Merge multi-source output sourcemaps #14246
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Surprisingly, Babel allows a transformer to mark the source file of a node to allow it to be sourced from any file. When this happens, the output sourcemap will contain multiple `sources`. I didn't realize this when I created babel#14209, and this `remapping` will throw an error if the output map has multiple sources. This can be fixed by using `remapping`'s graph building API (don't pass an array). This allows us to return an input map for _any_ source file, and we just need some special handling to figure out which source is our transformed file. This actually adds a new feature, allowing us to remap these multi-source outputs. Previously, the merging would silently fail and generate a blank (no `mappings`) sourcemap. That's not great. The new behavior will properly merge the maps, provided we can figure out which source is the transformed file (which should always work, I can't think of a case it wouldn't). Fixes ampproject/remapping#159.
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Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/51177/ |
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This might help with #14132 (cc @ForbiddenEra) |
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JLHwung
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A follow-up to babel#14246. I finally thought of a case where the sourceFileName's content is fully replaced, leading to only the injected file existing in the output sourcemap. This can happen where only one output source is created, or multiple. In the single output source case, we'd incorrectly associate the mappings through the inputMap, even though none of the content actually comes from there. In the multiple source case, we'd silently fail and output empty mappings. Both cases are now fixed, with the correct remapping being done through in all possible output cases now.
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…14247) * Support merging sourcemaps when transformed file is fully replaced A follow-up to #14246. I finally thought of a case where the sourceFileName's content is fully replaced, leading to only the injected file existing in the output sourcemap. This can happen where only one output source is created, or multiple. In the single output source case, we'd incorrectly associate the mappings through the inputMap, even though none of the content actually comes from there. In the multiple source case, we'd silently fail and output empty mappings. Both cases are now fixed, with the correct remapping being done through in all possible output cases now. * Update to remapping@2.1.0 to support source location override
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Merge multi-source output sourcemaps
Surprisingly, Babel allows a transformer to mark the source file of
a node to allow it to be sourced from any file. When this happens, the
output sourcemap will contain multiple
sources. I didn't realize thiswhen I created #14209, and this
remappingwill throw an error if theoutput map has multiple sources.
This can be fixed by using
remapping's graph building API (don't passan array). This allows us to return an input map for any source file,
and we just need some special handling to figure out which source is our
transformed file.
This actually adds a new feature, allowing us to remap these
multi-source outputs. Previously, the merging would silently fail and
generate a blank (no
mappings) sourcemap. That's not great. The newbehavior will properly merge the maps, provided we can figure out which
source is the transformed file (which should always work, I can't think
of a case it wouldn't).
See the visualization of the test case.