v.gen.c: fix error of if_expr in infix_expr (#11200)

vlib/v/gen/c/cgen.v

@@ -168,13 +168,14 @@ mut:
 	// TypeOne, TypeTwo {}
 	// where an aggregate (at least two types) is generated
 	// sum type deref needs to know which index to deref because unions take care of the correct field
-	aggregate_type_idx int
-	returned_var_name  string // to detect that a var doesn't need to be freed since it's being returned
-	branch_parent_pos  int    // used in BranchStmt (continue/break) for autofree stop position
-	timers             &util.Timers = util.new_timers(false)
-	force_main_console bool // true when [console] used on fn main()
-	as_cast_type_names map[string]string // table for type name lookup in runtime (for __as_cast)
-	obf_table          map[string]string
+	aggregate_type_idx  int
+	returned_var_name   string // to detect that a var doesn't need to be freed since it's being returned
+	branch_parent_pos   int    // used in BranchStmt (continue/break) for autofree stop position
+	infix_left_var_name string // a && if expr
+	timers              &util.Timers = util.new_timers(false)
+	force_main_console  bool // true when [console] used on fn main()
+	as_cast_type_names  map[string]string // table for type name lookup in runtime (for __as_cast)
+	obf_table           map[string]string
 	// main_fn_decl_node  ast.FnDecl
 	expected_cast_type ast.Type // for match expr of sumtypes
 	defer_vars         []string
@@ -4626,6 +4627,10 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
 		cur_line = g.go_before_stmt(0)
 		g.empty_line = true
 		g.writeln('$styp $tmp; /* if prepend */')
+		if g.infix_left_var_name.len > 0 {
+			g.writeln('if ($g.infix_left_var_name) {')
+			g.indent++
+		}
 	} else if node.is_expr || g.inside_ternary != 0 {
 		g.inside_ternary++
 		g.write('(')
@@ -4739,6 +4744,10 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
 	}
 	g.writeln('}')
 	if needs_tmp_var {
+		if g.infix_left_var_name.len > 0 {
+			g.indent--
+			g.writeln('}')
+		}
 		g.empty_line = false
 		g.write('$cur_line $tmp')
 	}

vlib/v/gen/c/infix_expr.v

@@ -33,6 +33,9 @@ fn (mut g Gen) infix_expr(node ast.InfixExpr) {
 		.left_shift {
 			g.infix_expr_left_shift_op(node)
 		}
+		.and, .logical_or {
+			g.infix_expr_and_or_op(node)
+		}
 		else {
 			// `x & y == 0` => `(x & y) == 0` in C
 			need_par := node.op in [.amp, .pipe, .xor]
@@ -499,28 +502,34 @@ fn (mut g Gen) infix_expr_left_shift_op(node ast.InfixExpr) {
 	}
 }
 
+// infix_expr_and_or_op generates code for `&&` and `||`
+fn (mut g Gen) infix_expr_and_or_op(node ast.InfixExpr) {
+	if node.right is ast.IfExpr {
+		// b := a && if true { a = false ...} else {...}
+		if g.need_tmp_var_in_if(node.right) {
+			tmp := g.new_tmp_var()
+			cur_line := g.go_before_stmt(0).trim_space()
+			g.empty_line = true
+			g.write('bool $tmp = (')
+			g.expr(node.left)
+			g.writeln(');')
+			g.stmt_path_pos << g.out.len
+			g.write('$cur_line $tmp $node.op.str() ')
+			g.infix_left_var_name = if node.op == .and { tmp } else { '!$tmp' }
+			g.expr(node.right)
+			g.infix_left_var_name = ''
+			return
+		}
+	}
+	g.gen_plain_infix_expr(node)
+}
+
 // gen_plain_infix_expr generates basic code for infix expressions,
 // without any overloading of any kind
 // i.e. v`a + 1` => c`a + 1`
 // It handles auto dereferencing of variables, as well as automatic casting
 // (see Gen.expr_with_cast for more details)
 fn (mut g Gen) gen_plain_infix_expr(node ast.InfixExpr) {
-	if node.left is ast.Ident && node.right is ast.IfExpr {
-		// b := a && if true { a = false ...} else {...}
-		if g.need_tmp_var_in_if(node.right) {
-			tmp := g.new_tmp_var()
-			styp := g.typ(node.left_type)
-			cur_line := g.go_before_stmt(0)
-			g.empty_line = true
-			g.write('$styp $tmp = ')
-			g.expr(node.left)
-			g.writeln(';')
-			g.stmt_path_pos << g.out.len
-			g.write('$cur_line $tmp $node.op.str() ')
-			g.expr(node.right)
-			return
-		}
-	}
 	if node.left_type.is_ptr() && node.left.is_auto_deref_var() {
 		g.write('*')
 	}

vlib/v/tests/valgrind/if_expr_skip.v

@@ -0,0 +1,13 @@
+fn main() {
+	mut a := false
+	b := a && if true {
+		a = true
+		true
+	} else {
+		false
+	}
+	println(b)
+	assert b == false
+	println(a)
+	assert a == false
+}