v.parser: improve the unused import warning message (add fixing alternatives) (#25880)

Author: spytheman

vlib/v/checker/tests/decompose_interface_err.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/decompose_interface_err.vv:3:8: warning: module 'arrays' is imported but never used
+vlib/v/checker/tests/decompose_interface_err.vv:3:8: warning: module 'arrays' is imported but never used. Use `import arrays as _`, to silence this warning, or just remove the unused import line
     1 | module main
     2 | 
     3 | import arrays

vlib/v/checker/tests/fn_param_import_sym_conflict.out

@@ -1,15 +1,15 @@
-vlib/v/checker/tests/fn_param_import_sym_conflict.vv:1:8: warning: module 'arrays' is imported but never used
+vlib/v/checker/tests/fn_param_import_sym_conflict.vv:1:8: warning: module 'arrays' is imported but never used. Use `import arrays as _`, to silence this warning, or just remove the unused import line
     1 | import arrays
       |        ~~~~~~
     2 | import maps
     3 | import strings as strs
-vlib/v/checker/tests/fn_param_import_sym_conflict.vv:2:8: warning: module 'maps' is imported but never used
+vlib/v/checker/tests/fn_param_import_sym_conflict.vv:2:8: warning: module 'maps' is imported but never used. Use `import maps as _`, to silence this warning, or just remove the unused import line
     1 | import arrays
     2 | import maps
       |        ~~~~
     3 | import strings as strs
     4 |
-vlib/v/checker/tests/fn_param_import_sym_conflict.vv:3:8: warning: module 'strs (strings)' is imported but never used
+vlib/v/checker/tests/fn_param_import_sym_conflict.vv:3:8: warning: module 'strs (strings)' is imported but never used. Use `import strs (strings) as _`, to silence this warning, or just remove the unused import line
     1 | import arrays
     2 | import maps
     3 | import strings as strs

vlib/v/checker/tests/import_symbol_fn_err.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/import_symbol_fn_err.vv:1:8: warning: module 'crypto' is imported but never used
+vlib/v/checker/tests/import_symbol_fn_err.vv:1:8: warning: module 'crypto' is imported but never used. Use `import crypto as _`, to silence this warning, or just remove the unused import line
     1 | import crypto { userper }
       |        ~~~~~~
     2 | fn main() {

vlib/v/checker/tests/import_unused_warning.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/import_unused_warning.vv:2:8: warning: module 'time' is imported but never used
+vlib/v/checker/tests/import_unused_warning.vv:2:8: warning: module 'time' is imported but never used. Use `import time as _`, to silence this warning, or just remove the unused import line
     1 | import os as _
     2 | import time
       |        ~~~~

vlib/v/checker/tests/incorrect_name_module.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/incorrect_name_module.vv:4:8: warning: module 'os' is imported but never used
+vlib/v/checker/tests/incorrect_name_module.vv:4:8: warning: module 'os' is imported but never used. Use `import os as _`, to silence this warning, or just remove the unused import line
     2 | 
     3 | import math as _
     4 | import os

vlib/v/checker/tests/os_prefix.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/os_prefix.vv:1:8: warning: module 'os' is imported but never used
+vlib/v/checker/tests/os_prefix.vv:1:8: warning: module 'os' is imported but never used. Use `import os as _`, to silence this warning, or just remove the unused import line
     1 | import os
       |        ~~
     2 | 

vlib/v/checker/tests/selective_const_import.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/selective_const_import.vv:1:8: warning: module 'time' is imported but never used
+vlib/v/checker/tests/selective_const_import.vv:1:8: warning: module 'time' is imported but never used. Use `import time as _`, to silence this warning, or just remove the unused import line
     1 | import time { second }
       |        ~~~~
 vlib/v/checker/tests/selective_const_import.vv:1:15: error: cannot selectively import constant `second` from `time`, import `time` and use `time.second` instead

vlib/v/checker/tests/unused_import_err.out

@@ -1,8 +1,8 @@
-vlib/v/checker/tests/unused_import_err.vv:1:8: warning: module 'te (term)' is imported but never used
+vlib/v/checker/tests/unused_import_err.vv:1:8: warning: module 'te (term)' is imported but never used. Use `import te (term) as _`, to silence this warning, or just remove the unused import line
     1 | import term as te
       |        ~~~~
     2 | import te.ui
-vlib/v/checker/tests/unused_import_err.vv:2:8: warning: module 'ui (te.ui)' is imported but never used
+vlib/v/checker/tests/unused_import_err.vv:2:8: warning: module 'ui (te.ui)' is imported but never used. Use `import ui (te.ui) as _`, to silence this warning, or just remove the unused import line
     1 | import term as te
     2 | import te.ui
       |        ~~~~~

vlib/v/checker/tests/var_decl_import_sym_conflict.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/var_decl_import_sym_conflict.vv:1:8: warning: module 'arrays' is imported but never used
+vlib/v/checker/tests/var_decl_import_sym_conflict.vv:1:8: warning: module 'arrays' is imported but never used. Use `import arrays as _`, to silence this warning, or just remove the unused import line
     1 | import arrays
       |        ~~~~~~
     2 | 

vlib/v/parser/module.v

@@ -89,7 +89,8 @@ fn (mut p Parser) check_unused_imports() {
 		if !(alias.len == 1 && alias[0] == `_`) && !p.is_used_import(alias)
 			&& alias !in p.auto_imports {
 			mod_alias := if alias == mod { alias } else { '${alias} (${mod})' }
-			p.warn_with_pos("module '${mod_alias}' is imported but never used", import_m.mod_pos)
+			p.warn_with_pos("module '${mod_alias}' is imported but never used. Use `import ${mod_alias} as _`, to silence this warning, or just remove the unused import line",
+				import_m.mod_pos)
 		}
 	}
 }