Fail to set up AHB clock (for USB) in nightly

[hacknus]

I tried both USB-examples on my STM32F405; poll and interrupt and both work with rust stable (rustc 1.66.0 ) but hang with nightly (rustc 1.68.0-nightly).
By using the debugger, I notice that I get stuck in this line:

// Wait for AHB ready
while read_reg!(otg_global, regs.global(), GRSTCTL, AHBIDL) == 0 {}

line 365 in .cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/bus.rs

full output of the debugger:

synopsys_usb_otg::bus::{impl#2}::enable::{closure#0}<stm32f4xx_hal::otg_fs::USB> (cs=<optimized out>)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/bus.rs:365
365	            while read_reg!(otg_global, regs.global(), GRSTCTL, AHBIDL) == 0 {}
(gdb) 
halted: PC: 0x08002ace
halted: PC: 0x08002ac6
synopsys_usb_otg::ral::register::RWRegister<u32>::read<u32> (self=<optimized out>)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/ral/register.rs:23
23	        unsafe { ::core::ptr::read_volatile(self.register.get()) }
(gdb) step
0x08002ac6 in core::ptr::read_volatile<u32> (src=<optimized out>) at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/ptr/mod.rs:1521
1521	/rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/ptr/mod.rs: No such file or directory.
(gdb) step
halted: PC: 0x08002aca
synopsys_usb_otg::bus::{impl#2}::enable::{closure#0}<stm32f4xx_hal::otg_fs::USB> (cs=<optimized out>)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/bus.rs:365
365	            while read_reg!(otg_global, regs.global(), GRSTCTL, AHBIDL) == 0 {}
(gdb) 
halted: PC: 0x08002ace
halted: PC: 0x08002ac6

it seems in --release some stuff is optimized out, but it gets stuck at the same point in debug:

linuss-MacBook-Pro:stm32-usb-rust linus$ arm-none-eabi-gdb -q -ex "target remote :3333" target/thumbv7em-none-eabihf/debug/stm32-usb-rust
Reading symbols from target/thumbv7em-none-eabihf/debug/stm32-usb-rust...
Remote debugging using :3333
core::ptr::read_volatile<u32> (src=0x500000d8) at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/ptr/mod.rs:1523
1523	/rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/ptr/mod.rs: No such file or directory.
(gdb) step
halted: PC: 0x08013160
halted: PC: 0x08003590
halted: PC: 0x08003592
synopsys_usb_otg::bus::{impl#2}::enable::{closure#0}<stm32f4xx_hal::otg_fs::USB> (cs=0x2000971c)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/bus.rs:365
365	            while read_reg!(otg_global, regs.global(), GRSTCTL, AHBIDL) == 0 {}
(gdb) 
halted: PC: 0x08003594
halted: PC: 0x08003596
halted: PC: 0x0800359a
halted: PC: 0x08003580
halted: PC: 0x08003582
halted: PC: 0x08003584
365	            while read_reg!(otg_global, regs.global(), GRSTCTL, AHBIDL) == 0 {}
(gdb) 
synopsys_usb_otg::target::UsbRegisters::global (self=0x20009c38)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/target.rs:51
51	        unsafe { &*(self.0 as *const _) }
(gdb) 
halted: PC: 0x08003586
synopsys_usb_otg::bus::{impl#2}::enable::{closure#0}<stm32f4xx_hal::otg_fs::USB> (cs=0x2000971c)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/bus.rs:365
365	            while read_reg!(otg_global, regs.global(), GRSTCTL, AHBIDL) == 0 {}
(gdb) 
halted: PC: 0x08003588
halted: PC: 0x0800358a
halted: PC: 0x0800358c
synopsys_usb_otg::ral::register::RWRegister<u32>::read<u32> (self=0x500000d8)
    at /Users/linus/.cargo/registry/src/github.com-1ecc6299db9ec823/synopsys-usb-otg-0.3.1/src/ral/register.rs:23
23	        unsafe { ::core::ptr::read_volatile(self.register.get()) }
(gdb) 
halted: PC: 0x08013154
Note: automatically using hardware breakpoints for read-only addresses.
core::ptr::read_volatile<u32> (src=0x500000d8) at /rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/ptr/mod.rs:1521
1521	/rustc/659e169d37990b9c730a59a96081f2ef7afbe8f1/library/core/src/ptr/mod.rs: No such file or directory.

[burrbull]

https://github.com/stm32-rs/synopsys-usb-otg

[adamgreig]

Closing this issue in preference of stm32-rs/synopsys-usb-otg#33, thanks for reporting!