Add ad hoc script doc.sh to help read the output of [make doc].

Makefile

@@ -118,7 +118,7 @@ DOC    = $(DOCDIR)/inferno/index.html
 doc:
 	@ rm -rf _build/default/_doc
 	@ dune clean
-	@ dune build @doc
+	@ dune build @doc 2>&1 | ./doc.sh
 	@ echo "You can view the documentation by typing 'make view'".
 
 .PHONY: view

doc.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+set -euo pipefail
+shopt -s extglob
+
+# This script helps make sense of the error messages produced by odoc.
+
+# A list of missing modules.
+missing=""
+
+while read line
+do
+  buffer="$line"
+  case "$line" in
+  File*client*:)
+    # A warning about the directory client/. Stop.
+    echo "Skipping all warnings about client/."
+    break
+    ;;
+  File*:)
+    read line
+    buffer="$buffer$line"
+    case "$line" in
+
+    "Warning: Couldn't find the following modules:")
+      read line
+      # A warning that some modules could not be found.
+      # Accumulate the names of the missing modules.
+      missing="$missing $line"
+      ;;
+
+    "Warning: Failed to lookup type unresolvedroot(Stdlib)"*)
+      # A warning about Stdlib. Skip.
+      echo "Skipping warnings about Stdlib."
+      ;;
+
+    "Warning: While"*)
+      read line
+      buffer="$buffer$line"
+      case "$line" in
+      "Failed to lookup type unresolvedroot(Stdlib)"*)
+        # A multi-line warning about Stdlib. Skip.
+        echo "Skipping warnings about Stdlib."
+        ;;
+      *)
+        # Another kind of warning. Echo.
+        echo "$buffer"
+        ;;
+      esac
+      ;;
+
+    *)
+      # Another kind of warning. Echo.
+      echo "$buffer"
+      ;;
+    esac
+    ;;
+
+  *)
+    echo "$buffer"
+    ;;
+  esac
+done
+
+# Show the missing modules.
+echo "Missing modules:"
+echo "$missing" | sed -e 's/^ *//' | tr " " "\n" | sort | uniq