From 4fe0fb3748914fd7462998f7c85b2015bfe1dcbd Mon Sep 17 00:00:00 2001
From: Tobias Decking <Tobias.Decking@gmail.com>
Date: Thu, 3 Sep 2026 22:04:22 +0200
Subject: [PATCH 1/2] Add a test for the `defmt` feature

---
 Cargo.lock     | 552 ++++++++++++++++++++++++++++++++++++++++++++++++-
 Cargo.toml     |   6 +
 tests/defmt.rs | 102 +++++++++
 3 files changed, 659 insertions(+), 1 deletion(-)
 create mode 100644 tests/defmt.rs

diff --git a/Cargo.lock b/Cargo.lock
index 08d6e29..c663b10 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -20,6 +20,26 @@ dependencies = [
  "cc",
 ]
 
+[[package]]
+name = "alterable_logger"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a1f292171444480aedbc1b7d1a11192d1b6e48f26154cf4635481c58b9b419f"
+dependencies = [
+ "arc-swap",
+ "log",
+ "once_cell",
+]
+
+[[package]]
+name = "android_system_properties"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae221649c9976a6f6c56ae1facf410f3ddb33cc661c4b7b61020a912d4237fbc"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "anes"
 version = "0.1.6"
@@ -32,12 +52,27 @@ version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "940b3a0ca603d1eade50a4846a2afffd5ef57a9feac2c0e2ec2e14f9ead76000"
 
+[[package]]
+name = "anyhow"
+version = "1.0.104"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
+
 [[package]]
 name = "arbitrary"
 version = "1.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c3d036a3c4ab069c7b410a2ce876bd74808d2d0888a82667669f8e783a898bf1"
 
+[[package]]
+name = "arc-swap"
+version = "1.9.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c049c0be4daef0b145cb3555416b3b8ef5b7888a38aea1a3a155801fe7b0810b"
+dependencies = [
+ "rustversion",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.5.1"
@@ -79,6 +114,12 @@ version = "3.20.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72f5acc6cb2ba439de613abc23857ec3d78374d8ed5ac84e9d11336e87da8649"
 
+[[package]]
+name = "byteorder"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
 [[package]]
 name = "bytes"
 version = "1.12.1"
@@ -91,6 +132,23 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
 
+[[package]]
+name = "cbor-edn"
+version = "0.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a9b43829b1f353168aa8593c2e4ef6e71a81d6749fe09edfc33849f890c69278"
+dependencies = [
+ "chrono",
+ "data-encoding",
+ "data-encoding-macro",
+ "encoding_rs",
+ "hex",
+ "hexfloat2",
+ "num-bigint",
+ "num-traits",
+ "peg",
+]
+
 [[package]]
 name = "cc"
 version = "1.4.4"
@@ -113,6 +171,19 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f079e83a288787bcd14a6aea84cee5c87a67c5a3e660c30f557a3d24761b3527"
 
+[[package]]
+name = "chrono"
+version = "0.4.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1aa79e62e7697b8e29b513a68abacf485adcd1fe8284a4316c5ae868e6633327"
+dependencies = [
+ "iana-time-zone",
+ "js-sys",
+ "num-traits",
+ "wasm-bindgen",
+ "windows-link",
+]
+
 [[package]]
 name = "ciborium"
 version = "0.2.2"
@@ -165,6 +236,16 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c8d4a3bb8b1e0c1050499d1815f5ab16d04f0959b233085fb31653fbfc9d98f9"
 
+[[package]]
+name = "colored"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "117725a109d387c937a1533ce01b450cbde6b88abceea8473c4d7a85853cda3c"
+dependencies = [
+ "lazy_static",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "const_panic"
 version = "0.2.17"
@@ -174,6 +255,21 @@ dependencies = [
  "typewit",
 ]
 
+[[package]]
+name = "core-foundation-sys"
+version = "0.8.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
+
+[[package]]
+name = "crc32fast"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8498c871161e1742aaa9d52551b2d6ebdd4c3d45a3be423e3728f33b955be550"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "criterion"
 version = "0.8.2"
@@ -240,6 +336,32 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
+[[package]]
+name = "data-encoding"
+version = "2.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4583a4551df46e2792f82ceeac45e850d2e2d5debba0b91f102385cda5b11f06"
+
+[[package]]
+name = "data-encoding-macro"
+version = "0.1.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c6a127ecbb3c4632e1525380e04c0c3fcf8dcb44d32a79ea290d8a36906edcd8"
+dependencies = [
+ "data-encoding",
+ "data-encoding-macro-internal",
+]
+
+[[package]]
+name = "data-encoding-macro-internal"
+version = "0.1.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c54e03a951783e8b327515db3f2a2fd0e3bed362a96b066f341ce66ed49b4ead"
+dependencies = [
+ "data-encoding",
+ "syn 3.0.4",
+]
+
 [[package]]
 name = "defmt"
 version = "1.1.1"
@@ -250,6 +372,41 @@ dependencies = [
  "defmt-macros",
 ]
 
+[[package]]
+name = "defmt-decoder"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e0427c033f70d46bffe9fc575aa27cb43b1a73d6a0bbe25710c7308809196d2"
+dependencies = [
+ "alterable_logger",
+ "anyhow",
+ "byteorder",
+ "cbor-edn",
+ "colored",
+ "defmt-json-schema",
+ "defmt-parser",
+ "dissimilar",
+ "gimli",
+ "log",
+ "nom",
+ "object 0.36.7",
+ "regex",
+ "ryu",
+ "serde",
+ "serde_json",
+ "time",
+]
+
+[[package]]
+name = "defmt-json-schema"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96b04d228e57a61cf385d86bc8980bb41b47c6fc0eace90592668df97b2dad6a"
+dependencies = [
+ "log",
+ "serde",
+]
+
 [[package]]
 name = "defmt-macros"
 version = "1.1.1"
@@ -271,6 +428,36 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "defmt2log"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e5be3b401a817cfe24125124eefeb69c5f9c597c5a2def0de6d81e836578a67"
+dependencies = [
+ "defmt",
+ "defmt-decoder",
+ "defmt-parser",
+ "findshlibs",
+ "log",
+ "object 0.39.1",
+ "serde_json",
+]
+
+[[package]]
+name = "deranged"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7cd812cc2bc1d69d4764bd80df88b4317eaef9e773c75226407d9bc0876b211c"
+dependencies = [
+ "powerfmt",
+]
+
+[[package]]
+name = "dissimilar"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aeda16ab4059c5fd2a83f2b9c9e9c981327b18aa8e3b313f7e6563799d4f093e"
+
 [[package]]
 name = "either"
 version = "1.18.0"
@@ -308,18 +495,51 @@ dependencies = [
  "syn 2.0.119",
 ]
 
+[[package]]
+name = "encoding_rs"
+version = "0.8.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75030f3c4f45dafd7586dd6780965a8c7e8e285a5ecb86713e63a79c5b2766f3"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
+[[package]]
+name = "fallible-iterator"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2acce4a10f12dc2fb14a218589d4f1f62ef011b2d0cc4b3cb1bba8e94da14649"
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d45db016d36b838f563236e9193d0ee6ce38f3f68b6c94e914b4929c96bbb890"
 
+[[package]]
+name = "findshlibs"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40b9e59cd0f7e0806cca4be089683ecb6434e602038df21fe6bf6711b2f07f64"
+dependencies = [
+ "cc",
+ "lazy_static",
+ "libc",
+ "winapi",
+]
+
+[[package]]
+name = "foldhash"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"
+
 [[package]]
 name = "futures-core"
 version = "0.3.34"
@@ -344,6 +564,16 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "gimli"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40ecd4077b5ae9fd2e9e169b102c6c330d0605168eb0e8bf79952b256dbefffd"
+dependencies = [
+ "fallible-iterator",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "half"
 version = "2.7.1"
@@ -360,6 +590,45 @@ name = "hashbrown"
 version = "0.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a"
+dependencies = [
+ "foldhash",
+]
+
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
+[[package]]
+name = "hexfloat2"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "befe65164a090041cdf6e0d21a0ec3198d856fbfe2b76e324a073e790bb49f8c"
+
+[[package]]
+name = "iana-time-zone"
+version = "0.1.65"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e31bc9ad994ba00e440a8aa5c9ef0ec67d5cb5e5cb0cc7f8b744a35b389cc470"
+dependencies = [
+ "android_system_properties",
+ "core-foundation-sys",
+ "iana-time-zone-haiku",
+ "js-sys",
+ "log",
+ "wasm-bindgen",
+ "windows-core",
+]
+
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
+dependencies = [
+ "cc",
+]
 
 [[package]]
 name = "indexmap"
@@ -397,12 +666,27 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.189"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3eaf3ede3fee6db1a4c2ee091bf8a8b4dccdc6d17f656fb07896ee72867612f2"
 
+[[package]]
+name = "log"
+version = "0.4.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9f8bd3e56ce4dfc153cf470fffbfa98c7620958b312ca5c3a4b8d5181fd13c6"
+dependencies = [
+ "serde_core",
+]
+
 [[package]]
 name = "malloc_size_of"
 version = "0.1.1"
@@ -415,6 +699,47 @@ version = "2.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]
+
+[[package]]
+name = "num-bigint"
+version = "0.4.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c89e69e7e0f03bea5ef08013795c25018e101932225a656383bd384495ecc367"
+dependencies = [
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-conv"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51d515d32fb182ee37cda2ccdcb92950d6a3c2893aa280e540671c2cd0f3b1d9"
+
+[[package]]
+name = "num-integer"
+version = "0.1.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ce2d95d4b3734dc35aa2f45e1aa22cd416814592a4f9d9205e11affd5b8e10b"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -424,6 +749,27 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "object"
+version = "0.36.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62948e14d923ea95ea2c7c86c71013138b66525b86bdc08d2dcc262bdb497b87"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "object"
+version = "0.39.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e5a6c098c7a3b6547378093f5cc30bc54fd361ce711e05293a5cc589562739b"
+dependencies = [
+ "crc32fast",
+ "hashbrown",
+ "indexmap",
+ "memchr",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.21.4"
@@ -446,6 +792,33 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "peg"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0aad070be5b63aa72103f2fcdd70a83adbd5e90112ce5b574171ff1c65501773"
+dependencies = [
+ "peg-macros",
+ "peg-runtime",
+]
+
+[[package]]
+name = "peg-macros"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddd8ef6825cae95355031ae26a99b616a2a21f22ba2de0197c43dfb05acbe7ee"
+dependencies = [
+ "peg-runtime",
+ "proc-macro2",
+ "quote",
+]
+
+[[package]]
+name = "peg-runtime"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7011d97b484a5ebdc4b1fdb3b12d5e4bbbea56e9d22b688f2e79e04b65a7d8a6"
+
 [[package]]
 name = "pin-project-lite"
 version = "0.2.17"
@@ -480,6 +853,12 @@ dependencies = [
  "plotters-backend",
 ]
 
+[[package]]
+name = "powerfmt"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "439ee305def115ba05938db6eb1644ff94165c5ab5e9420d1c1bcedbba909391"
+
 [[package]]
 name = "proc-macro-crate"
 version = "3.5.0"
@@ -562,6 +941,12 @@ version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf54715a573b99ac80df0bc206da022bcd442c974952c7b9720069370852e21f"
 
+[[package]]
+name = "ryu"
+version = "1.0.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9774ba4a74de5f7b1c1451ed6cd5285a32eddb5cccb8cc655a4e50009e06477f"
+
 [[package]]
 name = "same-file"
 version = "1.0.6"
@@ -644,13 +1029,21 @@ dependencies = [
  "bytes",
  "criterion",
  "defmt",
+ "defmt2log",
  "encase",
+ "log",
  "malloc_size_of",
  "rayon",
  "serde_core",
  "serde_test",
 ]
 
+[[package]]
+name = "stable_deref_trait"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
+
 [[package]]
 name = "syn"
 version = "2.0.119"
@@ -693,6 +1086,37 @@ dependencies = [
  "syn 3.0.4",
 ]
 
+[[package]]
+name = "time"
+version = "0.3.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9e442fc33d7fdb45aa9bfeb312c095964abdf596f7567261062b2a7107aaabd"
+dependencies = [
+ "deranged",
+ "itoa",
+ "num-conv",
+ "powerfmt",
+ "serde_core",
+ "time-core",
+ "time-macros",
+]
+
+[[package]]
+name = "time-core"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b36ee98fd31ec7426d599183e8fe26932a8dc1fb76ddb6214d05493377d34ca"
+
+[[package]]
+name = "time-macros"
+version = "0.2.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71e552d1249bf61ac2a52db88179fd0673def1e1ad8243a00d9ec9ed71fee3dd"
+dependencies = [
+ "num-conv",
+ "time-core",
+]
+
 [[package]]
 name = "tinytemplate"
 version = "1.2.1"
@@ -832,7 +1256,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -841,12 +1265,74 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
+[[package]]
+name = "windows-core"
+version = "0.62.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8e83a14d34d0623b51dce9581199302a221863196a1dde71a7663a4c2be9deb"
+dependencies = [
+ "windows-implement",
+ "windows-interface",
+ "windows-link",
+ "windows-result",
+ "windows-strings",
+]
+
+[[package]]
+name = "windows-implement"
+version = "0.60.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "053e2e040ab57b9dc951b72c264860db7eb3b0200ba345b4e4c3b14f67855ddf"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
+
+[[package]]
+name = "windows-interface"
+version = "0.59.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f316c4a2570ba26bbec722032c4099d8c8bc095efccdc15688708623367e358"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.119",
+]
+
 [[package]]
 name = "windows-link"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
 
+[[package]]
+name = "windows-result"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7781fa89eaf60850ac3d2da7af8e5242a5ea78d1a11c49bf2910bb5a73853eb5"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-strings"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7837d08f69c77cf6b07689544538e017c1bfcf57e34b4c0ff58e6c2cd3b37091"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.61.2"
@@ -856,6 +1342,70 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
 [[package]]
 name = "winnow"
 version = "1.0.4"
diff --git a/Cargo.toml b/Cargo.toml
index 687c3ae..a194b01 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,6 +38,8 @@ malloc_size_of = { version = "0.1", optional = true, default-features = false }
 [dev-dependencies]
 serde_test = "1.0"
 criterion = "0.8"
+defmt2log = "0.2"
+log = "0.4"
 
 [[test]]
 name = "arbitrary"
@@ -51,6 +53,10 @@ required-features = ["borsh"]
 name = "bytes"
 required-features = ["bytes"]
 
+[[test]]
+name = "defmt"
+required-features = ["defmt"]
+
 [[test]]
 name = "encase"
 required-features = ["encase"]
diff --git a/tests/defmt.rs b/tests/defmt.rs
new file mode 100644
index 0000000..0ac1c56
--- /dev/null
+++ b/tests/defmt.rs
@@ -0,0 +1,102 @@
+// By default, `defmt` will log error-level messages and no other level.
+// Wether a message at a given level is emitted is decided at compile time,
+// so this level is chosen to avoid making this test special inside CI.
+use {
+    defmt::error,
+    defmt2log::init_from_current_exe,
+    log::{
+        Level,
+        LevelFilter,
+        Metadata,
+        Record
+    },
+    smallvec::SmallVec,
+    std::sync::Mutex
+};
+
+// Logging infrastructure taken from the `defmt2log` crate test suite.
+
+struct TestLogger {
+    records: Mutex<SmallVec<(Level, String), 16>>
+}
+
+impl TestLogger {
+    fn install(&'static self) {
+        if log::set_logger(self).is_ok() {
+            log::set_max_level(LevelFilter::Trace);
+        }
+        self.records.lock().unwrap().clear();
+    }
+
+    fn take(&self) -> Vec<(Level, String)> {
+        self.records.lock().unwrap().drain(..).collect()
+    }
+}
+
+impl log::Log for TestLogger {
+    fn enabled(&self, _metadata: &Metadata<'_>) -> bool {
+        true
+    }
+
+    fn log(&self, record: &Record<'_>) {
+        self.records
+            .lock()
+            .unwrap()
+            .push((record.level(), record.args().to_string()));
+    }
+
+    fn flush(&self) {}
+}
+
+static LOGGER: TestLogger = TestLogger {
+    records: Mutex::new(SmallVec::new())
+};
+
+#[test]
+#[cfg_attr(miri, ignore = "isolated environment makes execution impossible")]
+#[cfg_attr(target_os = "windows", ignore = "windows is not supported by `defmt`")]
+fn test_defmt() {
+    init_from_current_exe();
+    LOGGER.install();
+
+    let mut expected = SmallVec::<&'static str, 16>::new();
+
+    // Vectors storing bytes.
+
+    // Empty vector.
+    let s: SmallVec<u8, 2> = SmallVec::new();
+    error!("{=[?]}", s);
+    expected.push("[]");
+
+    // Vector with inline storage.
+    let s: SmallVec<u8, 2> = SmallVec::from([1, 4, 9, 16]);
+    error!("{=[?]}", s);
+    expected.push("[1, 4, 9, 16]");
+
+    // Vector with heap storage.
+    let s: SmallVec<u8, 8> = SmallVec::from([2, 5, 10, 17]);
+    error!("{=[?]}", s);
+    expected.push("[2, 5, 10, 17]");
+
+    // Vectors storing string slices.
+
+    // Empty vector.
+    let s: SmallVec<&'static str, 2> = SmallVec::new();
+    error!("{=[?]}", s);
+    expected.push("[]");
+
+    // Vector with inline storage.
+    let s: SmallVec<&'static str, 2> = SmallVec::from(["a", "b", "c", "d"]);
+    error!("{=[?]}", s);
+    expected.push("[a, b, c, d]");
+
+    // Vector with heap storage.
+    let s: SmallVec<&'static str, 8> = SmallVec::from(["e", "f", "g", "h"]);
+    error!("{=[?]}", s);
+    expected.push("[e, f, g, h]");
+
+    let records = LOGGER.take();
+    for (actual, expected) in records.into_iter().map(|x| x.1).zip(expected.into_iter()) {
+        assert_eq!(expected, actual);
+    }
+}

From aac6d1d7758c8fd0de6a6b90416976e7f63ec88e Mon Sep 17 00:00:00 2001
From: Tobias Decking <Tobias.Decking@gmail.com>
Date: Fri, 4 Sep 2026 16:41:24 +0200
Subject: [PATCH 2/2] experiment: try to disable the test for MSRV

---
 .github/workflows/rust.yml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 6f8af7f..122af5d 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -29,6 +29,7 @@ jobs:
             nightly: true
           - name: MSRV
             toolchain: "1.86.0"
+            skip: --skip defmt
           - name: no_std
             toolchain: stable
             target: thumbv7m-none-eabi
@@ -55,7 +56,9 @@ jobs:
 
       - name: Run tests
         if: ${{ !matrix.no_std }}
-        run: cargo test --verbose
+        # The `defmt` test requires a newer Rust version, so skip the test
+        # for the MSRV.
+        run: cargo test --verbose -- ${{ matrix.skip }}
 
       - name: Cargo test all features
         if: matrix.nightly