Bump cexpr to 0.5
diff --git a/.github/workflows/bindgen.yml b/.github/workflows/bindgen.yml
index 91efe98..7080352 100644
--- a/.github/workflows/bindgen.yml
+++ b/.github/workflows/bindgen.yml
@@ -42,11 +42,11 @@
           profile: minimal
           # MSRV below is documented in README.md, please update that if you
           # change this.
-          toolchain: 1.40.0
+          toolchain: 1.44.0
           override: true
 
       - name: Build with msrv
-        run: rm Cargo.lock && cargo +1.40.0 build --lib
+        run: rm Cargo.lock && cargo +1.44.0 build --lib
 
   quickchecking:
     runs-on: ubuntu-latest
diff --git a/Cargo.lock b/Cargo.lock
index 443201e..934dfe4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -61,10 +61,22 @@
 checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
 [[package]]
-name = "cexpr"
-version = "0.4.0"
+name = "bitvec"
+version = "0.19.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f4aedb84272dbe89af497cf81375129abda4fc0a9e7c5d317498c15cc30c0d27"
+checksum = "8942c8d352ae1838c9dda0b0ca2ab657696ef2232a20147cf1b30ae1a9cb4321"
+dependencies = [
+ "funty",
+ "radium",
+ "tap",
+ "wyz",
+]
+
+[[package]]
+name = "cexpr"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db507a7679252d2276ed0dd8113c6875ec56d3089f9225b2b42c30cc1f8e5c89"
 dependencies = [
  "nom",
 ]
@@ -127,6 +139,12 @@
 ]
 
 [[package]]
+name = "funty"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fed34cd105917e91daa4da6b3728c47b068749d6a62c59811f06ed2ac71d9da7"
+
+[[package]]
 name = "getrandom"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -203,10 +221,12 @@
 
 [[package]]
 name = "nom"
-version = "5.1.2"
+version = "6.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ffb4262d26ed83a1c0a33a38fe2bb15797329c85770da05e6b828ddb782627af"
+checksum = "9c5c51b9083a3c620fa67a2a635d1ce7d95b897e957d6b28ff9a5da960a103a6"
 dependencies = [
+ "bitvec",
+ "funty",
  "memchr",
  "version_check",
 ]
@@ -242,6 +262,12 @@
 ]
 
 [[package]]
+name = "radium"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "941ba9d78d8e2f7ce474c015eea4d9c6d25b6a3327f9832ee29a4de27f91bbb8"
+
+[[package]]
 name = "rand"
 version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -336,6 +362,12 @@
 checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 
 [[package]]
+name = "tap"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "55937e1799185b12863d447f42597ed69d9928686b8d88a1df17376a097d8369"
+
+[[package]]
 name = "tempfile"
 version = "3.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -445,3 +477,9 @@
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
+[[package]]
+name = "wyz"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85e60b0d1b5f99db2556934e21937020776a5d31520bf169e851ac44e6420214"
diff --git a/Cargo.toml b/Cargo.toml
index 6140407..b276eab 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,7 +47,7 @@
 
 [dependencies]
 bitflags = "1.0.3"
-cexpr = "0.4"
+cexpr = "0.5"
 # This kinda sucks: https://github.com/rust-lang/cargo/issues/1982
 clap = { version = "2", optional = true }
 clang-sys = { version = "1", features = ["clang_6_0"] }
@@ -59,8 +59,6 @@
 which = { version = "3.0", optional = true, default-features = false }
 shlex = "1"
 rustc-hash = "1.0.1"
-# New validation in 0.3.6 breaks bindgen-integration:
-# https://github.com/alexcrichton/proc-macro2/commit/489c642.
 proc-macro2 = { version = "1", default-features = false }
 
 [dependencies.env_logger]
diff --git a/README.md b/README.md
index 60e064f..00f66eb 100644
--- a/README.md
+++ b/README.md
@@ -39,7 +39,7 @@
 
 ## MSRV
 
-The minimum supported Rust version is **1.40**.
+The minimum supported Rust version is **1.44**.
 
 No MSRV bump policy has been established yet, so MSRV may increase in any release.