Added a macOS-only Meson configure-time guard that checks for the exact mismatch you hit: -arch x86_64 in build flags while pkg-config resolves GLib from /opt/homebrew (ARM Homebrew). This now fails early with a clear actionable error instead of letting the build continue to a long linker failure.

The new error message explicitly tells users to choose one consistent setup: native arm64 with /opt/homebrew, or Rosetta/x86_64 with an x86_64 dependency stack (typically /usr/local).

meson.build

@@ -35,6 +35,20 @@ else
                           required: get_option('tls'))
 endif
 
+if host_machine.system() == 'darwin'
+  cflags_env = run_command('sh', '-c', 'printf %s "$CFLAGS"', check: false).stdout().strip()
+  ldflags_env = run_command('sh', '-c', 'printf %s "$LDFLAGS"', check: false).stdout().strip()
+  pkgconfig_libs = run_command('pkg-config', '--libs', 'glib-2.0', check: false).stdout()
+
+  targeting_x86_64 = cflags_env.contains('-arch x86_64') or ldflags_env.contains('-arch x86_64')
+  using_arm_homebrew = pkgconfig_libs.contains('/opt/homebrew/')
+
+  if targeting_x86_64 and using_arm_homebrew
+    error('Detected x86_64 build flags (-arch x86_64) while pkg-config resolves glib from /opt/homebrew (arm64). ' +
+          'Use arm64 build flags with /opt/homebrew, or run an x86_64/Rosetta environment with an x86_64 dependency stack (typically /usr/local).')
+  endif
+endif
+
 config_h = configuration_data()
 config_h.set_quoted('PACKAGE_VERSION', meson.project_version())
 config_h.set_quoted('PACKAGE_NAME', meson.project_name())

osx/DEBUGGING.md

@@ -130,6 +130,48 @@ meson compile -C build-macos-intel
 
 If your dependency stack supports it, build universal (`arm64` + `x86_64`) and verify with `lipo -info`.
 
+### Linker says `found architecture 'arm64', required architecture 'x86_64'`
+
+If you see warnings like this during `meson compile`:
+
+```text
+ld: warning: ignoring file '/opt/homebrew/.../libgio-2.0.dylib': found architecture 'arm64', required architecture 'x86_64'
+Undefined symbols for architecture x86_64: ...
+```
+
+your compile target architecture and dependency architecture do not match.
+
+On Apple Silicon, this usually means you are trying to build `x86_64` while linking against ARM Homebrew libraries from `/opt/homebrew`.
+
+Quick checks:
+
+```bash
+echo "$CFLAGS" "$LDFLAGS"
+pkg-config --libs glib-2.0
+lipo -info "$(brew --prefix glib)/lib/libglib-2.0.dylib"
+```
+
+Use one of these consistent setups:
+
+- Native Apple Silicon build (`arm64`) with `/opt/homebrew` dependencies.
+- Intel build (`x86_64`) with an x86_64 dependency stack (typically Homebrew under `/usr/local` run under Rosetta).
+
+Example x86_64 setup on Apple Silicon:
+
+```bash
+# Open a Rosetta shell first (or prefix commands with `arch -x86_64`)
+arch -x86_64 /bin/bash -lc '
+  export PATH="/usr/local/bin:$PATH"
+  export PKG_CONFIG_PATH="/usr/local/lib/pkgconfig:/usr/local/share/pkgconfig"
+  export CFLAGS="-arch x86_64"
+  export LDFLAGS="-arch x86_64"
+  meson setup build-macos-x86_64 --prefix="/usr/local"
+  meson compile -C build-macos-x86_64
+'
+```
+
+If you do not specifically need Intel compatibility, remove any forced `-arch x86_64` flags and build native `arm64`.
+
 Example with this repo's scripts:
 
 ```bash