fix(@angular/build): support TypeScript isolatedDeclarations option#32349
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cexbrayat wants to merge 1 commit intoangular:mainfrom
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fix(@angular/build): support TypeScript isolatedDeclarations option#32349cexbrayat wants to merge 1 commit intoangular:mainfrom
cexbrayat wants to merge 1 commit intoangular:mainfrom
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This change allows the use of TypeScript's isolatedDeclarations compiler option by conditionally preserving the declaration and composite options when isolatedDeclarations is enabled. Previously, the Angular CLI forcefully set both declaration and composite to false, which prevented the use of isolatedDeclarations as TypeScript requires at least one of these options to be true when isolatedDeclarations is set (TS5069 error): ``` ✘ [ERROR] TS5069: Option 'isolatedDeclarations' cannot be specified without specifying option 'declaration' or option 'composite'. [plugin angular-compiler] ```
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@clydin @alan-agius4 In your opinion, can |
alan-agius4
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Jan 27, 2026
| ...compilerOptions, | ||
| noEmitOnError: false, | ||
| composite: false, | ||
| // TypeScript requires either declaration or composite to be true when isolatedDeclarations is set |
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This will most likely slow down the build since we'd be generating declarations we don't really need for an app. Also, our current setup does handles composite projects yet.
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PR Type
What kind of change does this PR introduce?
What is the current behavior?
Recently, the Angular team said on a panel that
isolatedDeclarationscan make a huge difference in build times, but we currently can't test it in the CLI.Angular CLI forcefully set both declaration and composite to false, which prevents the use of isolatedDeclarations as TypeScript requires at least one of these options to be true when isolatedDeclarations is set (TS5069 error):
What is the new behavior?
This change allows the use of TypeScript's isolatedDeclarations compiler option by conditionally preserving the declaration and composite options when isolatedDeclarations is enabled.
Does this PR introduce a breaking change?
Other information