meson/docs/markdown/snippets/per-machine-options.md

Specifying options per mer machine

Previously, no cross builds were controllable from the command line. Machine-specific options like the pkg-config path and compiler options only affected native targets, that is to say all targets in native builds, and native: true targets in cross builds. Now, prefix the option with build. to affect build machine targets, and leave it unprefixed to affect host machine targets.

For those trying to ensure native and cross builds to the same platform produced the same result, the old way was frustrating because very different invocations were needed to affect the same targets, if it was possible at all. Now, the same command line arguments affect the same targets everwhere --- Meson is closer to ignoring whether the "overall" build is native or cross, and just caring about whether individual targets are for the build or host machines.