Merge pull request #1502 from cornfeedhobo/enhance-makefile-completion

Enhance make completion to support multiple files and gnumake

completion/available/makefile.completion.bash

@@ -1,3 +1,34 @@
-# Add completion for Makefile
-# see http://stackoverflow.com/a/38415982/1472048
-complete -W "\`grep -oE '^[a-zA-Z0-9_-]+:([^=]|$)' Makefile | sed 's/[^a-zA-Z0-9_-]*$//'\`" make
+# Bash completion for Makefile
+# Loosely adapted from http://stackoverflow.com/a/38415982/1472048
+
+_makecomplete() {
+  COMPREPLY=()
+
+  # https://www.gnu.org/software/make/manual/html_node/Makefile-Names.html
+  local files=()
+  for f in 'GNUmakefile' 'makefile' 'Makefile' ; do
+    [ -f "$f" ] && files+=("$f")
+  done
+
+  [ "${#files[@]}" -eq 0 ] && return 0
+
+  # collect all targets
+  local targets=()
+  for f in "${files[@]}" ; do
+    while IFS='' read -r line ; do
+      targets+=("$line")
+    done < <(grep -oE '^[a-zA-Z0-9_-]+:([^=]|$)' "$f" | cut -d':' -f1)
+  done
+
+  [ "${#targets[@]}" -eq 0 ] && return 0
+
+  # use the targets for completion
+  while IFS='' read -r line ; do
+    COMPREPLY+=("$line")
+  done < <(compgen -W "$(tr ' ' '\n' <<<"${targets[@]}" | sort -u)" -- "${COMP_WORDS[COMP_CWORD]}")
+
+  return 0
+}
+
+complete -o nospace -F _makecomplete make
+complete -o nospace -F _makecomplete gnumake