[compiler] Add support for diagnostic hints #34126
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If you have a ref that the compiler doesn't know is a ref (say, a value returned from a custom hook) and try to assign its `.current = ...`, we currently fail with a generic error that hook return values are not mutable. However, an assignment to `.current` specifically is a very strong hint that the value is likely to be a ref. So in this PR, we track the reason for the mutation and if it ends up being an error, we use it to show an additional hint to the user. See the fixture for an example of the message. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34125). * #34126 * __->__ #34125 * #34124
Hints are meant as additional information to present to the developer about an error. The first use-case here is for the suggestion to name refs with "-Ref" if we encounter a mutation that looks like it might be a ref. The original error printing used a second error detail which printed the source code twice, a hint with just extra text is less noisy.
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If you have a ref that the compiler doesn't know is a ref (say, a value returned from a custom hook) and try to assign its `.current = ...`, we currently fail with a generic error that hook return values are not mutable. However, an assignment to `.current` specifically is a very strong hint that the value is likely to be a ref. So in this PR, we track the reason for the mutation and if it ends up being an error, we use it to show an additional hint to the user. See the fixture for an example of the message. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34125). * #34126 * __->__ #34125 * #34124 DiffTrain build for [724b324](724b324)
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If you have a ref that the compiler doesn't know is a ref (say, a value returned from a custom hook) and try to assign its `.current = ...`, we currently fail with a generic error that hook return values are not mutable. However, an assignment to `.current` specifically is a very strong hint that the value is likely to be a ref. So in this PR, we track the reason for the mutation and if it ends up being an error, we use it to show an additional hint to the user. See the fixture for an example of the message. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34125). * #34126 * __->__ #34125 * #34124 DiffTrain build for [724b324](724b324)
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Hints are meant as additional information to present to the developer about an error. The first use-case here is for the suggestion to name refs with "-Ref" if we encounter a mutation that looks like it might be a ref. The original error printing used a second error detail which printed the source code twice, a hint with just extra text is less noisy. DiffTrain build for [6ffcac8](6ffcac8)
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Hints are meant as additional information to present to the developer about an error. The first use-case here is for the suggestion to name refs with "-Ref" if we encounter a mutation that looks like it might be a ref. The original error printing used a second error detail which printed the source code twice, a hint with just extra text is less noisy. DiffTrain build for [6ffcac8](6ffcac8)
This was referenced Aug 18, 2025
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Hints are meant as additional information to present to the developer about an error. The first use-case here is for the suggestion to name refs with "-Ref" if we encounter a mutation that looks like it might be a ref. The original error printing used a second error detail which printed the source code twice, a hint with just extra text is less noisy.