facebookarchive/prepack

Support abstract functions with simple return types

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#2514 opened on Aug 30, 2018

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 (0 comments) (0 reactions) (0 assignees)JavaScript (14,268 stars) (520 forks)batch import
enhancementhelp wantedpriority: low

Description

I need this to work:

let f = __abstract(":object", "(__f)");
global.result = f().p;

But it currently fails because the access to .p is not known to be safe. I'd like to model that the result of the call to f is a simple object where all such accesses should simply be allowed, maybe via __abstract(":object(simple)", ...).

Contributor guide

Tech stack
javascript
Domain
toolingdeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of Prepack's abstraction modelFamiliarity with JavaScript runtime semantics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue is about adding support for abstract functions with simple return types in Prepack. The proposed syntax is ` abstract(":object(simple)", ...)`. To implement, one would need to examine how Prepack currently handles abstract object types and property accesses. The relevant code likely resides in the abstract value handling files. There are no existing PRs or comments to refer to. The goal is to allow safe property access on abstract objects marked as 'simple'.