String '0x0001' cannot be converted to int

[haaspors]

I'm using get_define() and to_int() which gives this error.
Haven't looked deeply into meson regarding this, but should String.to_int() be able to parse hexadecimal and other number systems?

[jpakkane]

What is the specific use case for this?

[hadess]

Might be related:
https://gitlab.gnome.org/GNOME/gnome-control-center/issues/49

[neilmcgovern]

A specific use case in this context of the GNOME bug is the setting of permissions in config when building a project. For example, if you:
config.set("DEFAULT_PERMISSIONS", 0700,"Default permissions for new files")
then config.h will output:
#define DEFAULT PERMISSIONS 700

[nirbheek]

This issue is about str.to_int() knowing that "0x01" represents a hex in string form, and same for octal. The problem you're hitting is that the integer type in Meson does not support octal. We support hex (0xFF, etc), but not 0644, etc.

However, you do not really need this. As suggested on the GitLab issue, you can use strings.

[nirbheek]

... however if we don't support octal we should not silently drop the leading 0. We should error out or at least give a warning.

[s-bear]

Hello -- I just ran into a specific use case for this issue while porting some microcontroller firmware from Make to Meson.

Specifically, I need to use gcc/ld's option -Wl,--section-start=name=address to control code placement in the device's memory (to avoid conflict between application code & bootloader). Unfortunately, the address "must be a single hexadecimal integer" and "for compatibility with other linkers, you may omit the leading 0x usually associated with hexadecimal values" (https://www.man7.org/linux/man-pages/man1/ld.1.html).

I have complied with this by using a str in Meson to represent the address, but this has caused another issue down the line with srec_cat, which I am using to inject the CRC-16 of the binary into the compiled hex file. srec_cat of course needs to know where in the file to insert the CRC, which in my case is crc_address = app_address - 2. I tried the obvious thing:

app_address = '0x200'
crc_address = app_address.to_int() - 2

but of course this caused an error. My current workaround is to hardcode crc_address, but this is error-prone. I would much prefer if str.to_int() and/or int.to_string() supported hex numbers.

Cheers,
Sam

PS: Other than this issue, Meson has been a very nice change! The build file is half the length of the old Makefile and decidedly easier to understand :)

[eyalitki]

@jpakkane it seems that supporting this feature requires a simple modification in

meson/mesonbuild/interpreter/primitives/string.py

Line 132 in 39ebb85

def to_int_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> int:

This can be done using an attempt to detect the base by looking for "0x" prefix and "0" prefix before trying the naive based of 10.

Should I submit a PR for doing so?