From a9c476d58d7d3bb896569f6d0b143d3034fe2949 Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Tue, 3 Mar 2020 14:09:41 -0500
Subject: [PATCH] Move out Void from the type enum

---
 src/back/msl.rs    | 11 +++++++----
 src/front/spirv.rs | 21 +++++++++------------
 src/front/wgsl.rs  |  7 ++-----
 src/lib.rs         |  3 +--
 4 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/src/back/msl.rs b/src/back/msl.rs
index f1246456cf..956dfddaff 100644
--- a/src/back/msl.rs
+++ b/src/back/msl.rs
@@ -452,9 +452,6 @@ impl<W: Write> Writer<W> {
         for (token, ty) in module.types.iter() {
             let name = ty.name.or_index(token);
             match ty.inner {
-                crate::TypeInner::Void => {
-                    write!(self.out, "typedef void {}", name)?;
-                },
                 crate::TypeInner::Scalar { kind, .. } => {
                     write!(self.out, "typedef {} {}", scalar_kind_string(kind), name)?;
                 },
@@ -600,7 +597,13 @@ impl<W: Write> Writer<W> {
                 writeln!(self.out, "{} {} {}(", em_str, output_name, fun_name)?;
                 writeln!(self.out, "\t{} {} [[stage_in]],", input_name, NAME_INPUT)?;
             } else {
-                let result_type_name = module.types[fun.return_type].name.or_index(fun.return_type);
+                let result_type_name = match fun.return_type {
+                    Some(type_id) => module.types[type_id].name.or_index(type_id),
+                    None => Name {
+                        class: "",
+                        source: NameSource::Custom { name: "void", prefix: false },
+                    },
+                };
                 writeln!(self.out, "{} {}(", result_type_name, fun_name)?;
                 for (index, &ty) in fun.parameter_types.iter().enumerate() {
                     let name = Name::from(ParameterIndex(index));
diff --git a/src/front/spirv.rs b/src/front/spirv.rs
index 65a13feece..020b63188d 100644
--- a/src/front/spirv.rs
+++ b/src/front/spirv.rs
@@ -12,7 +12,7 @@ TODO: would be nice to find ways that avoid looking up as much
 
 use crate::{
     storage::{Storage, Token},
-    FastHashMap,
+    FastHashMap, FastHashSet,
 };
 
 use std::convert::TryInto;
@@ -233,6 +233,7 @@ pub struct Parser<I> {
     future_member_decor: FastHashMap<(spirv::Word, MemberIndex), Decoration>,
     lookup_member_type_id: FastHashMap<(spirv::Word, MemberIndex), spirv::Word>,
     lookup_type: FastHashMap<spirv::Word, LookupType>,
+    lookup_void_type: FastHashSet<spirv::Word>,
     lookup_constant: FastHashMap<spirv::Word, LookupConstant>,
     lookup_variable: FastHashMap<spirv::Word, LookupVariable>,
     lookup_expression: FastHashMap<spirv::Word, LookupExpression>,
@@ -251,6 +252,7 @@ impl<I: Iterator<Item = u32>> Parser<I> {
             future_member_decor: FastHashMap::default(),
             lookup_member_type_id: FastHashMap::default(),
             lookup_type: FastHashMap::default(),
+            lookup_void_type: FastHashSet::default(),
             lookup_constant: FastHashMap::default(),
             lookup_variable: FastHashMap::default(),
             lookup_expression: FastHashMap::default(),
@@ -842,16 +844,7 @@ impl<I: Iterator<Item = u32>> Parser<I> {
                     self.switch(ModuleState::Type, inst.op)?;
                     inst.expect(2)?;
                     let id = self.next()?;
-                    let inner = crate::TypeInner::Void;
-                    self.lookup_type.insert(id, LookupType {
-                        token: module.types.append(crate::Type {
-                            name: self.future_decor
-                                .remove(&id)
-                                .and_then(|dec| dec.name),
-                            inner,
-                        }),
-                        base_id: None,
-                    });
+                    self.lookup_void_type.insert(id);
                 }
                 Op::TypeInt => {
                     self.switch(ModuleState::Type, inst.op)?;
@@ -1272,7 +1265,11 @@ impl<I: Iterator<Item = u32>> Parser<I> {
                             control: spirv::FunctionControl::from_bits(fun_control)
                                 .ok_or(Error::UnsupportedFunctionControl(fun_control))?,
                             parameter_types: Vec::with_capacity(ft.parameter_type_ids.len()),
-                            return_type: self.lookup_type.lookup(result_type)?.token,
+                            return_type: if self.lookup_void_type.contains(&result_type) {
+                                None
+                            } else {
+                                Some(self.lookup_type.lookup(result_type)?.token)
+                            },
                             expressions: self.make_expression_storage(),
                             body: Vec::new(),
                         }
diff --git a/src/front/wgsl.rs b/src/front/wgsl.rs
index 0f2e2c5f8b..d08a59dd85 100644
--- a/src/front/wgsl.rs
+++ b/src/front/wgsl.rs
@@ -179,12 +179,9 @@ impl Parser {
             control: spirv::FunctionControl::empty(),
             parameter_types: Vec::new(),
             return_type: if function_type_decl.as_rule() == Rule::type_decl {
-                self.parse_type_decl(function_type_decl, &mut module.types)?
+                Some(self.parse_type_decl(function_type_decl, &mut module.types)?)
             } else {
-                module.types.append(crate::Type {
-                    name: None,
-                    inner: crate::TypeInner::Void,
-                })
+                None
             },
             expressions: Storage::new(),
             body: Vec::new(),
diff --git a/src/lib.rs b/src/lib.rs
index 902a0b311c..579e29dbd7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -72,7 +72,6 @@ pub struct Type {
 
 #[derive(Debug, PartialEq)]
 pub enum TypeInner {
-    Void,
     Scalar { kind: ScalarKind, width: Bytes },
     Vector { size: VectorSize, kind: ScalarKind, width: Bytes },
     Matrix { columns: VectorSize, rows: VectorSize, kind: ScalarKind, width: Bytes },
@@ -172,7 +171,7 @@ pub struct Function {
     pub name: Option<String>,
     pub control: spirv::FunctionControl,
     pub parameter_types: Vec<Token<Type>>,
-    pub return_type: Token<Type>,
+    pub return_type: Option<Token<Type>>,
     pub expressions: Storage<Expression>,
     pub body: Block,
 }