Fix links to external stdlib repos in docs, fixes #43199. (#43225)

(cherry picked from commit 3103102)

doc/make.jl

@@ -213,8 +213,9 @@ else
     )
 end
 
+const output_path = joinpath(buildroot, "doc", "_build", (render_pdf ? "pdf" : "html"), "en")
 makedocs(
-    build     = joinpath(buildroot, "doc", "_build", (render_pdf ? "pdf" : "html"), "en"),
+    build     = output_path,
     modules   = [Main, Base, Core, [Base.root_module(Base, stdlib.stdlib) for stdlib in STDLIB_DOCS]...],
     clean     = true,
     doctest   = ("doctest=fix" in ARGS) ? (:fix) : ("doctest=only" in ARGS) ? (:only) : ("doctest=true" in ARGS) ? true : false,
@@ -228,6 +229,31 @@ makedocs(
     pages     = PAGES,
 )
 
+# Update URLs to external stdlibs (JuliaLang/julia#43199)
+for (root, _, files) in walkdir(output_path), file in joinpath.(root, files)
+    endswith(file, ".html") || continue
+    str = read(file, String)
+    # Index page links, update
+    #   https://github.com/JuliaLang/julia/blob/master/stdlib/${STDLIB_NAME}-${STDLIB_COMMIT}/path/to.md
+    # to
+    #   https://github.com/JuliaLang/${STDLIB_NAME}.jl/blob/master/docs/src/index.md
+    str = replace(str, r"https://github.com/JuliaLang/julia/blob/master/stdlib/(.*)-\w{40}/(.*\.md)" =>
+                       s"https://github.com/JuliaLang/\1.jl/blob/master/\2")
+    # Link to source links, update
+    #   https://github.com/JuliaLang/julia/blob/${JULIA_COMMIT}/stdlib/${STDLIB_NAME}-${STDLIB_COMMIT}/path/to.jl#${LINES}
+    # to
+    #   https://github.com/JuliaLang/${STDLIB_NAME}.jl/blob/${STDLIB_COMMIT}/path/to.jl#${LINES}
+    str = replace(str, r"https://github\.com/JuliaLang/julia/blob/\w{40}/stdlib/(.*)-(\w{40})/(.*\.jl#L\d+(?:-L\d+)?)" =>
+                       s"https://github.com/JuliaLang/\1.jl/blob/\2/\3")
+    # Some stdlibs are not hosted by JuliaLang
+    str = replace(str, r"(https://github\.com)/JuliaLang/(ArgTools\.jl/blob)" => s"\1/JuliaIO/\2")
+    str = replace(str, r"(https://github\.com)/JuliaLang/(LibCURL\.jl/blob)" => s"\1/JuliaWeb/\2")
+    str = replace(str, r"(https://github\.com)/JuliaLang/(SHA\.jl/blob)" => s"\1/JuliaCrypto/\2")
+    str = replace(str, r"(https://github\.com)/JuliaLang/(Tar\.jl/blob)" => s"\1/JuliaIO/\2")
+    # Write back to the file
+    write(file, str)
+end
+
 # Define our own DeployConfig
 struct BuildBotConfig <: Documenter.DeployConfig end
 function Documenter.deploy_folder(::BuildBotConfig; devurl, repo, branch, kwargs...)