checker,cgen: evaluate comptime $if results in checker *only* (fix #25123) (fix #25156) (#25150)

Author: kbkpbot

cmd/tools/vast/vast.v

@@ -1538,7 +1538,6 @@ fn (t Tree) if_branch(node ast.IfBranch) &Node {
 	obj.add_terse('cond', t.expr(node.cond))
 	obj.add('pos', t.pos(node.pos))
 	obj.add('body_pos', t.pos(node.body_pos))
-	obj.add_terse('pkg_exist', t.bool_node(node.pkg_exist))
 	obj.add_terse('stmts', t.array_node_stmt(node.stmts))
 	obj.add('scope', t.number_node(int(node.scope)))
 	obj.add('comments', t.array_node_comment(node.comments))

vlib/v/ast/ast.v

@@ -1234,10 +1234,9 @@ pub:
 	body_pos token.Pos
 	comments []Comment
 pub mut:
-	cond      Expr
-	pkg_exist bool
-	stmts     []Stmt
-	scope     &Scope = unsafe { nil }
+	cond  Expr
+	stmts []Stmt
+	scope &Scope = unsafe { nil }
 }
 
 pub struct UnsafeExpr {
@@ -2131,6 +2130,8 @@ pub fn (cc ComptimeCall) expr_str() string {
 		if arg.expr.is_pure_literal() {
 			str = "\$${cc.method_name}('${cc.args_var}', ${arg})"
 		}
+	} else if cc.kind == .pkgconfig {
+		str = "\$${cc.method_name}('${cc.args_var}')"
 	}
 	return str
 }

vlib/v/ast/table.v

@@ -94,6 +94,13 @@ pub mut:
 	anon_struct_counter int
 	anon_union_names    map[string]int // anon union name -> union sym idx
 	anon_union_counter  int
+	comptime_is_true    map[string]ComptTimeCondResult // The evaluate cond results for different generic types combination, such as `comptime_is_true['T=int,X=string|main.v|pos ...'] = {true, '!DEFINED(WINDOWS)'}`
+}
+
+pub struct ComptTimeCondResult {
+pub mut:
+	val   bool
+	c_str string
 }
 
 // used by vls to avoid leaks