[librsvg: 1/2] (#703): Ignore elements in an error state inside the <switch> element

[Federico Mena Quintero <federico src gnome org>]

commit 645b85f4de3ae2f8c2b5459fca6650218871261f
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Mar 29 18:08:07 2021 -0600

    (#703): Ignore elements in an error state inside the <switch> element
    
    It turns out that the implementation for <switch> needs to be aware of
    elements that have been set in an error state while parsing their
    attributes.  For example, getting an error while parsing
    `systemLanguage` for an element inside a <switch> should cause *that*
    element to be ignored while picking which of `<switch>`'s children to
    render.
    
    Fixes https://gitlab.gnome.org/GNOME/librsvg/-/issues/703

 src/structure.rs  |  9 ++++-----
 tests/src/bugs.rs | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 53 insertions(+), 6 deletions(-)
---
diff --git a/src/structure.rs b/src/structure.rs
index 185deba2..d783b5f5 100644
--- a/src/structure.rs
+++ b/src/structure.rs
@@ -68,11 +68,10 @@ impl Draw for Switch {
         let values = cascaded.get();
 
         draw_ctx.with_discrete_layer(node, acquired_nodes, values, clipping, &mut |an, dc| {
-            if let Some(child) = node
-                .children()
-                .filter(|c| c.is_element())
-                .find(|c| c.borrow_element().get_cond())
-            {
+            if let Some(child) = node.children().filter(|c| c.is_element()).find(|c| {
+                let elt = c.borrow_element();
+                elt.get_cond() && !elt.is_in_error()
+            }) {
                 child.draw(an, &CascadedValues::new(cascaded, &child), dc, clipping)
             } else {
                 Ok(dc.empty_bbox())
diff --git a/tests/src/bugs.rs b/tests/src/bugs.rs
index 320d364b..344a9503 100644
--- a/tests/src/bugs.rs
+++ b/tests/src/bugs.rs
@@ -7,7 +7,7 @@ use librsvg::{CairoRenderer, Loader, LoadingError, SvgHandle};
 use matches::matches;
 
 use crate::reference_utils::{Compare, Evaluate, Reference};
-use crate::utils::{load_svg, render_document, setup_font_map, SurfaceSize};
+use crate::utils::{load_svg, render_document, setup_font_map, setup_language, SurfaceSize};
 
 // https://gitlab.gnome.org/GNOME/librsvg/issues/335
 #[test]
@@ -354,3 +354,51 @@ fn test_text_bounds(name: &str) {
     // was not being computed correctly at all.
     assert!(ink_r.y > 48.0 && ink_r.y < 49.0);
 }
+
+// https://gitlab.gnome.org/GNOME/librsvg/-/issues/703
+#[test]
+fn switch_element_should_ignore_elements_in_error() {
+    setup_language();
+
+    let svg = load_svg(
+        br##"<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg"; width="100" height="100">
+  <switch>
+    <rect x="10" y="10" width="10" height="10" systemLanguage="es_MX" id="es" fill="red"/>
+    <rect x="10" y="10" width="10" height="10" id="no_lang" fill="blue"/>
+  </switch>
+</svg>
+"##,
+    )
+    .unwrap();
+
+    let output_surf = render_document(
+        &svg,
+        SurfaceSize(100, 100),
+        |_| (),
+        cairo::Rectangle {
+            x: 0.0,
+            y: 0.0,
+            width: 100.0,
+            height: 100.0,
+        },
+    )
+    .unwrap();
+
+    let reference_surf = cairo::ImageSurface::create(cairo::Format::ARgb32, 100, 100).unwrap();
+
+    {
+        let cr = cairo::Context::new(&reference_surf);
+
+        cr.rectangle(10.0, 10.0, 10.0, 10.0);
+        cr.set_source_rgba(0.0, 0.0, 1.0, 1.0);
+        cr.fill();
+    }
+
+    Reference::from_surface(reference_surf)
+        .compare(&output_surf)
+        .evaluate(
+            &output_surf,
+            "switch_element_should_ignore_elements_in_error",
+        );
+}