backends: Stop passing generator exes to ExecutableSerialisation as strings

The code below this already handles being passed an Executable or
ExternalProgram, and it does it correctly, since it handles host
binaries that need an exe_wrapper correctly, while the code in the
generator paths doesn't.

The xcode backend is, like always, problematic, it doesn't handle things
the same way as the ninja and vscode backends, and generates a shell
script instead of using meson as a wrapper when needed (it seems likely
that just forcing the meson path for xcode would be better). I don't
have a working mac to develop a fix for, so I've left a todo comment
there.

Fixes: #11264

10 files changed, 87 insertions, 7 deletions

diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 093e2ef..3c8bb81 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -2388,7 +2388,6 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         generator = genlist.get_generator()
         subdir = genlist.subdir
         exe = generator.get_exe()
-        exe_arr = self.build_target_to_cmd_array(exe)
         infilelist = genlist.get_inputs()
         outfilelist = genlist.get_outputs()
         extra_dependencies = self.get_custom_target_depend_files(genlist)
@@ -2416,8 +2415,8 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
             if len(generator.outputs) > 1:
                 outfilelist = outfilelist[len(generator.outputs):]
             args = self.replace_paths(target, args, override_subdir=subdir)
-            cmdlist = exe_arr + self.replace_extra_args(args, genlist)
-            cmdlist, reason = self.as_meson_exe_cmdline(cmdlist[0], cmdlist[1:],
+            cmdlist, reason = self.as_meson_exe_cmdline(exe,
+                                                        self.replace_extra_args(args, genlist),
                                                         capture=outfiles[0] if generator.capture else None)
             abs_pdir = os.path.join(self.environment.get_build_dir(), self.get_target_dir(target))
             os.makedirs(abs_pdir, exist_ok=True)
diff --git a/mesonbuild/backend/vs2010backend.py b/mesonbuild/backend/vs2010backend.py
index 20cff56..cf15175 100644
--- a/mesonbuild/backend/vs2010backend.py
+++ b/mesonbuild/backend/vs2010backend.py
@@ -137,7 +137,6 @@ class Vs2010Backend(backends.Backend):
                 infilelist = genlist.get_inputs()
                 outfilelist = genlist.get_outputs()
                 source_dir = os.path.join(down, self.build_to_src, genlist.subdir)
-                exe_arr = self.build_target_to_cmd_array(exe)
                 idgroup = ET.SubElement(parent_node, 'ItemGroup')
                 for i, curfile in enumerate(infilelist):
                     if len(infilelist) == len(outfilelist):
@@ -161,13 +160,12 @@ class Vs2010Backend(backends.Backend):
                              .replace("@BUILD_ROOT@", self.environment.get_build_dir())
                             for x in args]
                     args = [x.replace('\\', '/') for x in args]
-                    cmd = exe_arr + self.replace_extra_args(args, genlist)
                     # Always use a wrapper because MSBuild eats random characters when
                     # there are many arguments.
                     tdir_abs = os.path.join(self.environment.get_build_dir(), self.get_target_dir(target))
                     cmd, _ = self.as_meson_exe_cmdline(
-                        cmd[0],
-                        cmd[1:],
+                        exe,
+                        self.replace_extra_args(args, genlist),
                         workdir=tdir_abs,
                         capture=outfiles[0] if generator.capture else None,
                         force_serialize=True
diff --git a/mesonbuild/backend/xcodebackend.py b/mesonbuild/backend/xcodebackend.py
index c56036b..605ee22 100644
--- a/mesonbuild/backend/xcodebackend.py
+++ b/mesonbuild/backend/xcodebackend.py
@@ -1219,6 +1219,8 @@ class XCodeBackend(backends.Backend):
                     generator_id += 1
 
     def generate_single_generator_phase(self, tname, t, genlist, generator_id, objects_dict):
+        # TODO: this should be rewritten to use the meson wrapper, like the other generators do
+        # Currently it doesn't handle a host binary that requires an exe wrapper correctly.
         generator = genlist.get_generator()
         exe = generator.get_exe()
         exe_arr = self.build_target_to_cmd_array(exe)
diff --git a/test cases/common/105 generatorcustom/gen.c b/test cases/common/105 generatorcustom/gen.c
new file mode 100644
index 0000000..59518c0
--- /dev/null
+++ b/test cases/common/105 generatorcustom/gen.c
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+/* Copyright © 2023 Intel Corporation */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, const char ** argv) {
+    if (argc != 3) {
+        fprintf(stderr, "%s %i %s\n", "Got incorrect number of arguments, got ", argc - 1, ", but expected 2");
+        exit(1);
+    }
+
+    FILE * input, * output;
+
+    if ((input = fopen(argv[1], "rb")) == NULL) {
+        exit(1);
+    }
+    if ((output = fopen(argv[2], "wb")) == NULL) {
+        exit(1);
+    }
+
+    fprintf(output, "#pragma once\n");
+    fprintf(output, "#define ");
+
+    char c;
+    while((c = fgetc(input)) != EOF) {
+        fputc(c, output);
+    }
+    fputc('\n', output);
+
+    fclose(input);
+    fclose(output);
+
+    return 0;
+}
diff --git a/test cases/common/105 generatorcustom/host.c b/test cases/common/105 generatorcustom/host.c
new file mode 100644
index 0000000..1ddfa88
--- /dev/null
+++ b/test cases/common/105 generatorcustom/host.c
@@ -0,0 +1,9 @@
+#include "res1-cpp.h"
+
+int main(void) {
+    #ifdef res1
+        return 0;
+    #else
+        return 1;
+    #endif
+}
diff --git a/test cases/common/105 generatorcustom/meson.build b/test cases/common/105 generatorcustom/meson.build
index 2128d21..dab55de 100644
--- a/test cases/common/105 generatorcustom/meson.build
+++ b/test cases/common/105 generatorcustom/meson.build
@@ -26,3 +26,19 @@ allinone = custom_target('alltogether',
 proggie = executable('proggie', 'main.c', allinone)
 
 test('proggie', proggie)
+
+# specifically testing that cross binaries are run with an exe_wrapper
+if meson.can_run_host_binaries()
+  gen_tool = executable('generator', 'gen.c', native : false)
+
+  c_gen = generator(
+    gen_tool,
+    output : '@BASENAME@-cpp.h',
+    arguments : ['@INPUT@', '@OUTPUT@']
+  )
+
+  hs2 = c_gen.process('res1.txt')
+
+  host_exe = executable('host_test', 'host.c', hs2, native : false)
+  test('compiled generator', host_exe)
+endif
diff --git a/test cases/failing/129 generator host binary/exe.c b/test cases/failing/129 generator host binary/exe.c
new file mode 100644
index 0000000..78f2de1
--- /dev/null
+++ b/test cases/failing/129 generator host binary/exe.c
@@ -0,0 +1 @@
+int main(void) { return 0; }
diff --git a/test cases/failing/129 generator host binary/lib.in b/test cases/failing/129 generator host binary/lib.in
new file mode 100644
index 0000000..d0b6ab7
--- /dev/null
+++ b/test cases/failing/129 generator host binary/lib.in
@@ -0,0 +1 @@
+int foo(void) { return 7; }
diff --git a/test cases/failing/129 generator host binary/meson.build b/test cases/failing/129 generator host binary/meson.build
new file mode 100644
index 0000000..fc1f9be
--- /dev/null
+++ b/test cases/failing/129 generator host binary/meson.build
@@ -0,0 +1,14 @@
+project('generator host binary no exe_wrapper')
+
+if meson.can_run_host_binaries()
+  error('MESON_SKIP_TEST: test requires that build machine cannot run host binaries')
+endif
+
+add_languages('c', native : false)
+
+exe = executable('exe', 'exe.c', native : false)
+
+gen = generator(exe, output : '@BASENAME@.c', arguments : ['@INPUT@', '@OUTPU@'])
+foo = gen.process('lib.in')
+
+library('foo', foo)
diff --git a/test cases/failing/129 generator host binary/test.json b/test cases/failing/129 generator host binary/test.json
new file mode 100644
index 0000000..7e354d6
--- /dev/null
+++ b/test cases/failing/129 generator host binary/test.json
@@ -0,0 +1,5 @@
+{
+  "stdout": [
+    { "line": "ERROR: An exe_wrapper is needed but was not found. Please define one in cross file and check the command and/or add it to PATH." }
+  ]
+}