[compiler] Deprecate noEmit, add outputMode #35112
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Comparing: 4cf770d...2782d93 Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
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Nov 20, 2025
| if (programContext.hasModuleScopeOptOut) { | ||
| return null; | ||
| } else if (programContext.opts.noEmit) { | ||
| } else if (programContext.opts.outputMode === 'lint') { |
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i honestly don't quite get the point of this case, i'm just preserving what we did before
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I think this might have been the IDE prototype @poteto built to highlight effect dependencies
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Nov 20, 2025
| ## Error | ||
|
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| ``` | ||
| Found 1 error: |
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This preserves the existing error (previous test was @noEmit). Also see the infer-effect-deps-with-rule-violation-use-memo-opt-in.js which uses outputMode:'client', and does actually infer effect deps
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Just a quick poc: * Inline useState when the initializer is known to not be a function. The heuristic could be improved but will handle a large number of cases already. * Prune effects * Prune useRef if the ref is unused, by pruning 'ref' props on primitive components. Then DCE does the rest of the work - with a small change to allow `useRef()` calls to be dropped since function calls aren't normally eligible for dropping. * Prune event handlers, by pruning props whose names start w "on" from primitive components. Then DCE removes the functions themselves. Per the fixture, this gets pretty far. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/35102). * #35112 * __->__ #35102
This deprecates the `noEmit: boolean` flag and adds `outputMode: 'client' | 'client-no-memo' | 'ssr' | 'lint'` as the replacement. OutputMode defaults to null and takes precedence if specified, otherwise we use 'client' mode for noEmit=false and 'lint' mode for noEmit=true. Key points: * Retrying failed compilation switches from 'client' mode to 'client-no-memo' * Validations are enabled behind Environment.proto.shouldEnableValidations, enabled for all modes except 'client-no-memo'. Similar for dropping manual memoization. * OptimizeSSR is now gated by the outputMode==='ssr', not a feature flag * Creation of reactive scopes, and related codegen logic, is now gated by outputMode==='client'
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Just a quick poc: * Inline useState when the initializer is known to not be a function. The heuristic could be improved but will handle a large number of cases already. * Prune effects * Prune useRef if the ref is unused, by pruning 'ref' props on primitive components. Then DCE does the rest of the work - with a small change to allow `useRef()` calls to be dropped since function calls aren't normally eligible for dropping. * Prune event handlers, by pruning props whose names start w "on" from primitive components. Then DCE removes the functions themselves. Per the fixture, this gets pretty far. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/35102). * #35112 * __->__ #35102 DiffTrain build for [4cf770d](4cf770d)
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Just a quick poc: * Inline useState when the initializer is known to not be a function. The heuristic could be improved but will handle a large number of cases already. * Prune effects * Prune useRef if the ref is unused, by pruning 'ref' props on primitive components. Then DCE does the rest of the work - with a small change to allow `useRef()` calls to be dropped since function calls aren't normally eligible for dropping. * Prune event handlers, by pruning props whose names start w "on" from primitive components. Then DCE removes the functions themselves. Per the fixture, this gets pretty far. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/35102). * #35112 * __->__ #35102 DiffTrain build for [4cf770d](4cf770d)
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This deprecates the `noEmit: boolean` flag and adds `outputMode: 'client' | 'client-no-memo' | 'ssr' | 'lint'` as the replacement. OutputMode defaults to null and takes precedence if specified, otherwise we use 'client' mode for noEmit=false and 'lint' mode for noEmit=true. Key points: * Retrying failed compilation switches from 'client' mode to 'client-no-memo' * Validations are enabled behind Environment.proto.shouldEnableValidations, enabled for all modes except 'client-no-memo'. Similar for dropping manual memoization. * OptimizeSSR is now gated by the outputMode==='ssr', not a feature flag * Creation of reactive scopes, and related codegen logic, is now gated by outputMode==='client' DiffTrain build for [50e7ec8](50e7ec8)
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This deprecates the `noEmit: boolean` flag and adds `outputMode: 'client' | 'client-no-memo' | 'ssr' | 'lint'` as the replacement. OutputMode defaults to null and takes precedence if specified, otherwise we use 'client' mode for noEmit=false and 'lint' mode for noEmit=true. Key points: * Retrying failed compilation switches from 'client' mode to 'client-no-memo' * Validations are enabled behind Environment.proto.shouldEnableValidations, enabled for all modes except 'client-no-memo'. Similar for dropping manual memoization. * OptimizeSSR is now gated by the outputMode==='ssr', not a feature flag * Creation of reactive scopes, and related codegen logic, is now gated by outputMode==='client' DiffTrain build for [50e7ec8](50e7ec8)
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This deprecates the
noEmit: booleanflag and addsoutputMode: 'client' | 'client-no-memo' | 'ssr' | 'lint'as the replacement. OutputMode defaults to null and takes precedence if specified, otherwise we use 'client' mode for noEmit=false and 'lint' mode for noEmit=true.Key points: