fmt: remove unused selective imports (#8595)

doc/docs.md

@@ -865,8 +865,12 @@ You can also import specific functions and types from modules directly:
 
 ```v
 import os { input }
-import crypto.sha256 { sum }
-import time { Time }
+
+fn main() {
+	// read text from stdin
+	name := input('Enter your name: ')
+	println('Hello, $name!')
+}
 ```
 Note: This is not allowed for constants - they must always be prefixed.
 

vlib/v/fmt/fmt.v

@@ -36,9 +36,10 @@ pub mut:
 	file               ast.File
 	did_imports        bool
 	is_assign          bool
-	auto_imports       []string // automatically inserted imports that the user forgot to specify
-	import_pos         int      // position of the imports in the resulting string for later autoimports insertion
-	used_imports       []string // to remove unused imports
+	auto_imports       []string        // automatically inserted imports that the user forgot to specify
+	import_pos         int             // position of the imports in the resulting string for later autoimports insertion
+	used_imports       []string        // to remove unused imports
+	import_syms_used   map[string]bool // to remove unused import symbols.
 	is_debug           bool
 	mod2alias          map[string]string // for `import time as t`, will contain: 'time'=>'t'
 	use_short_fn_args  bool
@@ -82,6 +83,7 @@ pub fn (mut f Fmt) process_file_imports(file &ast.File) {
 		for sym in imp.syms {
 			f.mod2alias['${imp.mod}.$sym.name'] = sym.name
 			f.mod2alias[sym.name] = sym.name
+			f.import_syms_used[sym.name] = false
 		}
 	}
 	f.auto_imports = file.auto_imports
@@ -235,11 +237,15 @@ pub fn (mut f Fmt) mark_types_import_as_used(typ table.Type) {
 
 // `name` is a function (`foo.bar()`) or type (`foo.Bar{}`)
 pub fn (mut f Fmt) mark_import_as_used(name string) {
-	if !name.contains('.') {
+	parts := name.split('.')
+	last := parts.last()
+	if last in f.import_syms_used {
+		f.import_syms_used[last] = true
+	}
+	if parts.len == 1 {
 		return
 	}
-	pos := name.last_index('.') or { 0 }
-	mod := name[..pos]
+	mod := parts[0..parts.len - 1].join('.')
 	if mod in f.used_imports {
 		return
 	}
@@ -284,12 +290,13 @@ pub fn (mut f Fmt) imports(imports []ast.Import) {
 pub fn (f Fmt) imp_stmt_str(imp ast.Import) string {
 	is_diff := imp.alias != imp.mod && !imp.mod.ends_with('.' + imp.alias)
 	mut imp_alias_suffix := if is_diff { ' as $imp.alias' } else { '' }
-	if imp.syms.len > 0 {
-		names := imp.syms.map(it.name)
+
+	syms := imp.syms.map(it.name).filter(f.import_syms_used[it])
+	if syms.len > 0 {
 		imp_alias_suffix += if imp.syms[0].pos.line_nr == imp.pos.line_nr {
-			' { ' + names.join(', ') + ' }'
+			' { ' + syms.join(', ') + ' }'
 		} else {
-			' {\n\t' + names.join(',\n\t') + ',\n}'
+			' {\n\t' + syms.join(',\n\t') + ',\n}'
 		}
 	}
 	return '$imp.mod$imp_alias_suffix'
@@ -1218,6 +1225,7 @@ pub fn (mut f Fmt) ident(node ast.Ident) {
 					} else {
 						short := mod_prefix + '.' + const_name
 						f.write(short)
+						f.mark_import_as_used(short)
 						return
 					}
 				}
@@ -1226,9 +1234,7 @@ pub fn (mut f Fmt) ident(node ast.Ident) {
 		name := f.short_module(node.name)
 		// f.write('<$it.name => $name>')
 		f.write(name)
-		if name.contains('.') {
-			f.mark_import_as_used(name)
-		}
+		f.mark_import_as_used(name)
 	}
 }
 
@@ -1911,6 +1917,7 @@ fn should_decrease_arr_penalty(e ast.Expr) bool {
 pub fn (mut f Fmt) array_init(it ast.ArrayInit) {
 	if it.exprs.len == 0 && it.typ != 0 && it.typ != table.void_type {
 		// `x := []string{}`
+		f.mark_types_import_as_used(it.typ)
 		f.write(f.table.type_to_str_using_aliases(it.typ, f.mod2alias))
 		f.write('{')
 		if it.has_len {
@@ -2022,6 +2029,7 @@ pub fn (mut f Fmt) array_init(it ast.ArrayInit) {
 
 pub fn (mut f Fmt) map_init(it ast.MapInit) {
 	if it.keys.len == 0 {
+		f.mark_types_import_as_used(it.typ)
 		f.write(f.table.type_to_str(it.typ))
 		f.write('{}')
 		return
@@ -2064,9 +2072,11 @@ pub fn (mut f Fmt) struct_init(it ast.StructInit) {
 			f.comments(it.pre_comments, inline: true, has_nl: true, level: .indent)
 			f.write('}')
 		}
+		f.mark_import_as_used(name)
 	} else if it.is_short {
 		// `Foo{1,2,3}` (short syntax )
 		f.write('$name{')
+		f.mark_import_as_used(name)
 		if it.has_update_expr {
 			f.write('...')
 			f.expr(it.update_expr)
@@ -2089,6 +2099,7 @@ pub fn (mut f Fmt) struct_init(it ast.StructInit) {
 		}
 		if !use_short_args {
 			f.write('$name{')
+			f.mark_import_as_used(name)
 			if single_line_fields {
 				f.write(' ')
 			}

vlib/v/fmt/tests/import_selective_expected.vv

@@ -1,5 +1,12 @@
 import math { max, min }
 import os {
-	input,
 	user_os,
+	file_ext,
+}
+
+fn main() {
+	println(max(0.1, 0.2))
+	println(min(0.1, 0.2))
+	println(user_os())
+	println(file_ext('main.v'))
 }

vlib/v/fmt/tests/import_selective_input.vv

@@ -2,5 +2,11 @@ import math { max,
 	min,
 }
 import os {
-	input, user_os }
+	input, user_os, file_ext }
 
+fn main() {
+	println(max(0.1, 0.2))
+	println(min(0.1, 0.2))
+	println(user_os())
+	println(file_ext('main.v'))
+}