Hello everyone! 👋 shadow-cljs outputs source-maps in “sections” format but Sentry (error tracking SaaS) fails to parse it. The “sections” format looks like:
{
version : 3,
file: "app.js",
sections: [
{ offset: {line:0, column:0}, url: "url_for_part1.map" }
{ offset: {line:100, column:10}, map:
{
version : 3,
file: "section.js",
sources: ["foo.js", "bar.js"],
names: ["src", "maps", "are", "fun"],
mappings: "AAAA,E;;ABCDE;"
}
}
],
}{
"version" : 3,
"file": "out.js",
"sourceRoot": "",
"sources": ["foo.js", "bar.js"],
"sourcesContent": [null, null],
"names": ["src", "maps", "are", "fun"],
"mappings": "A,AAAB;;ABCDE;"
}{:shadow.build/stage :flush} build hook.
However, the naive merging sections back to the top-level map didn’t work - it went past initial sentry’s parsing error "Sourcemap was invalid or not parseable" but then it hit errors like "Invalid location in sourcemap: (37101, 117)".
my naive (not working) attempt:
(defn flatten-source-map [path]
(let [source-map (-> (io/file path)
slurp
ch/decode)
sections (get source-map "sections")]
(->> sections
(reduce (fn [acc section]
(-> acc
(update-in ["names"] (fnil into []) (get-in section ["map" "names"]))
(update-in ["mappings"] #(if (not-empty %)
(str % ";" (get-in section ["map" "mappings"]))
(get-in section ["map" "mappings"])))
(update-in ["sources"] (fnil into []) (get-in section ["map" "sources"]))
(update-in ["sourcesContent"] (fnil into []) (get-in section ["map" "sourcesContent"]))))
(dissoc source-map "sections"))
ch/encode
(spit path))))
(defn shadow-cljs-after-build-hook
{:shadow.build/stage :flush}
[build-state]
(let [{:shadow.build/keys [config mode]
:shadow.build.modules/keys [module-order]} build-state
{:keys [output-dir]} config
filename (-> module-order
first
name
(str ".js.map"))
path (str output-dir "/" filename)]
(when (= :release mode)
(println "shadow-cljs-after-build-hook running (flatten-source-map " path ")")
(flatten-source-map path)))
build-state)