v2: report ill defined consts by name/line, not only how many they are

vlib/v/ast/ast.v

@@ -103,6 +103,8 @@ pub struct Field {
 pub:
 	name string
 	// type_idx int
+	pos token.Position
+	already_reported bool
 mut:
 	typ  table.Type
 	// typ2 Type

vlib/v/ast/str.v

@@ -65,20 +65,20 @@ pub fn (x Expr) str() string {
 		InfixExpr {
 			return '(${it.left.str()} $it.op.str() ${it.right.str()})'
 		}
-		/*
 		PrefixExpr {
-			return it.left.str() + it.op.str()
+			return it.op.str() + it.right.str()
 		}
-		*/
-
 		IntegerLiteral {
 			return it.val
 		}
 		StringLiteral {
 			return '"$it.val"'
 		}
+		ParExpr {
+			return it.expr.str()
+		}
 		else {
-			return ''
+			return '[unhandled expr type ${typeof(x)}]'
 		}
 	}
 }
@@ -113,7 +113,7 @@ pub fn (node Stmt) str() string {
 			return 'fn ${it.name}() { $it.stmts.len stmts }'
 		}
 		else {
-			return '[unhandled stmt str]'
+			return '[unhandled stmt str type: ${typeof(node)} ]'
 		}
 	}
 }

vlib/v/checker/checker.v

@@ -613,7 +613,17 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 				}
 			}
 			if unresolved_num != 0 {
-				c.error("$unresolved_num ill-defined consts are in use", it.pos)
+				for i, expr in it.exprs {
+					typ := c.expr(expr)
+					if typ == table.void_type {
+						mut _field := it.fields[i]
+						if !_field.already_reported {
+							_field.already_reported = true
+							it.fields[i] = _field
+							c.error("$unresolved_num ill-defined const `$_field.name`", _field.pos)
+						}
+					}
+				}
 			}
 			for i, field in ordered_fields { // set the fields and exprs as ordered
 				it.fields[i] = field

vlib/v/parser/parser.v

@@ -1452,6 +1452,7 @@ fn (p mut Parser) const_decl() ast.ConstDecl {
 		expr := p.expr(0)
 		fields << ast.Field{
 			name: name
+			pos: p.tok.position()
 			// typ: typ
 
 		}
@@ -1519,6 +1520,7 @@ fn (p mut Parser) struct_decl() ast.StructDecl {
 			p.check(.colon)
 		}
 		field_name := p.check_name()
+		field_pos := p.tok.position()
 		// p.warn('field $field_name')
 		typ := p.parse_type()
 		/*
@@ -1535,6 +1537,7 @@ fn (p mut Parser) struct_decl() ast.StructDecl {
 		}
 		ast_fields << ast.Field{
 			name: field_name
+			pos: field_pos
 			typ: typ
 		}
 		fields << table.Field{