: [PATCH] [clang][dataflow] Use diagnosis API in optional checker

Followup to D127898. This patch updates `bugprone-unchecked-optional-access` to use the new `diagnoseCFG` function instead of just looking at the exit block.

A followup to this will update the optional model itself to use a noop lattice rather than redundantly computing the diagnostics in both phases of the analysis.

Reviewed By: ymandel, sgatev, gribozavr2, xazax.hun

Differential Revision: https://reviews.llvm.org/D128352
---
 .../bugprone/UncheckedOptionalAccessCheck.cpp      | 33 +++++++++++-----------
 .../Analysis/FlowSensitive/DataflowAnalysis.h      | 29 +++++++++++++++----
 2 files changed, 41 insertions(+), 21 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
index 07fb19f..9766450 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
@@ -23,6 +23,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/Any.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Error.h"
 #include <memory>
 #include <vector>
@@ -32,12 +33,13 @@ namespace tidy {
 namespace bugprone {
 using ast_matchers::MatchFinder;
 using dataflow::SourceLocationsLattice;
+using dataflow::UncheckedOptionalAccessDiagnoser;
 using dataflow::UncheckedOptionalAccessModel;
 using llvm::Optional;
 
 static constexpr llvm::StringLiteral FuncID("fun");
 
-static Optional<SourceLocationsLattice>
+static Optional<std::vector<SourceLocation>>
 analyzeFunction(const FunctionDecl &FuncDecl, ASTContext &ASTCtx) {
   using dataflow::ControlFlowContext;
   using dataflow::DataflowAnalysisState;
@@ -52,23 +54,22 @@ analyzeFunction(const FunctionDecl &FuncDecl, ASTContext &ASTCtx) {
       std::make_unique<dataflow::WatchedLiteralsSolver>());
   dataflow::Environment Env(AnalysisContext, FuncDecl);
   UncheckedOptionalAccessModel Analysis(ASTCtx);
+  UncheckedOptionalAccessDiagnoser Diagnoser;
+  std::vector<SourceLocation> Diagnostics;
   Expected<std::vector<Optional<DataflowAnalysisState<SourceLocationsLattice>>>>
-      BlockToOutputState =
-          dataflow::runDataflowAnalysis(*Context, Analysis, Env);
+      BlockToOutputState = dataflow::runDataflowAnalysis(
+          *Context, Analysis, Env,
+          [&ASTCtx, &Diagnoser,
+           &Diagnostics](const Stmt *Stmt,
+                         const DataflowAnalysisState<SourceLocationsLattice>
+                             &State) mutable {
+            auto StmtDiagnostics = Diagnoser.diagnose(ASTCtx, Stmt, State.Env);
+            llvm::move(StmtDiagnostics, std::back_inserter(Diagnostics));
+          });
   if (!BlockToOutputState)
     return llvm::None;
-  assert(Context->getCFG().getExit().getBlockID() < BlockToOutputState->size());
 
-  const Optional<DataflowAnalysisState<SourceLocationsLattice>>
-      &ExitBlockState =
-          (*BlockToOutputState)[Context->getCFG().getExit().getBlockID()];
-  // `runDataflowAnalysis` doesn't guarantee that the exit block is visited;
-  // for example, when it is unreachable.
-  // FIXME: Diagnose violations even when the exit block is unreachable.
-  if (!ExitBlockState)
-    return llvm::None;
-
-  return std::move(ExitBlockState->Lattice);
+  return Diagnostics;
 }
 
 void UncheckedOptionalAccessCheck::registerMatchers(MatchFinder *Finder) {
@@ -97,9 +98,9 @@ void UncheckedOptionalAccessCheck::check(
   if (FuncDecl->isTemplated())
     return;
 
-  if (Optional<SourceLocationsLattice> Errors =
+  if (Optional<std::vector<SourceLocation>> Errors =
           analyzeFunction(*FuncDecl, *Result.Context))
-    for (const SourceLocation &Loc : Errors->getSourceLocations())
+    for (const SourceLocation &Loc : *Errors)
       diag(Loc, "unchecked access to optional value");
 }
 
diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h
index f4d6a22..40ac95b 100644
--- a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h
+++ b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h
@@ -109,14 +109,33 @@ template <typename LatticeT> struct DataflowAnalysisState {
 /// dataflow analysis states that model the respective basic blocks. The
 /// returned vector, if any, will have the same size as the number of CFG
 /// blocks, with indices corresponding to basic block IDs. Returns an error if
-/// the dataflow analysis cannot be performed successfully.
+/// the dataflow analysis cannot be performed successfully. Otherwise, calls
+/// `PostVisitStmt` on each statement with the final analysis results at that
+/// program point.
 template <typename AnalysisT>
 llvm::Expected<std::vector<
     llvm::Optional<DataflowAnalysisState<typename AnalysisT::Lattice>>>>
-runDataflowAnalysis(const ControlFlowContext &CFCtx, AnalysisT &Analysis,
-                    const Environment &InitEnv) {
-  auto TypeErasedBlockStates =
-      runTypeErasedDataflowAnalysis(CFCtx, Analysis, InitEnv);
+runDataflowAnalysis(
+    const ControlFlowContext &CFCtx, AnalysisT &Analysis,
+    const Environment &InitEnv,
+    std::function<void(const Stmt *, const DataflowAnalysisState<
+                                         typename AnalysisT::Lattice> &)>
+        PostVisitStmt = nullptr) {
+  std::function<void(const Stmt *, const TypeErasedDataflowAnalysisState &)>
+      PostVisitStmtClosure = nullptr;
+  if (PostVisitStmt != nullptr) {
+    PostVisitStmtClosure = [&PostVisitStmt](
+                               const Stmt *Stmt,
+                               const TypeErasedDataflowAnalysisState &State) {
+      auto *Lattice =
+          llvm::any_cast<typename AnalysisT::Lattice>(&State.Lattice.Value);
+      PostVisitStmt(Stmt, DataflowAnalysisState<typename AnalysisT::Lattice>{
+                              *Lattice, State.Env});
+    };
+  }
+
+  auto TypeErasedBlockStates = runTypeErasedDataflowAnalysis(
+      CFCtx, Analysis, InitEnv, PostVisitStmtClosure);
   if (!TypeErasedBlockStates)
     return TypeErasedBlockStates.takeError();
 
-- 
2.7.4