compilers/detect: Update the build machine information for ASM

The ASM compilers need the machine information to be up to date before
they're initialized. Which is a reasonable thing as they use the c
linker information. This was done by creating a unique MachineInfo. That
code was dropped when the compilers were refactored to use the
Environment instead of a separate MachineInfo.

This patch is honestly not what I'd hope for, but it's minimal for
application to the stable branch. This should be followed up by more
cleanups, but that will involve more work.

Fixes: #15361

Author: dcbaker

mesonbuild/compilers/detect.py

@@ -1328,8 +1328,9 @@ def detect_nasm_compiler(env: 'Environment', for_machine: MachineChoice) -> Comp
     compilers, _ = _get_compilers(env, 'nasm', for_machine, allow_build_machine=True)
 
     # We need a C compiler to properly detect the machine info and linker
-    
     cc = detect_c_compiler(env, for_machine)
+    if not (env.build_machines_are_exact or env.is_cross_build(for_machine)):
+        env.update_build_machine({'c': cc})
 
     popen_exceptions: T.Dict[str, Exception] = {}
     for comp in compilers:
@@ -1369,10 +1370,10 @@ def detect_nasm_compiler(env: 'Environment', for_machine: MachineChoice) -> Comp
 def detect_masm_compiler(env: 'Environment', for_machine: MachineChoice) -> Compiler:
     # We need a C compiler to properly detect the machine info and linker
     cc = detect_c_compiler(env, for_machine)
-    if not env.is_cross_build(for_machine):
-        info = detect_machine_info({'c': cc})
-    else:
-        info = env.machines[for_machine]
+    if not (env.build_machines_are_exact or env.is_cross_build(for_machine)):
+        env.update_build_machine({'c': cc})
+
+    info = env.machines[for_machine]
 
     from .asm import MasmCompiler, MasmARMCompiler
     comp_class: T.Type[ASMCompiler]
@@ -1412,6 +1413,8 @@ def detect_linearasm_compiler(env: Environment, for_machine: MachineChoice) -> C
     comp_class: T.Type[ASMCompiler] = TILinearAsmCompiler
     arg = '-h'
     cc = detect_c_compiler(env, for_machine)
+    if not (env.build_machines_are_exact or env.is_cross_build(for_machine)):
+        env.update_build_machine({'c': cc})
 
     popen_exceptions: T.Dict[str, Exception] = {}
     try: