parser/checker/gen: match shaddow cond var & as support: p1

vlib/v/ast/ast.v

@@ -442,6 +442,7 @@ pub:
 	branches      []MatchBranch
 	pos           token.Position
 	is_mut        bool // `match mut ast_node {`
+	var_name      string
 pub mut:
 	is_expr       bool // returns a value
 	return_type   table.Type

vlib/v/ast/str.v

@@ -126,22 +126,33 @@ pub fn (lit &StringInterLiteral) get_fspec_braces(i int) (string, bool) {
 			}
 		}
 	}
+	// TODO: remove sponge - put back match
 	if !needs_braces {
 		mut sub_expr := lit.exprs[i]
 		for {
-			match sub_expr {
-				Ident {
-					break
-				}
-				SelectorExpr {
-					sub_expr = it.expr
-					continue
-				}
-				else {
-					needs_braces = true
-					break
-				}
+			if sub_expr is Ident { break }
+			else if sub_expr is SelectorExpr {
+				se := sub_expr as SelectorExpr
+				sub_expr = se.expr
+				continue
 			}
+			else {
+				needs_braces = true
+				break
+			}
+			// match sub_expr {
+			// 	Ident {
+			// 		break
+			// 	}
+			// 	SelectorExpr {
+			// 		sub_expr = it.expr
+			// 		continue
+			// 	}
+			// 	else {
+			// 		needs_braces = true
+			// 		break
+			// 	}
+			// }
 		}
 	}
 	if needs_fspec {

vlib/v/checker/check_types.v

@@ -93,13 +93,15 @@ pub fn (c &Checker) check_basic(got, expected table.Type) bool {
 		return true
 	}
 	// sum type
-	if got_type_sym.kind == .sum_type {
-		sum_info := got_type_sym.info as table.SumType
-		// TODO: handle `match SumType { &PtrVariant {} }` currently just checking base
-		if expected.set_nr_muls(0) in sum_info.variants {
-			return true
-		}
-	}
+	// TODO: there is a bug when casting sumtype the other way if its pointer
+	// so until fixed at least show v (not C) error `x(variant) =  y(SumType*)`
+	// if got_type_sym.kind == .sum_type {
+	// 	sum_info := got_type_sym.info as table.SumType
+	// 	// TODO: handle `match SumType { &PtrVariant {} }` currently just checking base
+	// 	if expected.set_nr_muls(0) in sum_info.variants {
+	// 		return true
+	// 	}
+	// }
 	if exp_type_sym.kind == .sum_type {
 		sum_info := exp_type_sym.info as table.SumType
 		// TODO: handle `match SumType { &PtrVariant {} }` currently just checking base

vlib/v/checker/checker.v

@@ -170,19 +170,19 @@ fn (mut c Checker) check_file_in_main(file ast.File) bool {
 				}
 			}
 			ast.TypeDecl {
-				type_decl := stmt as ast.TypeDecl
-				if type_decl is ast.AliasTypeDecl {
-					alias_decl := type_decl as ast.AliasTypeDecl
+				// type_decl := stmt as ast.TypeDecl
+				if it is ast.AliasTypeDecl {
+					alias_decl := it as ast.AliasTypeDecl
 					if alias_decl.is_pub {
 						c.warn('type alias `$alias_decl.name` $no_pub_in_main_warning', alias_decl.pos)
 					}
-				} else if type_decl is ast.SumTypeDecl {
-					sum_decl := type_decl as ast.SumTypeDecl
+				} else if it is ast.SumTypeDecl {
+					sum_decl := it as ast.SumTypeDecl
 					if sum_decl.is_pub {
 						c.warn('sum type `$sum_decl.name` $no_pub_in_main_warning', sum_decl.pos)
 					}
-				} else if type_decl is ast.FnTypeDecl {
-					fn_decl := type_decl as ast.FnTypeDecl
+				} else if it is ast.FnTypeDecl {
+					fn_decl := it as ast.FnTypeDecl
 					if fn_decl.is_pub {
 						c.warn('type alias `$fn_decl.name` $no_pub_in_main_warning', fn_decl.pos)
 					}

vlib/v/gen/cgen.v

@@ -1227,7 +1227,9 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 }
 
 fn (mut g Gen) gen_cross_tmp_variable(left []ast.Expr, val ast.Expr) {
-	match val {
+	// TODO: remove sponge
+	tmp_val := val
+	match tmp_val {
 		ast.Ident {
 			mut has_var := false
 			for lx in left {
@@ -1987,6 +1989,10 @@ fn (mut g Gen) match_expr(node ast.MatchExpr) {
 					g.write('\t$it_type* it = ($it_type*)')
 					g.expr(node.cond)
 					g.writeln('.obj; // ST it')
+					if node.var_name.len > 0 {
+						// for now we just copy it
+						g.writeln('\t$it_type* $node.var_name = it;')
+					}
 				}
 				else {
 					verror('match sum type')

vlib/v/gen/x64/gen.v

@@ -559,8 +559,7 @@ pub fn (mut g Gen) call_fn(node ast.CallExpr) {
 		match expr {
 			ast.IntegerLiteral {
 				// `foo(2)` => `mov edi,0x2`
-				int_lit := expr as ast.IntegerLiteral
-				g.mov(fn_arg_registers[i], int_lit.val.int())
+				g.mov(fn_arg_registers[i], it.val.int())
 			}
 			ast.Ident {
 				// `foo(x)` => `mov edi,DWORD PTR [rbp-0x8]`

vlib/v/parser/if.v

@@ -99,6 +99,11 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 	cond_pos := p.tok.position()
 	cond := p.expr(0)
 	p.inside_match = false
+	mut var_name := ''
+	if p.tok.kind == .key_as {
+		p.next()
+		var_name = p.check_name()
+	}
 	p.check(.lcbr)
 	mut branches := []ast.MatchBranch{}
 	for {
@@ -114,6 +119,20 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 		} else if p.tok.kind == .name && !(p.tok.lit == 'C' && p.peek_tok.kind == .dot) &&
 			(p.tok.lit in table.builtin_type_names || (p.tok.lit[0].is_capital() && !p.tok.lit.is_upper()) ||
 			p.peek_tok.kind == .dot) {
+			if var_name.len == 0 {
+				match cond {
+					ast.Ident {
+						// shadow match cond variable
+						var_name = it.name
+					}
+					// ast.SelectorExpr {
+					// 	p.error('expecting `as` (eg. `match user.attribute as user_attr`) when matching struct fields')
+					// }
+					else {
+						// p.error('only variables can be used in sum types matches')
+					}
+				}
+			}
 			// Sum type match
 			typ := p.parse_type()
 			exprs << ast.Type{
@@ -126,32 +145,23 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 				is_used: true
 				is_mut: is_mut
 			})
+			if var_name.len > 0 {
+				// Register shadow variable or `as` variable with actual type
+				p.scope.register(var_name, ast.Var{
+					name: var_name
+					typ: typ.to_ptr()
+					pos: cond_pos
+					is_used: true
+					is_mut: is_mut
+				})
+			}
 			// TODO
 			if p.tok.kind == .comma {
 				p.next()
 				p.parse_type()
 			}
 			is_sum_type = true
-			// Make sure a variable used for the sum type match
-			mut var_name := ''
-			match cond {
-				ast.Ident {
-					var_name = it.name
-				}
-				else {
-					// p.error('only variables can be used in sum types matches')
-				}
-			}
-			if var_name != '' {
-				// Register a shadow variable with the actual type
-				// (this replaces the old `it`)
-				// TODO doesn't work right now (fixed, uncomment when merging)
-				// p.scope.register(var_name, ast.Var{
-				// name: var_name
-				// typ: typ.to_ptr()
-				// })
-				// println(var_name)
-			}
+				
 		} else {
 			// Expression match
 			for {
@@ -200,5 +210,6 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 		is_sum_type: is_sum_type
 		pos: pos
 		is_mut: is_mut
+		var_name: var_name
 	}
 }

vlib/v/parser/pratt.v

@@ -166,6 +166,11 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 			node = p.index_expr(node)
 			p.is_stmt_ident = is_stmt_ident
 		} else if p.tok.kind == .key_as {
+			// sum type match `match x as alias` so return early
+			if p.inside_match {
+				return node
+			}
+			// sum type as cast `x := SumType as Variant`
 			pos := p.tok.position()
 			p.next()
 			typ = p.parse_type()