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merged 3 commits into from
Jun 18, 2025
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[compiler] Docs describing new inference model #33533

merged 3 commits into from
Jun 18, 2025

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@josephsavona josephsavona commented Jun 14, 2025 •
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This was referenced Jun 14, 2025
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@github-actions github-actions bot added the React Core Team Opened by a member of the React Core Team label Jun 14, 2025
josephsavona
josephsavona commented Jun 14, 2025
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compiler/packages/babel-plugin-react-compiler/src/Inference/MUTABILITY_ALIASING_MODEL.md Outdated

The goal of mutability and aliasing inference is to understand the set of instructions that create/modify a, b, and c.

In code, the mutability and aliasing model is compromised of the following. More details about each pass follow below.
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WIP, the "more details" is not there yet

@josephsavona josephsavona force-pushed the pr33533 branch 2 times, most recently from 156b7a9 to 8bbf0f3 Compare June 14, 2025 00:56
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josephsavona
josephsavona commented Jun 16, 2025
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compiler/packages/babel-plugin-react-compiler/src/Inference/MUTABILITY_ALIASING_MODEL.md
MutateFrozen y error=...
```

### Corollary: Transitivity of Assign/Alias/CreateFrom/Capture
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@mofeiZ we touched on this the other day, i still need to add tests for all these cases but sharing the doc early

This was referenced Jun 16, 2025
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josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Copy fixtures affected by new inference (#33495)
df080d2 
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33495).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* #33513
* #33512
* #33504
* #33500
* #33497
* #33496
* __->__ #33495
* #33494
* #33572
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Update fixtures for new inference (#33496)
0cf6d0c 
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33496).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* #33513
* #33512
* #33504
* #33500
* #33497
* __->__ #33496
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Enable new inference by default (#33497)
90ccbd7 
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33497).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* #33513
* #33512
* #33504
* #33500
* __->__ #33497
* #33496
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Fix AnalyzeFunctions to fully reset context identifiers (#…
7c28c15 
…33500)

AnalyzeFunctions had logic to reset the mutable ranges of context
variables after visiting inner function expressions. However, there was
a bug in that logic: InferReactiveScopeVariables makes all the
identifiers in a scope point to the same mutable range instance. That
meant that it was possible for a later function expression to indirectly
cause an earlier function expressions' context variables to get a
non-zero mutable range.

The fix is to not just reset start/end of context var ranges, but assign
a new range instance. Thanks for the help on debugging, @mofeiZ!

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33500).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* #33513
* #33512
* #33504
* __->__ #33500
* #33497
* #33496
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[commit] Better error message for invalid hoisting (#33504)
7b67dc9 
We're already tracking which variables are hoisted context variables, so
if we see a mutation of a frozen value we can emit a custom error
message to help users identify the problem.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33504).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* #33513
* #33512
* __->__ #33504
* #33500
* #33497
* #33496
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] FunctionExpression context locations point to first refere…
e081cb3 
…nce (#33512)

This has always been awkward: `FunctionExpression.context` places have
locations set to the declaration of the identifier, whereas other
references have locations pointing to the reference itself. Here, we
update context operands to have their location point to the first
reference of that variable within the function.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33512).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* #33513
* __->__ #33512
* #33504
* #33500
* #33497
* #33496
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Improve error message for mutating hook args/return (#33513)
b067c6f 
The previous error message was generic, because the old style function
signature didn't support a way to specify a reason alongside a freeze
effect. This meant we could only say why a value was frozen for
instructions, but not hooks which use function signatures. By defining a
new aliasing signature for custom hooks we can specify a reason and
provide a better error message.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33513).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* __->__ #33513
@josephsavona josephsavona force-pushed the pr33533 branch 2 times, most recently from f48b99c to 730cf6a Compare June 18, 2025 22:10
@josephsavona josephsavona mentioned this pull request Jun 18, 2025
Merged
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] update fixtures (#33573)
7ce2a63 
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33573).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* #33514
* __->__ #33573
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[commit] Improve error for hoisting violations (#33514)
8f4ce72 
The previous error for hoisting violations pointed only to the variable
declaration, but didn't show where the value was accessed before that
declaration. We now track where each hoisted variable is first accessed
and report two errors, one for the reference and one for the
declaration. When we improve our diagnostic infra to support reporting
errors at multiple locations we can merge these into a single conceptual
error.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33514).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* #33518
* __->__ #33514
* #33573
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Fix infinite loop due to uncached applied signatures (#33518)
81d8115 
When we apply new aliasing signatures we can generate new temporaries,
which causes the abstract memory model to not converge. The fix is to
make sure we cache the applications of these signatures.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33518).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* #33522
* __->__ #33518
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Repro for case of lost precision in new inference (#33522)
0e7cdeb 
In comparing compilation output of the old/new inference models I found
this case (heavily distilled into a fixture). Roughly speaking the
scenario is:

* Create a mutable object `x`
* Extract part of that object and pass it to a hook/jsx so that _part_
becomes frozen
* Mutate `x`, even indirectly.

In the old model we can still independently memoize the value from the
middle step, since we assume that part of the larger value is not
changing. In the new model, the mutation from the later step effectively
overrides the freeze effect in step 2, and considers the value to have
changed later anyway.

We've already rolled out and vetted the previous behavior, confirming
that the heuristic of "that part of the mutable object is fozen now" is
generally safe. I'll fix in a follow-up.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33522).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* #33526
* __->__ #33522
* #33518
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] moduleTypeProvider support for aliasing signatures (#33526)
34179fe 
This allows us to type things like `nullthrows()` or `identity()`
functions where the return type is polymorphic on the input.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33526).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* __->__ #33526
* #33522
* #33518
@josephsavona
[compiler] More readable alias signature declarations
2a5f77c 
Now that we have support for defining aliasing signatures in moduleTypeProvider, which uses string names for receiver/args/returns/etc, we can reuse that same form for builtin declarations. The declarations are written in the unparsed form and than parsed/validated when registered (in the addFunction/addHook call).

This also required flushing out configs/schemas for more effect types.
@josephsavona
[compiler] Rename InferFunctionExprAliasingEffectsSignature
ebc2f6b
@josephsavona
[compiler] Docs describing new inference model
5ceb795 
Start of docs describing the effects and the inference rules.
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] More readable alias signature declarations (#33530)
4335f69 
Now that we have support for defining aliasing signatures in
moduleTypeProvider, which uses string names for
receiver/args/returns/etc, we can reuse that same form for builtin
declarations. The declarations are written in the unparsed form and than
parsed/validated when registered (in the addFunction/addHook call).

This also required flushing out configs/schemas for more effect types.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33530).
* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* __->__ #33530
josephsavona added a commit that referenced this pull request Jun 18, 2025
@josephsavona
[compiler] Rename InferFunctionExprAliasingEffectsSignature (#33532)
7ceb100 
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33532).
* #33571
* #33558
* #33547
* #33543
* #33533
* __->__ #33532
* #33530
@josephsavona josephsavona merged commit 4f543f3 into main Jun 18, 2025
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@vercel-release-bot vercel-release-bot mentioned this pull request Jun 20, 2025
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@eps1lon eps1lon mentioned this pull request Jun 20, 2025
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