Not quite, the linkers (at least ELF and PE which I am familiar with) will "free" parts of the file (when a block needs to be reallocated because the decl code

Not quite, the linkers (at least ELF and PE which I am familiar with) will "free" parts of the file (when a block needs to be reallocated because the decl code gets too big, or when a decl is removed) and reuse them when they can. But in general, the final executable will not be the same, this is correct.