parser: show location of a previously defined function

vlib/v/builder/builder.v

@@ -212,10 +212,8 @@ fn (b &Builder) print_warnings_and_errors() {
 		if b.checker.nr_errors > 0 {
 			exit(1)
 		}
-
 		return
 	}
-
 	if b.pref.is_verbose && b.checker.nr_warnings > 1 {
 		println('$b.checker.nr_warnings warnings')
 	}
@@ -246,6 +244,24 @@ fn (b &Builder) print_warnings_and_errors() {
 		}
 		exit(1)
 	}
+	if b.table.redefined_fns.len > 0 {
+		for fn_name in b.table.redefined_fns {
+			eprintln('redefinition of function `$fn_name`')
+			// eprintln('previous declaration at')
+			// Find where this function was already declared
+			for file in b.parsed_files {
+				for stmt in file.stmts {
+					if stmt is ast.FnDecl {
+						f := stmt as ast.FnDecl
+						if f.name == fn_name {
+							println(file.path + ':' + f.pos.line_nr.str())
+						}
+					}
+				}
+			}
+			exit(1)
+		}
+	}
 }
 
 fn verror(s string) {

vlib/v/parser/fn.v

@@ -456,7 +456,8 @@ fn (mut p Parser) fn_redefinition_error(name string) {
 
 	}
 	*/
-	p.error('redefinition of function `$name`')
+	p.table.redefined_fns << name
+	// p.error('redefinition of function `$name`')
 }
 
 fn have_fn_main(stmts []ast.Stmt) bool {

vlib/v/parser/parser.v

@@ -1044,7 +1044,11 @@ fn (mut p Parser) string_expr() ast.Expr {
 		node = ast.StringLiteral{
 			val: val
 			is_raw: is_raw
-			language: if is_cstr { table.Language.c } else { table.Language.v }
+			language: if is_cstr {
+				table.Language.c
+			} else {
+				table.Language.v
+			}
 			pos: pos
 		}
 		return node

vlib/v/table/table.v

@@ -14,6 +14,7 @@ pub mut:
 	imports   []string // List of all imports
 	modules   []string // List of all modules registered by the application
 	cflags    []cflag.CFlag
+	redefined_fns     []string
 }
 
 pub struct Fn {