From f78478bea118583ea8f730a9e426f262f3f642fc Mon Sep 17 00:00:00 2001
From: James Westman <james@jwestman.net>
Date: Thu, 28 Apr 2022 22:42:09 -0500
Subject: [PATCH] validation: Writable/construct-only properties

Add two new errors, one for non-writable properties and another for
binding construct-only properties.
---
 blueprintcompiler/gir.py                       |  8 ++++++++
 blueprintcompiler/language/gobject_property.py | 15 ++++++++++++++-
 tests/sample_errors/read_only_properties.blp   |  6 ++++++
 tests/sample_errors/read_only_properties.err   |  2 ++
 tests/test_samples.py                          |  1 +
 5 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 tests/sample_errors/read_only_properties.blp
 create mode 100644 tests/sample_errors/read_only_properties.err

diff --git a/blueprintcompiler/gir.py b/blueprintcompiler/gir.py
index e30f04a..973ccbb 100644
--- a/blueprintcompiler/gir.py
+++ b/blueprintcompiler/gir.py
@@ -184,6 +184,14 @@ class Property(GirNode):
     def signature(self):
         return f"{self.type_name} {self.container.name}.{self.name}"
 
+    @property
+    def writable(self):
+        return self.xml["writable"] == "1"
+
+    @property
+    def construct_only(self):
+        return self.xml["construct-only"] == "1"
+
 
 class Parameter(GirNode):
     def __init__(self, container: GirNode, xml: xml_reader.Element):
diff --git a/blueprintcompiler/language/gobject_property.py b/blueprintcompiler/language/gobject_property.py
index 99e51fd..a542901 100644
--- a/blueprintcompiler/language/gobject_property.py
+++ b/blueprintcompiler/language/gobject_property.py
@@ -29,7 +29,7 @@ class Property(AstNode):
         Statement(
             UseIdent("name"),
             ":",
-            "bind",
+            Keyword("bind"),
             UseIdent("bind_source").expected("the ID of a source object to bind from"),
             ".",
             UseIdent("bind_property").expected("a property name to bind from"),
@@ -85,6 +85,19 @@ class Property(AstNode):
                 did_you_mean=(self.tokens["name"], self.gir_class.properties.keys())
             )
 
+    @validate("bind")
+    def property_bindable(self):
+        if self.tokens["bind"] and self.gir_property is not None and self.gir_property.construct_only:
+            raise CompileError(
+                f"{self.gir_property.full_name} can't be bound because it is construct-only",
+                hints=["construct-only properties may only be set to a static value"]
+            )
+
+    @validate("name")
+    def property_writable(self):
+        if self.gir_property is not None and not self.gir_property.writable:
+            raise CompileError(f"{self.gir_property.full_name} is not writable")
+
 
     @validate()
     def obj_property_type(self):
diff --git a/tests/sample_errors/read_only_properties.blp b/tests/sample_errors/read_only_properties.blp
new file mode 100644
index 0000000..0c0b5ca
--- /dev/null
+++ b/tests/sample_errors/read_only_properties.blp
@@ -0,0 +1,6 @@
+using Gtk 4.0;
+
+ComboBox combo_box {
+  has-entry: bind combo_box.visible;
+  scale-factor: 2;
+}
diff --git a/tests/sample_errors/read_only_properties.err b/tests/sample_errors/read_only_properties.err
new file mode 100644
index 0000000..dc03297
--- /dev/null
+++ b/tests/sample_errors/read_only_properties.err
@@ -0,0 +1,2 @@
+4,14,4,ComboBox.has-entry can't be bound because it is construct-only
+5,3,12,Widget.scale-factor is not writable
diff --git a/tests/test_samples.py b/tests/test_samples.py
index f077536..c490388 100644
--- a/tests/test_samples.py
+++ b/tests/test_samples.py
@@ -190,6 +190,7 @@ class TestSamples(unittest.TestCase):
         self.assert_sample_error("obj_in_string_list")
         self.assert_sample_error("obj_prop_type")
         self.assert_sample_error("property_dne")
+        self.assert_sample_error("read_only_properties")
         self.assert_sample_error("signal_dne")
         self.assert_sample_error("signal_object_dne")
         self.assert_sample_error("size_group_non_widget")