more push-spec restrictions (#450)

git-refspec/src/parse.rs

@@ -113,7 +113,7 @@ pub(crate) mod function {
                 *spec = "HEAD".into();
             }
         }
-        let (src, src_had_pattern) = validated(src, operation == Operation::Push)?;
+        let (src, src_had_pattern) = validated(src, operation == Operation::Push && dst.is_some())?;
         let (dst, dst_had_pattern) = validated(dst, false)?;
         if !dst_had_pattern && looks_like_object_hash(dst.unwrap_or_default()) {
             return Err(Error::InvalidFetchDestination);

git-refspec/tests/fixtures/make_baseline.sh

@@ -40,6 +40,10 @@ baseline push '^'
 
 baseline fetch '^refs/heads/qa/*/*'
 baseline push '^refs/heads/qa/*/*'
+baseline push 'main~1'
+baseline fetch 'main~1'
+baseline push 'main~1:other~1'
+baseline push ':main~1'
 
 baseline push 'refs/heads/*:refs/remotes/frotz'
 baseline push 'refs/heads:refs/remotes/frotz/*'

git-refspec/tests/parse/push.rs

@@ -11,6 +11,42 @@ fn negative_unsupported() {
     }
 }
 
+#[test]
+fn revspecs_with_ref_name_destination() {
+    assert_parse(
+        "main~1:b",
+        Instruction::Push(Push::Matching {
+            src: b("main~1"),
+            dst: b("b"),
+            allow_non_fast_forward: false,
+        }),
+    );
+    assert_parse(
+        "+main~1:b",
+        Instruction::Push(Push::Matching {
+            src: b("main~1"),
+            dst: b("b"),
+            allow_non_fast_forward: true,
+        }),
+    );
+}
+
+#[test]
+fn destinations_must_be_ref_names() {
+    assert!(matches!(
+        try_parse("a~1:b~1", Operation::Push).unwrap_err(),
+        Error::ReferenceName(_)
+    ));
+}
+
+#[test]
+fn single_refs_must_be_refnames() {
+    assert!(matches!(
+        try_parse("a~1", Operation::Push).unwrap_err(),
+        Error::ReferenceName(_)
+    ));
+}
+
 #[test]
 fn ampersand_is_resolved_to_head() {
     assert_parse(