[SYCL] Add flag to print CMake args without execution to buildbot.py (#19636)

Adds a `--print-cmake-flags` option to the configure.py helper script.

When used, the script will print the generated list of CMake arguments
to stdout and exit immediately. This suppresses all other output and
does not invoke the cmake command.

This is useful for packaging or integrating with build systems that
need/prefer to call cmake manually.

Tagging @sarnex

Author: blenderfreaky

buildbot/configure.py

@@ -137,9 +137,10 @@ def do_configure(args, passthrough_args):
     # CI Default conditionally appends to options, keep it at the bottom of
     # args handling
     if args.ci_defaults:
-        print("#############################################")
-        print("# Default CI configuration will be applied. #")
-        print("#############################################")
+        if not args.print_cmake_flags:
+            print("#############################################")
+            print("# Default CI configuration will be applied. #")
+            print("#############################################")
 
         # For clang-format, clang-tidy and code coverage
         llvm_enable_projects += ";clang-tools-extra;compiler-rt"
@@ -255,20 +256,24 @@ def do_configure(args, passthrough_args):
         )
 
     cmake_cmd += passthrough_args
-    print("[Cmake Command]: {}".format(" ".join(map(shlex.quote, cmake_cmd))))
-
-    try:
-        subprocess.check_call(cmake_cmd, cwd=abs_obj_dir)
-    except subprocess.CalledProcessError:
-        cmake_cache = os.path.join(abs_obj_dir, "CMakeCache.txt")
-        if os.path.isfile(cmake_cache):
-            print(
-                "There is CMakeCache.txt at "
-                + cmake_cache
-                + " ... you can try to remove it and rerun."
-            )
-            print("Configure failed!")
-        return False
+
+    if args.print_cmake_flags:
+        print(" ".join(map(shlex.quote, cmake_cmd[1:])))
+    else:
+        print("[Cmake Command]: {}".format(" ".join(map(shlex.quote, cmake_cmd))))
+
+        try:
+            subprocess.check_call(cmake_cmd, cwd=abs_obj_dir)
+        except subprocess.CalledProcessError:
+            cmake_cache = os.path.join(abs_obj_dir, "CMakeCache.txt")
+            if os.path.isfile(cmake_cache):
+                print(
+                    "There is CMakeCache.txt at "
+                    + cmake_cache
+                    + " ... you can try to remove it and rerun."
+                )
+                print("Configure failed!")
+            return False
 
     return True
 
@@ -411,9 +416,15 @@ def main():
     parser.add_argument(
         "--use-zstd", action="store_true", help="Force zstd linkage while building."
     )
+    parser.add_argument(
+        "--print-cmake-flags",
+        action="store_true",
+        help="Print the generated CMake flags to a single line on standard output and exit. Suppresses all other output and does not run the cmake command.",
+    )
     args, passthrough_args = parser.parse_known_intermixed_args()
 
-    print("args:{}".format(args))
+    if not args.print_cmake_flags:
+        print("args:{}".format(args))
 
     return do_configure(args, passthrough_args)