internal/rosa/meson: support cross-compilation

Meson does not want to play nice and accept arguments or environment
variables for cross-compiling configuration, so a so-called mfile had
to be generated and placed here.

Signed-off-by: Ophestra <cat@gensokyo.uk>

7 files changed, 77 insertions, 16 deletions

diff --git a/internal/rosa/cmake.go b/internal/rosa/cmake.go
index c037a239..8cfbf00c 100644
--- a/internal/rosa/cmake.go
+++ b/internal/rosa/cmake.go
@@ -35,7 +35,7 @@ type CMakeHelper struct {
 var _ Helper = new(CMakeHelper)
 
 // tools returns the cmake handle alongside either ninja or make.
-func (attr *CMakeHelper) tools() P {
+func (attr *CMakeHelper) tools(Toolchain) P {
 	if attr != nil && attr.Make {
 		return P{_cmake, _make}
 	}
diff --git a/internal/rosa/make.go b/internal/rosa/make.go
index e0b9094f..c6a1d2fd 100644
--- a/internal/rosa/make.go
+++ b/internal/rosa/make.go
@@ -61,7 +61,7 @@ type MakeHelper struct {
 var _ Helper = new(MakeHelper)
 
 // tools returns make and other optional dependencies.
-func (attr *MakeHelper) tools() P {
+func (attr *MakeHelper) tools(Toolchain) P {
 	h := _make
 	if attr != nil && attr.Early {
 		h = _makeEarly
diff --git a/internal/rosa/meson.go b/internal/rosa/meson.go
index 25291dd0..59029595 100644
--- a/internal/rosa/meson.go
+++ b/internal/rosa/meson.go
@@ -3,6 +3,8 @@ package rosa
 import (
 	"slices"
 	"strings"
+
+	"hakurei.app/pkg"
 )
 
 var (
@@ -35,11 +37,54 @@ type MesonHelper struct {
 var _ Helper = new(MesonHelper)
 
 // tools returns hardcoded meson runtime dependencies.
-func (attr *MesonHelper) tools() P {
-	if !attr.isPython() {
-		return P{_muon}
+func (attr *MesonHelper) tools(t Toolchain) P {
+	m := _muon
+	if attr.isPython() {
+		m = _meson
+	}
+	if t.cross() {
+		return P{m, _qemu}
 	}
-	return P{_meson}
+	return P{m}
+}
+
+// paths returns the cross-compiler mfile, or nil if not cross-compiling.
+func (*MesonHelper) paths(t Toolchain) []pkg.ExecPath {
+	if !t.cross() {
+		return nil
+	}
+
+	arch, mesonArch, target := t.Arch(), t.linuxArch(), t.triple()
+	return []pkg.ExecPath{pkg.Path(
+		AbsSystem.Append("mfile"),
+		false, pkg.NewFile("mfile-"+arch, []byte(`# meson env2mfile
+[binaries]
+# Compilers
+c = ['clang', '--target=`+target+`', '--sysroot=/system/`+arch+`']
+cpp = ['clang++', '--target=`+target+`', '--sysroot=/system/`+arch+`']
+pkg-config = ['pkg-config']
+exe_wrapper = ['qemu-`+mesonArch+`', '-L', '/system/`+arch+`']
+
+# Other binaries
+ar = ['llvm-ar']
+ranlib = ['llvm-ranlib']
+strip = ['llvm-strip']
+
+[built-in options]
+
+[properties]
+sys_root = '/system/`+arch+`'
+pkg_config_libdir = '/system/`+arch+`/system/lib/pkgconfig'
+
+[host_machine]
+cpu = '`+mesonArch+`'
+cpu_family = '`+mesonArch+`'
+endian = 'little'
+system = 'linux'
+subsystem = 'linux'
+kernel = 'linux'
+`)),
+	)}
 }
 
 // inputs is a noop.
@@ -65,10 +110,6 @@ func (attr *MesonHelper) isPython() bool {
 
 // script generates the cure script.
 func (attr *MesonHelper) script(t Toolchain, name string) string {
-	if t.cross() {
-		panic(CrossError(name))
-	}
-
 	if attr == nil {
 		attr = new(MesonHelper)
 	}
@@ -109,8 +150,13 @@ func (attr *MesonHelper) script(t Toolchain, name string) string {
 		}
 	}
 
+	var setupArgs string
+	if t.cross() {
+		setupArgs += " --cross-file=/system/mfile"
+	}
+
 	return `
-` + muon + ` setup \
+` + muon + ` setup` + setupArgs + ` \
 	` + strings.Join(slices.Collect(func(yield func(string) bool) {
 		for _, v := range append([]KV{
 			{"wrap_mode", "nofallback"},
diff --git a/internal/rosa/package/wayland.az b/internal/rosa/package/wayland.az
index 3b240994..25f0c680 100644
--- a/internal/rosa/package/wayland.az
+++ b/internal/rosa/package/wayland.az
@@ -35,6 +35,9 @@ echo 'int main(){}' > tests/sanity-test.c
 		libexpat,
 		libxml2,
 	];
+
+	// for wayland-scanner
+	native = [ wayland ];
 }
 
 package wayland-protocols {
@@ -53,6 +56,7 @@ package wayland-protocols {
 	exec = meson {};
 
 	inputs = [ wayland ];
+	tools = [ wayland ];
 	runtime = nil;
 	unlikely = true;
 }
diff --git a/internal/rosa/perl.go b/internal/rosa/perl.go
index 55c17916..6cb87149 100644
--- a/internal/rosa/perl.go
+++ b/internal/rosa/perl.go
@@ -11,7 +11,7 @@ type MakeMakerHelper struct {
 }
 
 // tools returns perl and make.
-func (*MakeMakerHelper) tools() P { return P{_perl, _make} }
+func (*MakeMakerHelper) tools(Toolchain) P { return P{_perl, _make} }
 
 // inputs returns perl.
 func (*MakeMakerHelper) inputs() P { return P{_perl} }
diff --git a/internal/rosa/python.go b/internal/rosa/python.go
index e97ded49..8b363d87 100644
--- a/internal/rosa/python.go
+++ b/internal/rosa/python.go
@@ -26,7 +26,7 @@ type PipHelper struct {
 var _ Helper = new(PipHelper)
 
 // tools returns python and pytest if defaults are assumed.
-func (attr *PipHelper) tools() P {
+func (attr *PipHelper) tools(Toolchain) P {
 	if attr == nil || (!attr.SkipCheck && attr.Check == "") {
 		return P{_python, _pythonPyTest}
 	}
diff --git a/internal/rosa/rosa.go b/internal/rosa/rosa.go
index 27f31ecf..2448f203 100644
--- a/internal/rosa/rosa.go
+++ b/internal/rosa/rosa.go
@@ -214,6 +214,7 @@ var (
 	_toyboxEarly = H("toybox-early")
 	_llvm        = H("llvm")
 	_patch       = H("patch")
+	_qemu        = H("qemu")
 )
 
 // HasStageEarly returns whether a stage0 distribution is available.
@@ -281,7 +282,7 @@ const helperInPlace = "\x00"
 // Helper is a build system helper for [Toolchain.New].
 type Helper interface {
 	// tools returns helper-specific tool handles.
-	tools() P
+	tools(t Toolchain) P
 	// inputs returns helper-specific input handles.
 	inputs() P
 
@@ -301,6 +302,13 @@ type Helper interface {
 	script(t Toolchain, name string) string
 }
 
+// pathsHelper is a [Helper] with additional paths added to the container.
+type pathsHelper interface {
+	Helper
+
+	paths(t Toolchain) []pkg.ExecPath
+}
+
 // PackageAttr holds build-system-agnostic attributes.
 type PackageAttr struct {
 	// Measure output if populated. Required by HostNet.
@@ -515,7 +523,7 @@ func (t Toolchain) New(
 		if cross {
 			spv = paGet()
 		}
-		for _, p := range helper.tools() {
+		for _, p := range helper.tools(t) {
 			root = native.appendHandle(root, pv, p)
 		}
 
@@ -600,6 +608,9 @@ cd '/usr/src/` + name + `/'
 			)),
 		})
 	}
+	if ph, ok := helper.(pathsHelper); ok {
+		paths = append(paths, ph.paths(t)...)
+	}
 
 	bin := attr.Bin
 	if attr.PopulateUsrBin {
@@ -682,7 +693,7 @@ type GenericHelper struct {
 var _ Helper = new(GenericHelper)
 
 // tools is a noop.
-func (*GenericHelper) tools() P { return nil }
+func (*GenericHelper) tools(Toolchain) P { return nil }
 
 // inputs is a noop.
 func (*GenericHelper) inputs() P { return nil }