TypedSyntax: a macro call inside an expression leaves the enclosing calls unmapped

[jishnub]

When a macro call appears inside an expression, the statements for the enclosing calls on that line — the ones the user wrote, not the macro's expansion — get no source node. Shape from ApproxFunBase's _default_Fun:

struct Coefs; coefficients::Vector{Float64}; end
function macroline(cf::Coefs, bs::Int)
    m = maximum(abs, cf.coefficients)
    maximum(abs, @view cf.coefficients[bs:end]) < 10m
end

Repro (TypedSyntax 1.5.4, Julia 1.13.0):

using TypedSyntax, JuliaSyntax
using JuliaSyntax: kind, sourcetext
macroline(Coefs(rand(3)), 1)
mi = only(Base.method_instances(macroline, (Coefs, Int), Base.get_world_counter()))
src, rt = TypedSyntax.code_typed1_tsn(mi)
tsn, mappings = TypedSyntax.tsn_and_mappings(mi, src, rt)
for (i, nodes) in enumerate(mappings)
    st = src.code[i]
    (st isa Core.ReturnNode || st isa Core.GotoIfNot || st isa Core.GotoNode) && continue
    println(i, "  ", st, " -> ", isempty(nodes) ? "(nothing)" : [string(kind(n), " `", sourcetext(n), "`") for n in nodes])
end

Output:

  1  Main.maximum                                 -> Identifier `maximum`
  2  Main.abs                                     -> Identifier `abs`
  3  Base.getproperty(_2, :coefficients)          -> . `cf.coefficients`
  4  _5 = (%1)(%2, %3)                            -> call `maximum(abs, cf.coefficients)`
  5  Main.:<                                      -> Identifier `<`
  6  Main.maximum                                 -> Identifier `maximum`
  7  Main.abs                                     -> Identifier `abs`
  8  _4 = Base.getproperty(_2, :coefficients)     -> . `cf.coefficients`
  9  _4                                           -> (nothing)
 10  Main.:(:)                                    -> (nothing)
 11  _4                                           -> (nothing)
 12  (lastindex)(%11)                             -> (nothing)
 13  (%10)(_3, %12)                               -> (nothing)
 14  (view)(%9, %13)                              -> (nothing)
 15  (%6)(%7, %14)                                -> (nothing)
 16  Main.:*                                      -> (nothing)
 17  _5                                           -> (nothing)
 18  (%16)(10, %17)                               -> (nothing)
 19  (%5)(%15, %18)                               -> (nothing)

The first line maps completely. On the second line only the leaf identifiers and cf.coefficients map; the @view expansion (lastindex, :, view) is understandably unmapped, but so are the calls around it that the source spells verbatim — maximum(abs, ...), <, 10m — so the whole expression comes back untyped and none of those callsites can be located in the source.

In the original (maximum(abs, @view cf.coefficients[bs:end]) < 10tol*maxabsc in ApproxFunBase, seen through Cthulhu) the outcome was slightly different: the maximum statement was attributed to the macrocall node itself rather than dropped, so the maximum callsite was located at the @view node. I could not reduce that variant to a standalone repro; the drop above is the reproducible form of the same thing.

Related: #710 (a macro call in argument position sends the enclosing call to the assignment target).

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🤖 Filed using Claude Code. The reproduction was run locally on the stated versions and the output is quoted verbatim.