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name: emit description: | Use when working on the Miden compiler (cargo miden, cargo-miden) and its integration test suite, debugging compiler issues or failing tests, or implementing compiler changes and you need to inspect intermediate artifacts. Covers MIDENC_EMIT (the environment-variable equivalent of --emit) for emitting WAT/HIR/MASM (and related outputs), plus MIDENC_EMIT_MACRO_EXPAND for dumping macro-expanded Rust via cargo expand for integration-test fixtures.

MIDENC Emit (Intermediate Artifacts) + Macro Expand

Quick start

• Emit all intermediate IRs (WAT + HIR + MASM) into a ir_dump directory:
  • MIDENC_EMIT=ir=ir_dump
• Emit HIR to stdout:
  • MIDENC_EMIT=hir=-
• Emit MASM to a specific file:
  • MIDENC_EMIT=masm=out.masm
• Dump macro-expanded Rust for integration tests into a ir_dump directory:
  • MIDENC_EMIT_MACRO_EXPAND=ir_dump cargo make test

MIDENC_EMIT (same syntax as --emit)

Syntax

• Set MIDENC_EMIT to a comma-delimited list of KIND[=PATH] specs, e.g.:
  • MIDENC_EMIT=wat,hir,masm
  • MIDENC_EMIT=ir=ir_dump

Useful kinds for pipeline debugging

• wat: WebAssembly text format (.wat)
• hir: Miden High-level IR (.hir)
• masm: Miden Assembly text (.masm)
• Shorthands:
  • ir: emits wat,hir,masm together (WAT + HIR + MASM)

PATH rules (practical)

• Omit =PATH to use the CWD.
• Use =DIR to emit DIR/<stem>.<ext> for each requested output type:
  • Example: MIDENC_EMIT=ir=target/emit writes target/emit/<stem>.wat, target/emit/<stem>.hir, target/emit/<stem>.masm.
• Use =- to write textual outputs to stdout (e.g. hir=-, wat=-, masm=-).
  • Note: ir=- is invalid; ir expects a directory (or no path).
• Use =FILE to write a single output to a specific file path:
  • Example: MIDENC_EMIT=hir=my_dump.hir.

MIDENC_EMIT_MACRO_EXPAND (integration tests only)

When you need to see the actual Rust code after macros have expanded (helpful when debugging fixtures that use proc-macros, attribute macros, derives, or cfg-gated code), enable macro expansion dumps.

Behavior

• If MIDENC_EMIT_MACRO_EXPAND is unset: nothing happens.
• If set to an empty value or 1: writes *.expanded.rs files into the current working directory.
• If set to any other non-empty value: treats it as an output directory (created if missing).
• The integration test harness runs cargo expand and writes one file per fixture/test:
  • <test_name>.expanded.rs

Debugging workflow (recommended)

1. Reproduce on a single test case if possible.
2. Emit intermediate artifacts to a dedicated folder:
   • MIDENC_EMIT=ir=target/emit/<case> ...
3. If the failing test involves Rust fixtures/macros:
   • MIDENC_EMIT_MACRO_EXPAND=target/expand/<case> ...