How do unquote sigils?

Questions / Help
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1

I have some AST rewriting code (using Sourceror) that has started failing in Elixir 1.18 – I believe because unquote has become stricter about valid AST, whereas in earlier versions it was only an issue within macros.

The issue is that it’s trying to generate code containing a ~D[...] sigil. It works in Elixir 1.17:

iex(1)> quote do: unquote(~D[2025-01-07])
~D[2025-01-07]

But not in 1.18:

iex(1)> quote do: unquote(~D[2025-01-07])
** (ArgumentError) tried to unquote invalid AST: ~D[2025-01-07]
Did you forget to escape term using Macro.escape/1?
    (elixir 1.18.1) src/elixir_quote.erl:542: :elixir_quote.argument_error/1
    iex:1: (file)

I can use Macro.escape as suggested, but this inserts the date as a raw map instead of a sigil. This works, but doesn’t look great in the generated code:

iex(2)> quote do: unquote(Macro.escape(~D[2025-01-07]))
{:%{}, [],
 [__struct__: Date, calendar: Calendar.ISO, day: 7, month: 1, year: 2025]}

Is there some way to end up with a call to the ~D macro in the generated code, rather than the resulting struct/map?

2

The quote/unquote has nothing to do with how the final generated code looks like. They’re just means of generating AST/injecting given AST in the resulting AST. You’d need to figure out the correct AST you want to return for sourceror:

iex(1)> quote do: ~D[2024-12-12]
{:sigil_D, [delimiter: "[", context: Elixir, imports: [{2, Kernel}]],
 [{:<<>>, [], ["2024-12-12"]}, []]}

Depending on what input you actually have you can build that AST for the return value.

iex(1)> quote do: unquote(~D[2025-01-07])
~D[2025-01-07]

This here is basically a noop. It does/did nothing.

3

The quote/unquote has nothing to do with how the final generated code looks like. They’re just means of generating AST/injecting given AST in the resulting AST. You’d need to figure out the correct AST you want to return for sourceror:

iex(1)> quote do: ~D[2024-12-12]
{:sigil_D, [delimiter: "[", context: Elixir, imports: [{2, Kernel}]],
 [{:<<>>, [], ["2024-12-12"]}, []]}

Thanks, that makes sense.

This here is basically a noop. It does/did nothing.

Yeah, in the real code there was a lot more stuff in the quote.