Two things #2253 costs an exported application, both found by decompiling
one that was built from published source.
StartupUri is written in App.xaml but never reaches the BAML: the markup
compiler turns the attribute into an assignment inside
InitializeComponent, and the project decompiler deletes the generated
members. The exported application then builds and opens no window. The
assignment is read back out of the generated method and written to the
document root again. Where the compiler emits no app.baml at all -
App.xaml carrying nothing but attributes - there is no document to write
it on, and the export has no ApplicationDefinition either; that is a
larger gap of its own.
x:Name is recorded as the runtime name property of an element, which is
FrameworkElement.Name for everything WPF - a property of the framework.
Any property called "Name" on a type of the assembly being decompiled was
written back as the directive, so <local:Helper Name="theName" /> came
back as x:Name: the name gets registered and the property stays unset,
which still compiles and quietly means something else. The directive is
now written only for a name the element does not declare itself.
Assisted-by: Claude:claude-opus-5:Claude Code
Obfuscators put arbitrary characters into BAML strings, and XML 1.0 has no
representation for most control characters - a numeric character reference is invalid
for them too. Writing such a document threw ArgumentException from XmlWriter, which
loses the resource on project export and shows an exception instead of the page in the
UI. The escapes are spelled the way the C# output spells them, so one convention covers
both languages. Namespace URIs have to be escaped where the XNamespace is created rather
than in the final pass: the URI is baked into every element name built from it, so
patching only the xmlns declaration would desync the two. Characters XML can carry stay
untouched, so ordinary documents decompile byte-identically.
Every BAML stream of an assembly lives in one .resources container, and the recovery
around resource writing sat outside the loop over its entries, so a single page that
could not be written discarded every other page sharing the container with it.
Assisted-by: Claude:claude-opus-5:Claude Code
Siegfried Pammer
ElektroKill
Peter Crabtree
Christoph Wille