LibJS: Ensure asmintgen works even when CARGO_TARGET_DIR is set

Problem: Build fails when CARGO_TARGET_DIR is set.

Cause: The asmintgen custom command ran a bare “cargo build --release”,
which wrote the binary to any CARGO_TARGET_DIR set. But the build looked
for it under a hardcoded AsmIntGen/target path — and didn’t find it.

Fix: Build asmintgen with build_rust_binary() from rust_crate.cmake —
the same helper we already build all other crates with. That passes an
explicit --target-dir, which causes CARGO_TARGET_DIR to be ignored.

Fixes #10216

Author: sideshowbarker

Libraries/LibJS/CMakeLists.txt

@@ -336,8 +336,6 @@ if (DEFINED ASMINT_ARCH)
         set(CMAKE_ASM_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_ProgramDatabase "")
         set(CMAKE_ASM_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_EditAndContinue "")
     endif()
-    set(ASMINTGEN_DIR "${CMAKE_CURRENT_SOURCE_DIR}/AsmIntGen")
-    set(ASMINTGEN_BIN "${ASMINTGEN_DIR}/target/release/asmintgen${CMAKE_EXECUTABLE_SUFFIX}")
     set(ASMINT_DSL "${CMAKE_CURRENT_SOURCE_DIR}/Bytecode/AsmInterpreter/asmint.asm")
     set(ASMINT_GENERATED_S "${CMAKE_CURRENT_BINARY_DIR}/Bytecode/AsmInterpreter/asmint_${ASMINT_ARCH}.S")
     set(ASM_OFFSETS_FILE "${CMAKE_CURRENT_BINARY_DIR}/Bytecode/AsmInterpreter/asm_offsets.conf")
@@ -365,36 +363,11 @@ if (DEFINED ASMINT_ARCH)
         COMMENT "Generating asm struct offsets"
     )
 
-    file(GLOB ASMINTGEN_RUST_SOURCES CONFIGURE_DEPENDS "${ASMINTGEN_DIR}/src/*.rs")
-    file(GLOB ASMINTGEN_BYTECODE_DEF_SOURCES CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/BytecodeDef/src/*.rs")
-    set(ASMINTGEN_SOURCES
-        "${ASMINTGEN_DIR}/Cargo.toml"
-        "${ASMINTGEN_DIR}/Cargo.lock"
-        "${CMAKE_CURRENT_SOURCE_DIR}/BytecodeDef/Cargo.toml"
-        ${ASMINTGEN_RUST_SOURCES}
-        ${ASMINTGEN_BYTECODE_DEF_SOURCES}
-    )
-    # NB: Clear linker-related env vars so cargo uses the default host
-    # linker. The CI may set CC/CXX or CARGO_TARGET_*_LINKER to a
-    # compiler that isn't available in all build configurations (e.g.
-    # clang-21 in GNU builds). asmintgen is a pure Rust host tool.
-    add_custom_command(
-        OUTPUT "${ASMINTGEN_BIN}"
-        COMMAND ${CMAKE_COMMAND}
-            -DLOG=${CMAKE_CURRENT_BINARY_DIR}/cargo-asmintgen.log
-            -P "${LADYBIRD_SOURCE_DIR}/Meta/CMake/run_quiet.cmake"
-            --
-            ${CMAKE_COMMAND} -E env
-            --unset=CC
-            --unset=CXX
-            --unset=CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER
-            --unset=CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER
-            CARGO_TERM_PROGRESS_WHEN=never TERM=dumb
-            cargo build --release
-        WORKING_DIRECTORY "${ASMINTGEN_DIR}"
-	 JOB_POOL cargo
-        DEPENDS ${ASMINTGEN_SOURCES}
-        COMMENT "Building asmintgen"
+    build_rust_binary(
+        MANIFEST_PATH AsmIntGen/Cargo.toml
+        CRATE_NAME asmintgen
+        BINARY_NAME asmintgen
+        OUTPUT_PATH_VAR ASMINTGEN_BIN
     )
 
     set(BYTECODE_DEF "${CMAKE_CURRENT_SOURCE_DIR}/Bytecode/Bytecode.def")