[clang] Introduce intra-procedural lifetime analysis in Clang (PR #142313)

[Gábor Horváth via cfe-commits]

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@@ -0,0 +1,753 @@
+#include "clang/Analysis/Analyses/LifetimeSafety.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/AST/Type.h"
+#include "clang/Analysis/AnalysisDeclContext.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/Analysis/FlowSensitive/DataflowWorklist.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/ImmutableMap.h"
+#include "llvm/ADT/ImmutableSet.h"
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/TimeProfiler.h"
+#include <cstdint>
+
+namespace clang {
+namespace {
+
+/// Represents the storage location being borrowed, e.g., a specific stack
+/// variable.
+struct AccessPath {
+  const clang::ValueDecl *D;
+
+  enum class Kind : uint8_t {
+    StackVariable,
+    Temporary,    // TODO: Handle.
+    Field,        // TODO: Handle like `s.y`.
+    Heap,         // TODO: Handle.
+    ArrayElement, // TODO: Handle.
+    Static,       // TODO: Handle.
+  };
+
+  Kind PathKind;
+
+  AccessPath(const clang::ValueDecl *D, Kind K) : D(D), PathKind(K) {}
+};
+
+/// A generic, type-safe wrapper for an ID, distinguished by its `Tag` type.
+/// Used for giving ID to loans and origins.
+template <typename Tag> struct ID {
+  uint32_t Value = 0;
+
+  bool operator==(const ID<Tag> &Other) const { return Value == Other.Value; }
+  bool operator!=(const ID<Tag> &Other) const { return !(*this == Other); }
+  bool operator<(const ID<Tag> &Other) const { return Value < Other.Value; }
+  ID<Tag> &operator++() {
+    ++Value;
+    return *this;
+  }
+  void Profile(llvm::FoldingSetNodeID &IDBuilder) const {
+    IDBuilder.AddInteger(Value);
+  }
+};
+
+template <typename Tag>
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, ID<Tag> ID) {
+  return OS << ID.Value;
+}
+
+struct LoanTag {};
+struct OriginTag {};
+
+using LoanID = ID<LoanTag>;
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Xazax-hun wrote:

I think you could even do `using LoanID = ID<struct LoanTag>;`, so no separate definition is required for these tags. 

https://github.com/llvm/llvm-project/pull/142313