[llvm-branch-commits] [lld] [NFC][ELF] Remove Symbol's unused copy constructor (PR #210615)

[Fangrui Song via llvm-branch-commits]

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@@ -78,9 +78,17 @@ class Symbol {
   // The file from which this symbol was created.
   InputFile *file;
 
-  // The default copy constructor is deleted due to atomic flags. Define one for
-  // places where no atomic is needed.
-  Symbol(const Symbol &o) { memcpy(static_cast<void *>(this), &o, sizeof(o)); }
+  // Although the copy/move constructors/assignment operators are deleted due
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MaskRay wrote:

We can delete copy ctor/copy assignment operator (prevailing in llvm), which suppress move ctor/assignment.

And trim the comment
```
  +  // Symbols are referenced by pointer throughout the linker, so an implicit
  +  // copy would create a dangerous duplicate; copy the needed members
  +  // explicitly instead. Deleting the copy operations also suppresses the
  +  // implicit move operations.
  +  Symbol(const Symbol &) = delete;
  +  Symbol &operator=(const Symbol &) = delete;
```

https://github.com/llvm/llvm-project/pull/210615