Function hir_expand::db::expand_speculative

pub fn expand_speculative(
    db: &dyn ExpandDatabase,
    actual_macro_call: MacroCallId,
    speculative_args: &SyntaxNode,
    token_to_map: SyntaxToken,
) -> Option<(SyntaxNode, SyntaxToken)>

This expands the given macro call, but with different arguments. This is used for completion, where we want to see what ‘would happen’ if we insert a token. The token_to_map mapped down into the expansion, with the mapped token returned.