parser: warning about unused imports

cmd/tools/preludes/tests_assertions.v

@@ -1,7 +1,6 @@
 module main
 
 import os
-import term
 // //////////////////////////////////////////////////////////////////
 // / This file will get compiled as part of the main program,
 // / for a _test.v file.

vlib/v/ast/scope.v

@@ -4,7 +4,6 @@
 module ast
 
 import v.table
-import v.token
 
 pub struct Scope {
 //mut:

vlib/v/builder/builder.v

@@ -1,7 +1,6 @@
 module builder
 
 import os
-import time
 import v.ast
 import v.table
 import v.pref
@@ -9,10 +8,6 @@ import v.util
 import v.vmod
 import v.checker
 import v.parser
-import v.errors
-import v.gen
-import v.gen.js
-import v.gen.x64
 import v.depgraph
 
 const (

vlib/v/builder/compile.v

@@ -6,8 +6,6 @@ module builder
 import time
 import os
 import v.pref
-import v.util
-import strings
 
 fn get_vtmp_folder() string {
 	vtmp := os.join_path(os.temp_dir(), 'v')

vlib/v/builder/x64.v

@@ -1,7 +1,6 @@
 module builder
 
 import time
-import os
 import v.parser
 import v.pref
 import v.gen

vlib/v/checker/checker.v

@@ -4,13 +4,11 @@
 module checker
 
 import v.ast
-import v.depgraph
 import v.table
 import v.token
 import v.pref
 import v.util
 import v.errors
-import os
 
 const (
 	max_nr_errors = 300

vlib/v/checker/tests/import_not_found_err.vv

@@ -1,4 +1,4 @@
 import notexist
 fn main() {
-	println('hello, world')
+	println(notexist.name)
 }

vlib/v/checker/tests/import_unused_warning.out

@@ -0,0 +1,2 @@
+`vlib/v/checker/tests/import_unused_warning.v` warning: the following imports were never used:
+ * time

vlib/v/checker/tests/import_unused_warning.vv

@@ -0,0 +1,4 @@
+import time
+fn main() {
+	println('hello, world')
+}

vlib/v/gen/cheaders.v

@@ -1,7 +1,5 @@
 module gen
 
-import v.util
-
 // NB: @@@ here serve as placeholders.
 // They will be replaced with correct strings
 // for each constant, during C code generation.

vlib/v/gen/js/js.v

@@ -3,8 +3,6 @@ module js
 import strings
 import v.ast
 import v.table
-import v.depgraph
-import v.token
 import v.pref
 import term
 import v.util

vlib/v/gen/live.v

@@ -1,7 +1,5 @@
 module gen
 
-import os
-import time
 import v.pref
 import v.util
 

vlib/v/parser/assign.v

@@ -4,8 +4,6 @@
 module parser
 
 import v.ast
-import v.table
-import v.token
 
 fn (mut p Parser) assign_stmt() ast.Stmt {
 	is_static := p.tok.kind == .key_static

vlib/v/parser/for.v

@@ -5,7 +5,6 @@ module parser
 
 import v.ast
 import v.table
-import v.token
 
 fn (mut p Parser) for_stmt() ast.Stmt {
 	p.check(.key_for)

vlib/v/parser/module.v

@@ -17,3 +17,27 @@ fn (p &Parser) prepend_mod(name string) string {
 	}
 	return '${p.mod}.$name'
 }
+
+fn (p &Parser) is_used_import(alias string) bool {
+	return alias in p.used_imports
+}
+
+fn (mut p Parser) register_used_import(alias string) {
+	if alias !in p.used_imports {
+		p.used_imports << alias
+	}
+}
+
+fn (p mut Parser) check_unused_imports() {
+	mut output := ''
+	for alias, mod in p.imports {
+		if !p.is_used_import(alias) {
+			mod_alias := if alias == mod { alias } else { '$alias ($mod)' }
+			output += '\n * $mod_alias'
+		}
+	}
+	if output == '' {
+		return
+	}
+	eprintln('`$p.file_name` warning: the following imports were never used: $output')
+}

vlib/v/parser/parse_type.v

@@ -23,7 +23,7 @@ pub fn (mut p Parser) parse_array_type() table.Type {
 
 	// detect attr
 	not_attr := p.peek_tok.kind != .name && p.peek_tok2.kind !in [.semicolon, .rsbr]
-	
+
 	for p.tok.kind == .lsbr && not_attr {
 		p.next()
 		p.check(.rsbr)
@@ -146,6 +146,9 @@ pub fn (mut p Parser) parse_any_type(is_c, is_js, is_ptr bool) table.Type {
 			println(p.table.imports)
 			p.error('unknown module `$p.tok.lit`')
 		}
+		if p.tok.lit in p.imports {
+			p.register_used_import(p.tok.lit)
+		}
 		p.next()
 		p.check(.dot)
 		// prefix with full module

vlib/v/parser/parser.v

@@ -10,7 +10,6 @@ import v.table
 import v.pref
 import v.util
 import v.errors
-import term
 import os
 
 pub struct Parser {
@@ -38,8 +37,9 @@ mut:
 	expr_mod          string // for constructing full type names in parse_type()
 	scope             &ast.Scope
 	global_scope      &ast.Scope
-	imports           map[string]string
+	imports           map[string]string // alias => mod_name
-	ast_imports       []ast.Import
+	ast_imports       []ast.Import // mod_names
+	used_imports      []string // alias
 	is_amp            bool // for generating the right code for `&Foo{}`
 	returns           bool
 	inside_match      bool // to separate `match A { }` from `Struct{}`
@@ -115,6 +115,8 @@ pub fn parse_file(path string, b_table &table.Table, comments_mode scanner.Comme
 					file: p.file_name
 					return_type: table.void_type
 				}
+			} else {
+				p.check_unused_imports()
 			}
 			break
 		}
@@ -285,6 +287,9 @@ fn (mut p Parser) check(expected token.Kind) {
 
 fn (mut p Parser) check_name() string {
 	name := p.tok.lit
+	if p.peek_tok.kind == .dot && name in p.imports {
+		p.register_used_import(name)
+	}
 	p.check(.name)
 	return name
 }
@@ -697,6 +702,9 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 		} else if is_js {
 			mod = 'JS'
 		} else {
+			if p.tok.lit in p.imports {
+				p.register_used_import(p.tok.lit)
+			}
 			// prepend the full import
 			mod = p.imports[p.tok.lit]
 		}

vlib/v/pref/default.v

@@ -4,7 +4,6 @@
 module pref
 
 import os
-import term
 
 pub const (
 	default_module_path = mpath()