panicked with `test.h`, but ok with `__binding.i`

Input C/C++ Header

#include <stdint.h>
const uint32_t test = 123;

Bindgen Invocation

$ bindgen test.h

Actual Results

test.h:5:7: error: unknown type name 'uint32_t'
test.h:5:7: error: unknown type name 'uint32_t', err: true
thread 'main' panicked at 'Unable to generate bindings: ()', libcore/result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.

Expected Results

generating __binding.i file instead it works:

First generate __binding.i file using -dump-preprocessed-input

$ bindgen --dump-preprocessed-input test.h
test.h:2:7: error: unknown type name 'uint32_t'
test.h:2:7: error: unknown type name 'uint32_t', err: true
thread 'main' panicked at 'Unable to generate bindings: ()', libcore/result.rs:1009:5

and than:

$ bindgen __bindgen.i
warning: argument unused during compilation: '-isystem /usr/local/include' [-Wunused-command-line-argument], err: false
warning: argument unused during compilation: '-isystem /usr/local/Cellar/llvm@3.7/3.7.1/lib/llvm-3.7/bin/../lib/clang/3.7.1/include' [-Wunused-command-line-argument], err: false
warning: argument unused during compilation: '-isystem /System/Library/Frameworks' [-Wunused-command-line-argument], err: false
warning: argument unused during compilation: '-isystem /Library/Frameworks' [-Wunused-command-line-argument], err: false
/* automatically generated by rust-bindgen */

pub type int_least64_t = i64;
pub type uint_least64_t = u64;
pub type int_fast64_t = i64;
pub type uint_fast64_t = u64;
pub type int_least32_t = i32;
pub type uint_least32_t = u32;
pub type int_fast32_t = i32;
pub type uint_fast32_t = u32;
pub type int_least16_t = i16;
pub type uint_least16_t = u16;
pub type int_fast16_t = i16;
pub type uint_fast16_t = u16;
pub type int_least8_t = i8;
pub type uint_least8_t = u8;
pub type int_fast8_t = i8;
pub type uint_fast8_t = u8;
pub type intmax_t = ::std::os::raw::c_long;
pub type uintmax_t = ::std::os::raw::c_ulong;
pub const test: u32 = 123;

thanks

$ bindgen --version
bindgen 0.45.0
$ uname -a
Darwin MacBook-Pro.local 18.2.0 Darwin Kernel Version 18.2.0: Fri Oct  5 19:41:49 PDT 2018; root:xnu-4903.221.2~2/RELEASE_X86_64 x86_64

Reproduce the report with test.h and bindgen 0.45.0, then compare direct processing with the --dump-preprocessed-input flow. Trace how uint32_t from <stdint.h> is handled before the panic; done means bindgen processes test.h without unknown-type errors or a panic and generates the expected u32 constant.