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parser: support parsing unsafe (as first token) as UnsafeExpr (#6032)
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1c886ad067
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@ -2075,7 +2075,7 @@ To mark potentially memory-unsafe operations, enclose them in an `unsafe` block:
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mut p := unsafe { &byte(malloc(2)) }
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p[0] = `h` // Error: pointer indexing is only allowed in `unsafe` blocks
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unsafe {
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p[0] = `h`
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p[0] = `h` // OK
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p[1] = `i`
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}
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p++ // Error: pointer arithmetic is only allowed in `unsafe` blocks
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@ -491,7 +491,7 @@ pub mut:
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pub struct UnsafeExpr {
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pub:
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stmts []Stmt
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expr Expr
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pos token.Position
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}
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@ -1082,6 +1082,15 @@ pub fn (expr Expr) is_lvalue() bool {
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return false
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}
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pub fn (expr Expr) is_expr() bool {
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match expr {
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IfExpr {return expr.is_expr}
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MatchExpr {return expr.is_expr}
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else {}
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}
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return true
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}
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pub fn (stmt Stmt) position() token.Position {
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match stmt {
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AssertStmt { return stmt.pos }
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@ -264,7 +264,7 @@ pub fn (x Expr) str() string {
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return '_likely_(${it.expr.str()})'
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}
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UnsafeExpr {
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return 'unsafe { $it.stmts.len stmts }'
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return 'unsafe { $it.expr }'
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}
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else {}
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}
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@ -3101,30 +3101,11 @@ pub fn (mut c Checker) lock_expr(mut node ast.LockExpr) table.Type {
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}
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pub fn (mut c Checker) unsafe_expr(mut node ast.UnsafeExpr) table.Type {
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slen := node.stmts.len
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if slen > 1 {
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c.error('FIXME: unsafe expression block should support multiple statements', node.pos)
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return table.none_type
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}
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if slen == 0 {
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c.error('unsafe expression does not yield an expression', node.pos)
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return table.none_type
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}
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assert !c.inside_unsafe
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c.inside_unsafe = true
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defer {
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c.inside_unsafe = false
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}
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if slen > 1 {
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c.stmts(node.stmts[0..slen - 1])
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}
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last := node.stmts[0]
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if last is ast.ExprStmt {
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t := c.expr(last.expr)
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return t
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}
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c.error('unsafe expression does not yield an expression', node.pos)
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return table.none_type
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t := c.expr(node.expr)
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c.inside_unsafe = false
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return t
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}
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pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
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@ -1075,8 +1075,7 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
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}
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ast.UnsafeExpr {
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f.write('unsafe {')
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es := node.stmts[0] as ast.ExprStmt
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f.expr(es.expr)
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f.expr(node.expr)
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f.write('}')
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}
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}
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@ -2224,8 +2224,7 @@ fn (mut g Gen) expr(node ast.Expr) {
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g.write(')')
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}
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ast.UnsafeExpr {
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es := node.stmts[0] as ast.ExprStmt
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g.expr(es.expr)
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g.expr(node.expr)
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}
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}
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}
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@ -655,8 +655,7 @@ fn (mut g JsGen) expr(node ast.Expr) {
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// TODO
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}
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ast.UnsafeExpr {
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es := node.stmts[0] as ast.ExprStmt
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g.expr(es.expr)
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g.expr(node.expr)
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}
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}
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}
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@ -623,27 +623,7 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
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}
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}
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.key_unsafe {
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if p.peek_tok.kind == .lcbr {
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// unsafe {
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p.next()
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assert !p.inside_unsafe
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p.inside_unsafe = true
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stmts := p.parse_block()
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p.inside_unsafe = false
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return ast.Block{
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stmts: stmts
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is_unsafe: true
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}
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} else {
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p.error_with_pos('please use `unsafe {`', p.tok.position())
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}
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// unsafe( ; NB: this will be never reached
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pos := p.tok.position()
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ex := p.expr(0)
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return ast.ExprStmt{
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expr: ex
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pos: pos
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}
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return p.unsafe_stmt()
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}
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.hash {
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return p.hash()
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@ -1988,3 +1968,55 @@ pub fn (mut p Parser) mark_var_as_used(varname string) bool {
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}
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return false
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}
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fn (mut p Parser) unsafe_stmt() ast.Stmt {
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pos := p.tok.position()
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p.next()
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if p.tok.kind != .lcbr {
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p.error_with_pos('please use `unsafe {`', p.tok.position())
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}
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p.next()
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assert !p.inside_unsafe
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if p.tok.kind == .rcbr {
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// `unsafe {}`
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p.next()
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return ast.Block{
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is_unsafe: true
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}
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}
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p.inside_unsafe = true
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p.open_scope() // needed in case of `unsafe {stmt}`
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defer {
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p.inside_unsafe = false
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p.close_scope()
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}
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stmt := p.stmt(false)
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if p.tok.kind == .rcbr {
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if stmt is ast.ExprStmt {
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// `unsafe {expr}`
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if stmt.expr.is_expr() {
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p.next()
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ue := ast.UnsafeExpr{
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expr: stmt.expr
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pos: pos
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}
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// parse e.g. `unsafe {expr}.foo()`
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expr := p.expr_with_left(ue, 0, p.is_stmt_ident)
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return ast.ExprStmt{
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expr: expr
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pos: pos
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}
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}
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}
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}
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// unsafe {stmts}
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mut stmts := [stmt]
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for p.tok.kind != .rcbr {
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stmts << p.stmt(false)
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}
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p.next()
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return ast.Block{
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stmts: stmts
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is_unsafe: true
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}
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}
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@ -13,7 +13,6 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
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eprintln('parsing file: ${p.file_name:-30} | tok.kind: ${p.tok.kind:-10} | tok.lit: ${p.tok.lit:-10} | tok_pos: ${tok_pos.str():-45} | expr($precedence)')
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}
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// println('\n\nparser.expr()')
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mut typ := table.void_type
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mut node := ast.Expr{}
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is_stmt_ident := p.is_stmt_ident
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p.is_stmt_ident = false
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@ -96,16 +95,18 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
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node = p.if_expr(false)
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}
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.key_unsafe {
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// unsafe {
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p.next()
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pos := p.tok.position()
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assert !p.inside_unsafe
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p.inside_unsafe = true
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stmts := p.parse_block()
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p.inside_unsafe = false
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p.check(.lcbr)
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node = ast.UnsafeExpr{
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stmts: stmts
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expr: p.expr(0)
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pos: pos
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}
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p.check(.rcbr)
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p.inside_unsafe = false
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}
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.key_lock, .key_rlock {
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node = p.lock_expr()
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@ -228,6 +229,11 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
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p.error('expr(): bad token `$p.tok.kind.str()`')
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}
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}
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return p.expr_with_left(node, precedence, is_stmt_ident)
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}
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pub fn (mut p Parser) expr_with_left(left ast.Expr, precedence int, is_stmt_ident bool) ast.Expr {
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mut node := left
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// Infix
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for precedence < p.tok.precedence() {
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if p.tok.kind == .dot {
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@ -244,7 +250,7 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
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// sum type as cast `x := SumType as Variant`
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pos := p.tok.position()
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p.next()
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typ = p.parse_type()
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typ := p.parse_type()
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node = ast.AsCast{
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expr: node
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typ: typ
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@ -3,17 +3,9 @@ fn test_ptr_assign() {
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mut p := &v[0]
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unsafe {
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(*p)++
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}
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unsafe {
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p++
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} // p now points to v[1]
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unsafe {
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p++ // p now points to v[1]
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(*p) += 2
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}
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unsafe {
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p += 2
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} // p now points to v[3]
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unsafe {
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p += 2 // p now points to v[3]
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*p = 31
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}
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assert v[0] == 6
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@ -26,8 +18,7 @@ fn test_ptr_infix() {
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v := 4
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mut q := unsafe {&v - 1}
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q = unsafe {q + 3}
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_ := q
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_ := v
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assert q == unsafe {&v + 2}
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}
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struct S1 {
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@ -44,3 +35,22 @@ fn test_funcs() {
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}
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_ = C.strerror(0) // [trusted] function prototype in builtin/cfns.c.v
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}
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fn test_if_expr_unsafe() {
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i := 4
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p := if true {
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unsafe {&i}
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}
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else {unsafe {&i}}
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assert *p == 4
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}
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fn test_unsafe_if_stmt() int {
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i := 4
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unsafe {
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if true {
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return (&i)[0]
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}
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}
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return i
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}
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