0description.md

x and x are not caught by the Reader + continuation-based guard that checks for duplicates, because duplicates are checked when going down the tree.

Since the two x are at the same level, I get those two as values (renamed, to return), but not in the Reader context.

-- https://github.com/Kleidukos/ProtoHaskell/blob/main/src/Compiler/Renamer.hs#L198-L205

renameBinds :: PhLocalBinds ParsedName -> Renamer (PhLocalBinds Name)
renameBinds localBinds = do
  let LocalBinds binds signatures = localBinds
  renamedBinds <- traverse (mapLocM renamePhBind) binds
  -- This is where the renamedBinds are returned, but the traverse does not catch same-level duplicates
  renamedSignatures <- traverse (mapLocM renameSig) signatures
  pure $
    LocalBinds renamedBinds renamedSignatures

1source.hs

module Snippet1 where

  bar :: Int
  bar = 
    let x = "lol"
        x = "mdr" 
     in 3

2AST.hs

{ modName = Just
  ( Located
	( RealSrcSpan SrcSpanOneLine <snippet1> 2 10 18 ) "Snippet1"
  )
, modDecls =
  [ Located
	( RealSrcSpan SrcSpanOneLine <snippet1> 4 5 15 )
	( Signature
	  ( TypeSig
		( Name
		  { sort = Internal
		  , occ = OccName
			{ nameSpace = VarName
			, occNameSrcSpan = RealSrcSpan SrcSpanOneLine <snippet1> 4 5 8
			, nameFS = bar
			}
		  , uniq = Unique RenameSection 5
		  }
		)
		( Located
		  ( RealSrcSpan SrcSpanOneLine <snippet1> 4 12 15 )
		  ( PhVarTy
			( Name
			  { sort = Internal
			  , occ = OccName
				{ nameSpace = TcClsName
				, occNameSrcSpan = RealSrcSpan SrcSpanOneLine <snippet1> 4 12 15
				, nameFS = Int
				}
			  , uniq = Unique RenameSection 6
			  }
			)
		  )
		)
	  )
	)
  , Located
	( RealSrcSpan SrcSpanMultiLine <snippet1> 5 5 8 12 )
	( Binding
	  ( PatBind
		( Located
		  ( RealSrcSpan SrcSpanOneLine <snippet1> 5 5 8 )
		  ( PVar
			( Name
			  { sort = Internal
			  , occ = OccName
				{ nameSpace = VarName
				, occNameSrcSpan = RealSrcSpan SrcSpanOneLine <snippet1> 5 5 8
				, nameFS = bar
				}
			  , uniq = Unique RenameSection 7
			  }
			)
		  )
		)
		( Located
		  ( RealSrcSpan SrcSpanMultiLine <snippet1> 5 9 8 12 )
		  ( RHS
			{ expr = Located
			  ( RealSrcSpan SrcSpanMultiLine <snippet1> 6 7 8 12 )
			  ( PhLet
				( Located
				  ( RealSrcSpan SrcSpanMultiLine <snippet1> 6 11 7 20 )
				  ( LocalBinds
					[ Located
					  ( RealSrcSpan SrcSpanOneLine <snippet1> 6 11 20 )
					  ( PatBind
						( Located
						  ( RealSrcSpan SrcSpanOneLine <snippet1> 6 11 12 )
						  ( PVar
							( Name
							  { sort = Internal
							  , occ = OccName
								{ nameSpace = VarName
								, occNameSrcSpan = RealSrcSpan SrcSpanOneLine <snippet1> 6 11 12
								, nameFS = x
								}
							  , uniq = Unique RenameSection 8
							  }
							)
						  )
						)
						( Located
						  ( RealSrcSpan SrcSpanOneLine <snippet1> 6 13 20 )
						  ( RHS
							{ expr = Located
							  ( RealSrcSpan SrcSpanOneLine <snippet1> 6 15 20 )
							  ( PhLit
								( LitString "lol" )
							  )
							, localBinds = Located ( UnhelpfulSpan <no location info> )
							  ( LocalBinds [] [] )
							}
						  )
						)
					  )
					, Located
					  ( RealSrcSpan SrcSpanOneLine <snippet1> 7 11 20 )
					  ( PatBind
						( Located
						  ( RealSrcSpan SrcSpanOneLine <snippet1> 7 11 12 )
						  ( PVar
							( Name
							  { sort = Internal
							  , occ = OccName
								{ nameSpace = VarName
								, occNameSrcSpan = RealSrcSpan SrcSpanOneLine <snippet1> 7 11 12
								, nameFS = x
								}
							  , uniq = Unique RenameSection 9
							  }
							)
						  )
						)
						( Located
						  ( RealSrcSpan SrcSpanOneLine <snippet1> 7 13 20 )
						  ( RHS
							{ expr = Located
							  ( RealSrcSpan SrcSpanOneLine <snippet1> 7 15 20 )
							  ( PhLit
								( LitString "mdr" )
							  )
							, localBinds = Located ( UnhelpfulSpan <no location info> )
							  ( LocalBinds [] [] )
							}
						  )
						)
					  )
					] []
				  )
				)
				( Located
				  ( RealSrcSpan SrcSpanOneLine <snippet1> 8 11 12 )
				  ( PhLit
					( LitInt 3 )
				  )
				)
			  )
			, localBinds = Located ( UnhelpfulSpan <no location info> )
			  ( LocalBinds [] [] )
			}
		  )
		)
	  )
	)
  ]
}