fix: named macros with function syntax now infer previous macro resolve types (#1574)

[raunak-rpm]

Summary

Fixes #1574 - Named macros built with function syntax now properly infer previous macro resolve types.

Problem

When using named macros with function syntax, TypeScript could not properly infer the resolve types from previous macros:

.macro("auth", { resolve: () => ({ user: "bob" }) })
.macro("permission", (perm: string) => ({
  auth: true,
  resolve: ({ user }) => { /* user was NOT inferred - TypeScript error! */ }
}))

Root Cause

This was a TypeScript inference limitation - a circular dependency where:

1. To know the resolve parameter types, TypeScript needs MacroContext
2. To compute MacroContext, TypeScript needs to know which macros are enabled (from the function's return)
3. To infer the function's return, TypeScript needs to know the parameter types

Solution

Added a dedicated overload for function-based named macros that:

1. Computes MacroContext from ALL previous macros (assuming all are enabled)
2. Properly threads MacroContext['resolve'] to the Singleton type

This approach makes all previous macro resolves available at type-check time since we can't know which ones will be enabled until runtime.

Changes

• Added new overload for function-based named macros in Elysia.macro()
• Added dedicated object-syntax overload for clarity
• Updated implementation signature to accept functions
• Added test case demonstrating the fix

Test Results

All 1448 tests pass, including the new test case for issue #1574.

Summary by CodeRabbit

• New Features

  • Named macros now support both function and object syntax declaration forms, providing greater flexibility in macro definition.

• Tests

  • Added test validation for type inference across chained macro dependencies.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

This PR adds new method overloads for named macros to support function-syntax declarations while improving TypeScript type inference from previously defined macros. The changes enable function-based named macros to properly recognize and type-check references to prior macro contexts, fixing a type inference gap identified in issue #1574.

Changes

Cohort / File(s)	Summary
Named Macro Type System Enhancements src/index.ts	Introduces two new overloads for the macro method: one for function-syntax variants and one for object-syntax variants of named macros. Expands the second parameter type to accept `Macro
Test Coverage test/macro/macro.test.ts	Adds test case "infer previous macro resolve in function syntax (issue #1574)" that validates two chained named macros (auth and permission) where the function-syntax permission macro correctly infers the user type from the prior auth macro's resolve output.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• patch: 1.4.16 #1529: Directly related through modifications to macro method typings and overloads for named-macro support, as well as adjustments to the applyMacro behavior.

Poem

🐰 A function, a name, a type so clear,
No more shall inference disappear,
From auth to permission, resolve flows true,
Where macros chain with types brand new! 🎀

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main fix: enabling named macros with function syntax to infer previous macro resolve types, and references the specific issue #1574.
Linked Issues check	✅ Passed	The code changes implement the exact requirement from issue #1574: function-based named macros now properly infer previous macro resolve types through dedicated overloads and improved TypeScript inference.
Out of Scope Changes check	✅ Passed	All changes are scoped to fixing the named macro function syntax inference issue; modifications to src/index.ts signatures, test additions, and package.json updates are directly aligned with the stated objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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[pkg-pr-new]

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npm i https://pkg.pr.new/elysiajs/elysia@1691

commit: 37cfac1

[SaltyAom]

This looks perfect! I have no idea how did I missed this 😭

Thank you so much 😊
Let's get this publish asap!

[SaltyAom]

Hold on, this doesn't actually handle type soundness because it assume every macro is enabled

Hmm, I'll see what I can do about this

[SaltyAom]

Will have to revert this for now