Clang plugin to check that unstable types are not used in IPC.

tools/clang/plugins/CheckIPCVisitor.h

Index: tools/clang/plugins/CheckIPCVisitor.h
diff --git a/tools/clang/plugins/CheckIPCVisitor.h b/tools/clang/plugins/CheckIPCVisitor.h
new file mode 100644
index 0000000000000000000000000000000000000000..10049d6dcea98a538c1a6f6200ed2bb386274614
--- /dev/null
+++ b/tools/clang/plugins/CheckIPCVisitor.h
@@ -0,0 +1,106 @@
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This check ensures that 32/64-bit unstable types are not used in IPC.
+//
+// A type (or typedef) is unstable if it changes size between 32/ 64-bit
+// platforms. However, it's impossible to accurately identify unstable
+// typedefs, because their definitions rely on the preprocessor. For
+// example uintptr_t is either unsigned int or unsigned long.
+//
+// So we're not trying to be accurate, and just blacklisting some types
+// that are known to be unstable:
+// 1. Types: long / unsigned long (but not typedefs to)
+// 2. Typedefs: intmax_t, uintmax_t, intptr_t, uintptr_t, wint_t,
+//    size_t, rsize_t, ssize_t, ptrdiff_t, dev_t, off_t, clock_t,
+//    time_t, suseconds_t (including typedefs to)
+//
+// Additionally, templates referencing blacklisted types (e.g. vector<long>)
+// are also blacklisted.
+//
+// Blacklisted types are checked in:
+// 1. IPC::WriteParam() calls
+// 2. IPC::CheckedTuple<> specializations
+//
+
+#ifndef TOOLS_CLANG_PLUGINS_CHECKIPC_VISITOR_H_
+#define TOOLS_CLANG_PLUGINS_CHECKIPC_VISITOR_H_
+
+#include <vector>
+
+#include "clang/AST/AST.h"
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "llvm/ADT/StringSet.h"
+
+namespace chrome_checker {
+
+class CheckIPCVisitor {
+ public:
+  explicit CheckIPCVisitor(clang::CompilerInstance& compiler);
+
+  void set_context(clang::ASTContext* context) { context_ = context; }
+
+  bool should_visit_template_instantiations() const { return true; }
+
+  void BeginDecl(clang::Decl*);

[dcheng, 2016/03/07 23:44:39]

We should probably either consistently include or exclude "obvious" parameter
names (for example, compare to lines 58-64)

[Dmitry Skiba, 2016/03/08 01:16:11]

Done.

+  void EndDecl();
+  void VisitTemplateSpecializationType(clang::TemplateSpecializationType*);
+  void VisitCallExpr(clang::CallExpr*);
+
+ private:
+  // ValidateXXX functions return false if validation failed and diagnostic
+  // was reported. They return true otherwise (not applicable / validation
+  // succeeded).
+
+  bool ValidateWriteParam(const clang::CallExpr* call_expr);
+
+  bool ValidateWriteParamSignature(const clang::CallExpr* call_expr);
+
+  bool ValidateWriteParamArgument(const clang::Expr* arg_expr);
+
+  bool ValidateCheckedTuple(

[dcheng, 2016/03/07 23:44:39]

Nit: No newlines on 59, 61, 63, 71, 81, 83 to help group the methods a bit more
visually.

[Dmitry Skiba, 2016/03/08 01:16:11]

Done.

+      const clang::TemplateSpecializationType* spec);
+
+  template <typename T>
+  const T* GetParentDecl() const;
+
+  bool IsBlacklistedType(clang::QualType type) const;
+
+  bool IsBlacklistedTypedef(const clang::TypedefNameDecl* tdef) const;
+
+  struct CheckDetails {
+    clang::QualType entry_type;
+    clang::QualType exit_type;
+    llvm::SmallVector<const clang::TypedefType*, 5> typedefs;
+  };
+
+  bool CheckType(clang::QualType type, CheckDetails* details) const;
+
+  bool CheckIntegerType(clang::QualType type, CheckDetails* details) const;
+
+  bool CheckTemplateArgument(const clang::TemplateArgument& arg,
+                             CheckDetails* details) const;
+
+  void ReportCheckError(const CheckDetails& details,
+                        clang::SourceLocation loc,
+                        unsigned error);
+
+  clang::CompilerInstance& compiler_;
+  clang::ASTContext* context_;
+
+  unsigned error_write_param_bad_type_;
+  unsigned error_tuple_bad_type_;
+  unsigned error_write_param_bad_signature_;
+  unsigned note_see_here_;
+
+  std::vector<const clang::Decl*> decl_stack_;
+
+  llvm::StringSet<> blacklisted_typedefs_;
+};
+
+}  // namespace chrome_checker
+
+#endif  // TOOLS_CLANG_PLUGINS_CHECKIPC_VISITOR_H_