[bug] MesonToolchain ignores tools.build:defines ... and tc.preprocess_definitions quote problems

[paulharris]

Describe the bug

Windows, MSVC, conan 2.2.3

I'm building a project with MSVC and Debug mode.
I want to set _ITERATOR_DEBUG_LEVEL=0 across ALL dependencies. This is required for linking.

I added to the profile:

[conf]
tools.build:defines=["_ITERATOR_DEBUG_LEVEL=0"]

harfbuzz is a problem. It is a Meson recipe, and it appears Meson ignores tools.build:defines
I am not sure why, it has tc.preprocessor_definitions just like the CMakeToolchain, why would conan not pass these onto Meson as well?

Additionally, I tried to test by adjusting harfbuzz's recipe, by adding to def configure(self):
tc.preprocessor_definitions["_ITERATOR_DEBUG_LEVEL"] = 0

But Meson then builds with this command line (which fails with a cl.exe fatal error):

"cl" "-Isrc\libharfbuzz.a.p" "-Isrc" "-I..\src\src" "-I." "-I..\src" "-IM:/cocache4/cache/b/freet0508e9d7e6575/p/include" "-IM:/cocache4/cache/b/freet0508e9d7e6575/p/include/freetype2" "-IM:/cocache4/cache/b/libpn2b1716cb8fc8a/p/include" "-IM:/cocache4/cache/b/brotla8ae8b1cc3ea9/p/include" "-IM:/cocache4/cache/b/brotla8ae8b1cc3ea9/p/include/brotli" "-IM:/cocache4/cache/b/zlibaa051031a3f1a/p/include" "-IM:/cocache4/cache/b/bzip21d1b3a8fb9846/p/include" "-IM:/cocache4/cache/b/glib797de4fd80358/p/include" "-IM:/cocache4/cache/b/glib797de4fd80358/p/include/glib-2.0" "-IM:/cocache4/cache/b/glib797de4fd80358/p/lib/glib-2.0/include" "-IM:/cocache4/cache/b/pcre2002bf79de5d67/p/include" "-IM:/cocache4/cache/b/libgee81b73e14585e/p/include" "-IM:/cocache4/cache/b/libic07bd529a5ac88/p/include" "/MDd" "/nologo" "/showIncludes" "/utf-8" "/Zc:__cplusplus" "/W2" "/EHs-c-" "/std:c++20" "/Od" "/Zi" "/wd4244" "/utf-8" "-DHAVE_CONFIG_H" "-D_ITERATOR_DEBUG_LEVEL=\"0\"" "-DPCRE2_STATIC" "/Fdsrc\libharfbuzz.a.p\hb-ot-map.cc.pdb" /Fosrc/libharfbuzz.a.p/hb-ot-map.cc.obj "/c" ../src/src/hb-ot-map.cc

Note this command line parameter: "-D_ITERATOR_DEBUG_LEVEL=\"0\""
It should simply read: "-D_ITERATOR_DEBUG_LEVEL=0"

I can't even hack the recipe to get where I need to go ...

[paulharris]

It appears to work if I add to the profile:

tools.build:cflags=["-D_ITERATOR_DEBUG_LEVEL=0"]
tools.build:cxxflags=["-D_ITERATOR_DEBUG_LEVEL=0"]

Why aren't tools.build:defines supported for MesonToolchain?

[franramirez688]

Hi @paulharris

You're right, thanks a lot for reporting 👍 Working on fixing this.

[paulharris]

Please also see my comment in the PR re docs,
#16172 (comment)