rename "cid format --codec" to "cid format --mc"

CHANGELOG.md

@@ -54,7 +54,9 @@ Below is an outline of all that is in this release, so you get a sense of all th
 - `ipfs cid codecs --supported` can be passed to only show codecs supported in various go-ipfs commands.
 
 #### `ipfs cid format` command
-- CidV0 Now correctly requires the `dag-pb` codec, instead of the `protobuf` codec.
+- `--codec` was removed and replaced with `--mc` to ensure existing users are aware of the following changes:
+  - `--mc protobuf` now correctly points to code `0x50` (was `0x70`, which is `dab-pg`)
+  - `--mc cbor` now correctly points to code `0x51` (was `0x71`, which is `dag-cbor`)
 
 #### `Swarm` configuration
 - Daemon will refuse to start if long-deprecated RelayV1 config key `Swarm.EnableAutoRelay` or `Swarm.DisableRelay` is set to `true`.

core/commands/cid.go

@@ -35,7 +35,7 @@ var CidCmd = &cmds.Command{
 const (
 	cidFormatOptionName    = "f"
 	cidVerisonOptionName   = "v"
-	cidCodecOptionName     = "codec"
+	cidCodecOptionName     = "mc"
 	cidMultibaseOptionName = "b"
 )
 

test/sharness/t0290-cid.sh

@@ -284,13 +284,22 @@ test_expect_success "cid hashes --numeric" '
 
 test_expect_success "cid format -c raw" '
   echo $CIDb32raw > expected &&
-  ipfs cid format --codec raw -b base32 $CIDb32pb > actual &&
+  ipfs cid format --mc raw -b base32 $CIDb32pb > actual &&
   test_cmp actual expected
 '
 
 test_expect_success "cid format -c protobuf -v 0" '
   echo $CIDbase > expected &&
-  ipfs cid format --codec dag-pb -v 0 $CIDb32raw > actual &&
+  ipfs cid format --mc dag-pb -v 0 $CIDb32raw > actual &&
+  test_cmp actual expected
+'
+
+# this was an old flag that we removed, explicitly to force an error
+# so the user would read about the new multicodec names introduced
+# by https://github.com/ipfs/go-cid/commit/b2064d74a8b098193b316689a715cdf4e4934805
+test_expect_success "cid format --codec fails" '
+  echo "Error: unknown option \"codec\"" > expected &&
+  test_expect_code 1 ipfs cid format --codec protobuf 2> actual &&
   test_cmp actual expected
 '