From 396dca7f484d4d0e57372a74bbfee7c65afc7e83 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@vlang.io>
Date: Sun, 18 Oct 2020 21:22:37 +0200
Subject: [PATCH] checker: handle bad `$if` values

---
 vlib/gg/gg.v             |  5 ++++-
 vlib/v/checker/checker.v | 13 +++++++------
 vlib/v/gen/cgen.v        |  3 ++-
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/vlib/gg/gg.v b/vlib/gg/gg.v
index 15ac9f680c..6e97ade4f1 100644
--- a/vlib/gg/gg.v
+++ b/vlib/gg/gg.v
@@ -308,7 +308,10 @@ pub fn (ctx &Context) draw_circle_line(x f32, y f32, r int, segments int, c gx.C
 	sgl.end()
 }
 
-pub fn (ctx &Context) draw_circle(x f32, y f32, r int, segments int, c gx.Color) {
+pub fn (ctx &Context) draw_circle(x f32, y f32, r int, c gx.Color) {
+	ctx.draw_circle_with_segments(x,y,r,10, c)
+}
+pub fn (ctx &Context) draw_circle_with_segments(x f32, y f32, r int, segments int, c gx.Color) {
 	if c.a != 255 {
 		sgl.load_pipeline(ctx.timage_pip)
 	}
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 606c5f8547..c79361695b 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -3352,8 +3352,7 @@ pub fn (mut c Checker) unsafe_expr(mut node ast.UnsafeExpr) table.Type {
 }
 
 pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
-	is_ct := node.is_comptime
-	if_kind := if is_ct { '\$if' } else { 'if' }
+	if_kind := if node.is_comptime { '\$if' } else { 'if' }
 	expr_required := c.expected_type != table.void_type
 	former_expected_type := c.expected_type
 	node.typ = table.void_type
@@ -3368,7 +3367,7 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
 				branch.pos)
 		}
 		if !node.has_else || i < node.branches.len - 1 {
-			if is_ct {
+			if node.is_comptime {
 				should_skip = c.comp_if_branch(branch.cond, branch.pos)
 			} else {
 				// check condition type is boolean
@@ -3384,7 +3383,7 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
 			}
 		}
 		// smartcast sumtypes and interfaces when using `is`
-		if !is_ct && branch.cond is ast.InfixExpr {
+		if !node.is_comptime && branch.cond is ast.InfixExpr {
 			infix := branch.cond as ast.InfixExpr
 			if infix.op == .key_is {
 				right_expr := infix.right as ast.Type
@@ -3431,7 +3430,7 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
 				}
 			}
 		}
-		if is_ct { // Skip checking if needed
+		if node.is_comptime { // Skip checking if needed
 			cur_skip_flags := c.skip_flags
 			if found_branch {
 				c.skip_flags = true
@@ -3524,7 +3523,7 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
 	}
 	if expr_required {
 		if !node.has_else {
-			d := if is_ct { '$' } else { '' }
+			d := if node.is_comptime { '$' } else { '' }
 			c.error('`$if_kind` expression needs `${d}else` clause', node.pos)
 		}
 		return node.typ
@@ -3604,6 +3603,8 @@ fn (mut c Checker) comp_if_branch(cond ast.Expr, pos token.Position) bool {
 					'no_bounds_checking' { return cond.name !in c.pref.compile_defines_all }
 					else { return false }
 				}
+			} else {
+				c.error('unknown \$if value', pos)
 			}
 		}
 		else {
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 1a0e747e43..e1720e650a 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -724,6 +724,7 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) {
 	}
 	for i, stmt in stmts {
 		if i == stmts.len - 1 && tmp_var != '' {
+			// Handle if expressions, set the value of the last expression to the temp var.
 			g.write('$tmp_var = ')
 		}
 		g.stmt(stmt)
@@ -4938,7 +4939,7 @@ fn (mut g Gen) comp_if_to_ifdef(name string, is_comptime_optional bool) string {
 				(g.pref.compile_defines_all.len > 0 && name in g.pref.compile_defines_all) {
 				return 'CUSTOM_DEFINE_$name'
 			}
-			verror('bad os ifdef name "$name"')
+			verror('bad os ifdef name "$name"') // should never happen, caught in the checker
 		}
 	}
 	// verror('bad os ifdef name "$name"')