Start porting Type records over to using classes and accessors instead of raw casting

[zturner]

Summary

Work in progress, just want to see if people agree with the general approach

[amccarth]

LGTM

include/llvm/DebugInfo/CodeView/TypeRecord.h

342

Is there always a string? If so, then you could use <= to account for the fact that there should be at least a null character to terminate an empty string.

[rnk]

We discussed further offline, but I was thinking more that this would be a merging of the records above rather than the creation of new ones. That way the reading and writing records end up more unified.

include/llvm/DebugInfo/CodeView/TypeRecord.h

 };
 
 // LF_STRING_ID
-struct StringId {
-  TypeIndex id;
+class StringId {
+public:
+  static ErrorOr<StringId> create(ArrayRef<uint8_t> Data) {
+    if (Data.size() < sizeof(Layout))
+      return object::make_error_code(object::object_error::parse_failed);
+    return StringId(Data);
+  }
+
+  TypeIndex getId() const {
+    return reinterpret_cast<const Layout*>(Buffer.data())->id;
+  }
+
+private:
+  StringId(ArrayRef<uint8_t> Data) : Buffer(Data) {}
+
+  struct Layout {
+    TypeIndex id;
+  };
+
+  ArrayRef<uint8_t> Buffer;
 };
 
 // LF_FUNC_ID
-struct FuncId {
-  TypeIndex ParentScope;
-  TypeIndex FunctionType;
-  // Name: The null-terminated name follows.
+class FuncId {
+public:
+  static ErrorOr<FuncId> create(ArrayRef<uint8_t> Data) {
+    if (Data.size() < sizeof(Layout))
+      return object::make_error_code(object::object_error::parse_failed);
+    return FuncId(Data);
+  }
+
+  TypeIndex getParentScope() const {
+    return reinterpret_cast<const Layout*>(Buffer.data())->ParentScope;
+  }
+
+  TypeIndex getFunctionType() const {
+    return reinterpret_cast<const Layout*>(Buffer.data())->FunctionType;
+  }
+
+  StringRef getName() const {
+    const uint8_t *Data = Buffer.data() + sizeof(Layout);
+    return StringRef(reinterpret_cast<const char*>(Data));
+  }
+
+private:
+  FuncId(ArrayRef<uint8_t> Data) : Buffer(Data) {}
+
+  struct Layout {
+    TypeIndex ParentScope;
+    TypeIndex FunctionType;
+    // Name: The null-terminated name follows.
+  };
+
+  ArrayRef<uint8_t> Buffer;
 };
 
 // LF_CLASS, LF_STRUCTURE, LF_INTERFACE