Fix doctests (#9225)

Haven’t tracked down when they broke. They used to work at some point
but atm they are very broken and don’t test anything.

This PR fixes the bash mess to parse the files correctly and fixes two
minor issues that creeped in by virtue of the doctests being broken.

changelog_begin
changelog_end

compiler/damlc/BUILD.bazel

@@ -320,6 +320,7 @@ daml_doc_test(
     flags = ["--no-dflags-check"],
     ignored_srcs = [
         "LibraryModules.daml",
+        "DA/Experimental/Example.daml",
         "DA/Time/Types.daml",
     ],
 )

compiler/damlc/daml-stdlib-src/DA/Map.daml

@@ -82,8 +82,8 @@ fromList list = foldl (\acc (key, value) -> insert key value acc) empty list
 --
 -- ```
 -- >>> fromListWith (++) [("A", [1]), ("A", [2]), ("B", [2]), ("B", [1]), ("A", [3])]
--- Map [("A", [1, 2, 3]), ("B", [2, 1])]
--- >>> fromListWith (++) [] == (M.empty : Map Text [Int])
+-- fromList [("A", [1, 2, 3]), ("B", [2, 1])]
+-- >>> fromListWith (++) [] == (empty : Map Text [Int])
 -- True
 -- ```
 fromListWith : Ord k => (v -> v -> v) -> [(k, v)] -> Map k v

rules_daml/daml.bzl

@@ -383,16 +383,21 @@ def daml_doc_test(
         name = name,
         data = [cpp, damlc] + srcs,
         cmd = """\
+set -eou pipefail
 CPP=$$(canonicalize_rlocation $(rootpath {cpp}))
 DAMLC=$$(canonicalize_rlocation $(rootpath {damlc}))
 FILES=($$(
   for file in {files}; do
+    IGNORED=false
     for pattern in {ignored}; do
       if [[ $$file = *$$pattern ]]; then
+        IGNORED=true
         continue
       fi
-      echo $$(canonicalize_rlocation $$i)
     done
+    if [[ $$IGNORED == "false" ]]; then
+      echo $$(canonicalize_rlocation $$file)
+    fi
   done
 ))