From 0945889dd7244adbcfdc8b2e66a354e590683ef4 Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Mon, 15 Mar 2021 10:25:10 -0400
Subject: [PATCH] [msl] filter out entry points based on the bindings

---
 src/back/msl/mod.rs    | 18 ++++++++++++------
 src/back/msl/writer.rs | 25 +++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/src/back/msl/mod.rs b/src/back/msl/mod.rs
index f95ff8f3c9..177a945967 100644
--- a/src/back/msl/mod.rs
+++ b/src/back/msl/mod.rs
@@ -73,8 +73,6 @@ pub enum Error {
     Utf8(#[from] FromUtf8Error),
     #[error(transparent)]
     Type(#[from] TypifyError),
-    #[error("bind source for {0:?} is missing from the map")]
-    MissingBindTarget(BindSource),
     #[error("bind target {0:?} is empty")]
     UnimplementedBindTarget(BindTarget),
     #[error("composing of {0:?} is not implemented yet")]
@@ -89,6 +87,12 @@ pub enum Error {
     Validation,
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum EntryPointError {
+    #[error("bind source for {0:?} is missing from the map")]
+    MissingBinding(BindSource),
+}
+
 #[derive(Clone, Copy, Debug)]
 enum LocationMode {
     VertexInput,
@@ -154,7 +158,7 @@ impl Options {
         &self,
         stage: crate::ShaderStage,
         res_binding: &crate::ResourceBinding,
-    ) -> Result<ResolvedBinding, Error> {
+    ) -> Result<ResolvedBinding, EntryPointError> {
         let source = BindSource {
             stage,
             group: res_binding.group,
@@ -166,7 +170,7 @@ impl Options {
                 prefix: "fake",
                 index: 0,
             }),
-            None => Err(Error::MissingBindTarget(source)),
+            None => Err(EntryPointError::MissingBinding(source)),
         }
     }
 }
@@ -232,8 +236,10 @@ impl ResolvedBinding {
 /// for the use of the result.
 pub struct TranslationInfo {
     /// Mapping of the entry point names. Each item in the array
-    /// corresponds to an entry point in `module.entry_points.iter()`.
-    pub entry_point_names: Vec<String>,
+    /// corresponds to an entry point index.
+    ///
+    ///Note: Some entry points may fail translation because of missing bindings.
+    pub entry_point_names: Vec<Result<String, EntryPointError>>,
 }
 
 pub fn write_string(
diff --git a/src/back/msl/writer.rs b/src/back/msl/writer.rs
index 39d3e1e19c..97e563fc2d 100644
--- a/src/back/msl/writer.rs
+++ b/src/back/msl/writer.rs
@@ -1179,6 +1179,27 @@ impl<W: Write> Writer<W> {
         for (ep_index, ep) in module.entry_points.iter().enumerate() {
             let fun = &ep.function;
             let fun_info = analysis.get_entry_point(ep_index);
+            // skip this entry point if any global bindings are missing
+            if !options.fake_missing_bindings {
+                if let Some(err) = module
+                    .global_variables
+                    .iter()
+                    .find_map(|(var_handle, var)| {
+                        if !fun_info[var_handle].is_empty() {
+                            if let Some(ref br) = var.binding {
+                                if let Err(e) = options.resolve_global_binding(ep.stage, br) {
+                                    return Some(e);
+                                }
+                            }
+                        }
+                        None
+                    })
+                {
+                    info.entry_point_names.push(Err(err));
+                    continue;
+                }
+            }
+
             self.typifier.resolve_all(
                 &fun.expressions,
                 &module.types,
@@ -1192,7 +1213,7 @@ impl<W: Write> Writer<W> {
             )?;
 
             let fun_name = &self.names[&NameKey::EntryPoint(ep_index as _)];
-            info.entry_point_names.push(fun_name.clone());
+            info.entry_point_names.push(Ok(fun_name.clone()));
 
             let stage_out_name = format!("{}Output", fun_name);
             let stage_in_name = format!("{}Input", fun_name);
@@ -1340,7 +1361,7 @@ impl<W: Write> Writer<W> {
                 write!(self.out, "{} ", separator)?;
                 tyvar.try_fmt(&mut self.out)?;
                 if let Some(ref binding) = var.binding {
-                    let resolved = options.resolve_global_binding(ep.stage, binding)?;
+                    let resolved = options.resolve_global_binding(ep.stage, binding).unwrap();
                     resolved.try_fmt_decorated(&mut self.out, "")?;
                 }
                 if let Some(value) = var.init {