Add DUNE_CROSS_TARGET

Signed-off-by: Romain Beauxis <[email protected]>

Author: toots

bin/common.ml

@@ -865,10 +865,11 @@ module Builder = struct
       =
       Options_implied_by_dash_p.term
     and+ x =
+      let doc = "Cross-compile using this toolchain." in
       Arg.(
         value
         & opt (some Arg.context_name) None
-        & info [ "x" ] ~docs ~doc:(Some "Cross-compile using this toolchain."))
+        & info [ "x" ] ~docs ~doc:(Some doc) ~env:(Cmd.Env.info ~doc "DUNE_CROSS_TARGET"))
     and+ target_exec =
       let doc =
         "Wrapper command for running target binaries when cross-compiling. Format: \

test/blackbox-tests/test-cases/custom-cross-compilation/target-exec.t

@@ -137,6 +137,29 @@ Build with -x test_toolchain and environment variable DUNE_TARGET_EXEC=test_tool
   ---- HELLO END ----
 
 
+Build with environment variables DUNE_CROSS_TARGET=test_toolchain and DUNE_TARGET_EXEC=test_toolchain=test_toolchain_wrapper.sh
+(should cross compile and use target binary ./hello.exe wrapped with the wrapper)
+
+  $ PATH="$PWD/bin:$PATH" DUNE_CROSS_TARGET=test_toolchain DUNE_TARGET_EXEC=test_toolchain=test_toolchain_wrapper.sh dune build @runhello --force
+  ---- HELLO START ----
+  Hello from OCaml!
+  PWD: $TESTCASE_ROOT/_build/default
+  Args: ./hello.exe --hello-arg1 --hello-arg2
+  ---- HELLO END ----
+  
+  === TEST_TOOLCHAIN WRAPPER START ===
+  WRAPPER PWD: $TESTCASE_ROOT/_build/default.test_toolchain
+  WRAPPER executing: $TESTCASE_ROOT/_build/default.test_toolchain/hello.exe --hello-arg1 --hello-arg2
+  === WRAPPER EXEC ===
+  ---- HELLO START ----
+  Hello from OCaml!
+  PWD: $TESTCASE_ROOT/_build/default.test_toolchain
+  Args: $TESTCASE_ROOT/_build/default.test_toolchain/hello.exe --hello-arg1 --hello-arg2
+  ---- HELLO END ----
+  
+
+
+
 
 Build with -x test_toolchain and --target-exec with arguments
 (should use target binary ./hello.exe wrapped with the wrapper)