继续按 align-linuxcnc 约束：补增强块轴值错误源码覆盖，测试通过

test-linuxcnc-source-link.sh

@@ -576,6 +576,29 @@ for case in "${polar_coordinate_error_cases[@]}"; do
     fi
     grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_source_$fixture.err"
 done
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_internal.cc
+# enhance_block() assigns motion_to_be and rejects invalid axis use with G80,
+# missing axes for G52/G92 or motion codes, bare axis words without active
+# motion, and modal-0 G codes that consume axis values on a motion block.
+enhance_block_error_cases=(
+    "linuxcnc_g80_axis_error|Cannot use axis values with g80"
+    "linuxcnc_g52_missing_axis_error|All axes missing with g52 or g92"
+    "linuxcnc_g92_missing_axis_error|All axes missing with g52 or g92"
+    "linuxcnc_motion_missing_axis_error|All axes missing with motion code"
+    "linuxcnc_axis_without_motion_error|Cannot use axis values without a g code that uses them"
+    "linuxcnc_motion_with_g92_axis_error|Cannot use two g codes that both use axis values"
+)
+for case in "${enhance_block_error_cases[@]}"; do
+    fixture=${case%%|*}
+    expected=${case#*|}
+    if CNC_SIM_RS274_VAR="$var_file" \
+        "$build_dir/linuxcnc_rs274_source_dump" "tests/gcode/$fixture.ngc" \
+        >"$output_dir/cnc_sim_linuxcnc_source_$fixture.json" 2>"$output_dir/cnc_sim_linuxcnc_source_$fixture.err"; then
+        echo "expected $fixture.ngc to fail" >&2
+        exit 1
+    fi
+    grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_source_$fixture.err"
+done
 CNC_SIM_RS274_VAR="$var_file" \
     "$build_dir/linuxcnc_rs274_source_dump" tests/gcode/linuxcnc_predefined_positions.ngc \
     >"$output_dir/cnc_sim_linuxcnc_source_predefined_positions.json"