Control: block -1 by 1029106 [ Nicolas CCed you only FYI. :) ]
Hi! On Fri, 2024-08-23 at 22:54:05 +0200, Andrea Pappacoda wrote: > Package: dpkg-dev > Version: 1.22.11 > Severity: normal > Hi! I've just noted a strange behaviour of buildflags.mk. In short, including > the file seems to remove some level of string quoting from preprocessor flags > defined with DEB_CPPFLAGS_MAINT_APPEND, almost as if the value was passed to a > shell one too many times. It is simpler to explain this with an example. > > Let's suppose the upstream software requires you to define a preprocessor > variable with a string value, like this one: […] > As you can see, the package builds and runs as expected, and the compiler is > invoked with -DFOO='"string_value"'. The issue presents when including > /usr/share/dpkg/buildflags.mk, just after the shebang line: […] > As you can see, in the second run the compiler is invoked with > -DFOO='string_value'. The double quotes get removed, even if surrounded with > single quotes; this of course leads to build failures. > > It is worth noting that the issue presents also when invoking "debian/rules > binary" directly, without delegating to dpkg-buildpackage. > > This seems to me like a bug in buildflags.mk, but I may be doing something > stupid I don't notice. I'm afraid, that while suboptimal, the behavior is currently what it is, and modifying it would break existing debian/rules files that expect the current behavior. :/ Also I'm not sure we could fix this easily with the current GNU make in Debian. I think the main roadblock is that GNU make does not pass exported make variables into $(shell) function invocations, which I think is what is probably causing the shell evaluation and mangling of these values. But the version supporting that, is not even in Debian: ,--- NEWS --- Version 4.4 (31 Oct 2022) […] * WARNING: Backward-incompatibility! Previously makefile variables marked as export were not exported to commands started by the $(shell ...) function. Now, all exported variables are exported to $(shell ...). If this leads to recursion during expansion, then for backward-compatibility the value from the original environment is used. To detect this change search for 'shell-export' in the .FEATURES variable. `--- I guess this could be considered as part of the work to reintroduce the performance optimizations that Nicolas worked on, or a later iteration on that once we have a fixed GNU make, where we could introduce this through a dpkg-build-api level for example, and tie that into requiring a fixed GNU make version. Thanks, Guillem
