Move package-relative path calculation under context.getPackageForModule
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Differential Revision: D56788884
…dule` Summary: During resolution using `package.json#exports` or the `browser` spec, we need package-relative subpaths of resolution candidates to check against these export/redirect maps. Currently, we derive these using (pseudo code): ``` const absolutePathOfPackageRoot = context.getPackageForModule(absolutePathOfCandidate).rootPath; const packageRelativePath = path.relative(absolutePathOfPackageRoot, absolutePathOfCandidate); ``` However, this implicitly assumes that both paths are either real, or traverse the same set of symlinks, so that the former is a prefix of the latter. If `getPackageForModule` returned `rootPath: fs.realpath(packageRoot)`, this assumption would not hold. Eg: if `/workspace-root/pgk-a/foo.js` imports `pkg-b/bar.js`, we will try a candidate `/workspace-root/node_modules/pkg-b/bar.js`, but `node_modles/pkg-b` may be a symlink to `/workspace-root/pkg-b`, and `path.relative(realPackageRoot, candidate)` will give `../node_modules/pkg-b/bar.js`, which will not match against an export map, though it represents the same location on the filesystem. Instead, we move the calculation of `packageRelativePath` inside `getPackageForModule` and close to implementation of the package search, where we know that the `path.relative` call is safe under the current implementation, and allowing an alternative implementation to use an alternative mechanism. This is in preparation for a new implementation of `getClosestPackage`, which currently dominates resolution time, using `FileSystem`, which will natively return only *real* paths. Differential Revision: D56823091
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Summary:
During resolution using
package.json#exportsor thebrowserspec, we need package-relative subpaths of resolution candidates to check against these export/redirect maps.Currently, we derive these using (pseudo code):
However, this implicitly assumes that both paths are either real, or traverse the same set of symlinks, so that the former is a prefix of the latter. If
getPackageForModulereturnedrootPath: fs.realpath(packageRoot), this assumption would not hold.Eg: if
/workspace-root/pgk-a/foo.jsimportspkg-b/bar.js, we will try a candidate/workspace-root/node_modules/pkg-b/bar.js, butnode_modles/pkg-bmay be a symlink to/workspace-root/pkg-b, andpath.relative(realPackageRoot, candidate)will give../node_modules/pkg-b/bar.js, which will not match against an export map, though it represents the same location on the filesystem.Instead, we move the calculation of
packageRelativePathinsidegetPackageForModuleand close to implementation of the package search, where we know that thepath.relativecall is safe under the current implementation, and allowing an alternative implementation to use an alternative mechanism.This is in preparation for a new implementation of
getClosestPackage, which currently dominates resolution time, usingFileSystem, which will natively return only real paths.Differential Revision: D56823091