query: add related: combi-field + test

Add a new combination (pseudo) field "related:", which combines
"message-id" and "references"

lib/message/mu-fields.cc

@@ -38,6 +38,10 @@ Mu::combi_fields()
 		    field_from_id(Field::Id::Cc),
 		    field_from_id(Field::Id::Bcc),
 		    field_from_id(Field::Id::From)}},
+		CombiField { "related",
+		  { field_from_id(Field::Id::MessageId),
+		    field_from_id(Field::Id::References)}
+		},
 		CombiField { "",
 		  { field_from_id(Field::Id::To),
 		    field_from_id(Field::Id::Cc),

lib/tests/test-mu-store-query.cc

@@ -217,10 +217,6 @@ Boo!
 	}
 }
 
-
-
-
-
 static void
 test_related()
 {
@@ -262,7 +258,6 @@ Child
 	TempDir tdir;
 	auto store{make_test_store(tdir.path(), test_msgs, {})};
 	{
-		// direct matches
 		auto qr = store.run_query("msgid:aap@foo.bar", Field::Id::Date,
 					  QueryFlags::None);
 		g_assert_true(!!qr);
@@ -271,7 +266,6 @@ Child
 	}
 
 	{
-		// skip duplicate messages; which one is skipped is arbitrary.
 		auto qr = store.run_query("msgid:aap@foo.bar", Field::Id::Date,
 					  QueryFlags::IncludeRelated);
 		g_assert_true(!!qr);
@@ -280,7 +274,6 @@ Child
 	}
 
 	{
-		// skip duplicate messages; which one is skipped is arbitrary.
 		auto qr = store.run_query("msgid:mies@foo.bar", Field::Id::Date,
 					  QueryFlags::IncludeRelated);
 		g_assert_true(!!qr);
@@ -289,7 +282,6 @@ Child
 	}
 
 	{
-		// skip duplicate messages; which one is skipped is arbitrary.
 		auto qr = store.run_query("ref:aap@foo.bar", Field::Id::Date,
 					  QueryFlags::None);
 		g_assert_true(!!qr);
@@ -297,9 +289,15 @@ Child
 		g_assert_cmpuint(qr->size(), ==, 2);
 	}
 
+	{
+		auto qr = store.run_query("related:aap@foo.bar", Field::Id::Date,
+					  QueryFlags::None);
+		g_assert_true(!!qr);
+		g_assert_false(qr->empty());
+		g_assert_cmpuint(qr->size(), ==, 3);
+	}
 }
 
-
 static void
 test_dups_related()
 {

man/mu-query.7.org

@@ -183,6 +183,8 @@ fields at once:
 +-------------+-----------------------------------------+
 | contact     | to, cc, bcc, from                       |
 +-------------+-----------------------------------------+
+| related     | message-id, references                  |
++-------------+-----------------------------------------+
 | <empty>     | to, cc, bcc, from, subject, body, embed |
 +-------------+-----------------------------------------+
 #+end_example

mu4e/mu4e-search.el

@@ -352,10 +352,38 @@ either `future' or `past'."
     (read-string prompt initial-input 'mu4e--search-hist)))
 
 (defconst mu4e--search-query-keywords
-  '("and" "or" "not"
-    "from:" "to:" "cc:" "bcc:" "contact:" "recip:" "date:" "subject:" "body:"
-    "list:" "maildir:" "flag:" "mime:" "file:" "prio:" "tag:" "msgid:"
-    "size:" "embed:"))
+  '(;; logical
+    "and"
+    "or"
+    "not"
+    ;; fields
+    "bcc:"
+    "body:"
+    "cc:"
+    "changed:"
+    "date:"
+    "embed:"
+    "file:"
+    "flag:"
+    "from:"
+    "lang:"
+    "maildir:"
+    "list:"
+    "msgid"
+    "mime:"
+    "path:"
+    "prio:"
+    "ref"
+    "size:"
+    "subject:"
+    "tags:"
+    "thread:"
+    "to:"
+    ;; combin fields
+    "recip:"
+    "contact:"
+    "related:")
+  "Mu4e query-keywords for completion.")
 
 (defun mu4e--search-completion-contacts-action (match _status)
   "Delete contact alias from contact autocompletion, leaving just email address.
@@ -378,7 +406,8 @@ status, STATUS."
     (list (match-beginning 1)
           (match-end 1)
           '("attach" "draft" "flagged" "list" "new" "passed" "replied"
-            "seen" "trashed" "unread" "encrypted" "signed" "personal")))
+            "seen" "trashed" "unread" "encrypted" "signed" "personal"
+            "calendar")))
    ((looking-back "maildir:\\([a-zA-Z0-9/.]*\\)" nil)
     (list (match-beginning 1)
           (match-end 1)