handle bitcast and construction expressions in the lowerer

Author: teoxoy

naga/src/front/wgsl/error.rs

@@ -199,6 +199,7 @@ pub(crate) enum Error<'a> {
     InvalidIdentifierUnderscore(Span),
     ReservedIdentifierPrefix(Span),
     UnknownAddressSpace(Span),
+    UnknownRayFlag(Span),
     RepeatedAttribute(Span),
     UnknownAttribute(Span),
     UnknownBuiltin(Span),
@@ -275,6 +276,7 @@ pub(crate) enum Error<'a> {
         span: Span,
     },
     CalledEntryPoint(Span),
+    CalledLocalDecl(Span),
     WrongArgumentCount {
         span: Span,
         expected: Range<u32>,
@@ -415,6 +417,12 @@ pub(crate) enum Error<'a> {
     UnexpectedIdentForEnumerant(Span),
     UnexpectedExprForEnumerant(Span),
     UnusedArgsForTemplate(Vec<Span>),
+    UnexpectedTemplate(Span),
+    MissingTemplateArg {
+        span: Span,
+        arg: &'static str,
+    },
+    UnexpectedExprForTypeExpression(Span),
 }
 
 impl From<ConflictingDiagnosticRuleError> for Error<'_> {
@@ -655,6 +663,11 @@ impl<'a> Error<'a> {
                 labels: vec![(bad_span, "unknown address space".into())],
                 notes: vec![],
             },
+            Error::UnknownRayFlag(bad_span) => ParseError {
+                message: format!("unknown ray flag: `{}`", &source[bad_span]),
+                labels: vec![(bad_span, "unknown ray flag".into())],
+                notes: vec![],
+            },
             Error::RepeatedAttribute(bad_span) => ParseError {
                 message: format!("repeated attribute: `{}`", &source[bad_span]),
                 labels: vec![(bad_span, "repeated attribute".into())],
@@ -914,6 +927,11 @@ impl<'a> Error<'a> {
                 labels: vec![(span, "entry point cannot be called".into())],
                 notes: vec![],
             },
+            Error::CalledLocalDecl(span) => ParseError {
+                message: "local declaration cannot be called".to_string(),
+                labels: vec![(span, "local declaration cannot be called".into())],
+                notes: vec![],
+            },
             Error::WrongArgumentCount {
                 span,
                 ref expected,
@@ -1402,6 +1420,27 @@ impl<'a> Error<'a> {
                 labels: expr_spans.iter().cloned().map(|span| -> (_, _){ (span, "unused".into()) }).collect(),
                 notes: vec![],
             },
+            Error::UnexpectedTemplate(span) => ParseError {
+                message: "unexpected template".to_string(),
+                labels: vec![(span, "expected identifier".into())],
+                notes: vec![],
+            },
+            Error::MissingTemplateArg {
+                span,
+                arg,
+            } => ParseError {
+                message: format!(
+                    "`{}` needs a template argument specified: {arg}",
+                    &source[span]
+                ),
+                labels: vec![(span, "is missing a template argument".into())],
+                notes: vec![],
+            },
+            Error::UnexpectedExprForTypeExpression(expr_span) => ParseError {
+                message: "unexpected expression".to_string(),
+                labels: vec![(expr_span, "needs to be an identifier resolving to a type declaration (alias or struct) or predeclared type(-generator)".into())],
+                notes: vec![],
+            }
         }
     }
 }

naga/src/front/wgsl/lower/construction.rs

@@ -1,10 +1,4 @@
-use alloc::{
-    boxed::Box,
-    format,
-    string::{String, ToString},
-    vec,
-    vec::Vec,
-};
+use alloc::{boxed::Box, vec, vec::Vec};
 use core::num::NonZeroU32;
 
 use crate::common::wgsl::TypeContext;
@@ -13,9 +7,22 @@ use crate::front::wgsl::parse::ast;
 use crate::front::wgsl::{Error, Result};
 use crate::{Handle, Span};
 
-/// A cooked form of `ast::ConstructorType` that uses Naga types whenever
-/// possible.
-enum Constructor<T> {
+/// A [`constructor built-in function`].
+///
+/// WGSL has two types of such functions:
+///
+/// - Those that fully specify the type being constructed, like
+///   `vec3<f32>(x,y,z)`, which obviously constructs a `vec3<f32>`.
+///
+/// - Those that leave the component type of the composite being constructed
+///   implicit, to be inferred from the argument types, like `vec3(x,y,z)`,
+///   which constructs a `vec3<T>` where `T` is the type of `x`, `y`, and `z`.
+///
+/// This enum represents both cases. The `PartialFoo` variants
+/// represent the second case, where the component type is implicit.
+///
+/// [`constructor built-in function`]: https://gpuweb.github.io/gpuweb/wgsl/#constructor-builtin-function
+pub enum Constructor<T> {
     /// A vector construction whose component type is inferred from the
     /// argument: `vec3(1.0)`.
     PartialVector { size: crate::VectorSize },
@@ -62,21 +69,6 @@ impl Constructor<Handle<crate::Type>> {
     }
 }
 
-impl Constructor<(Handle<crate::Type>, &crate::TypeInner)> {
-    fn to_error_string(&self, ctx: &ExpressionContext) -> String {
-        match *self {
-            Self::PartialVector { size } => {
-                format!("vec{}<?>", size as u32,)
-            }
-            Self::PartialMatrix { columns, rows } => {
-                format!("mat{}x{}<?>", columns as u32, rows as u32,)
-            }
-            Self::PartialArray => "array<?, ?>".to_string(),
-            Self::Type((handle, _inner)) => ctx.type_to_string(handle),
-        }
-    }
-}
-
 enum Components<'a> {
     None,
     One {
@@ -117,15 +109,13 @@ impl<'source> Lowerer<'source, '_> {
     pub fn construct(
         &mut self,
         span: Span,
-        constructor: &ast::ConstructorType<'source>,
+        constructor: Constructor<Handle<crate::Type>>,
         ty_span: Span,
         components: &[Handle<ast::Expression<'source>>],
         ctx: &mut ExpressionContext<'source, '_, '_>,
     ) -> Result<'source, Handle<crate::Expression>> {
         use crate::proc::TypeResolution as Tr;
 
-        let constructor_h = self.constructor(constructor, ctx)?;
-
         let components = match *components {
             [] => Components::None,
             [component] => {
@@ -160,7 +150,7 @@ impl<'source> Lowerer<'source, '_> {
         // Even though we computed `constructor` above, wait until now to borrow
         // a reference to the `TypeInner`, so that the component-handling code
         // above can have mutable access to the type arena.
-        let constructor = constructor_h.borrow_inner(ctx.module);
+        let constructor = constructor.borrow_inner(ctx.module);
 
         let expr;
         match (components, constructor) {
@@ -554,14 +544,19 @@ impl<'source> Lowerer<'source, '_> {
                 Components::One {
                     span, component, ..
                 },
-                constructor,
+                Constructor::Type((
+                    ty,
+                    &(crate::TypeInner::Scalar { .. }
+                    | crate::TypeInner::Vector { .. }
+                    | crate::TypeInner::Matrix { .. }),
+                )),
             ) => {
                 let component_ty = &ctx.typifier()[component];
                 let from_type = ctx.type_resolution_to_string(component_ty);
                 return Err(Box::new(Error::BadTypeCast {
                     span,
                     from_type,
-                    to_type: constructor.to_error_string(ctx),
+                    to_type: ctx.type_to_string(ty),
                 }));
             }
 
@@ -581,77 +576,4 @@ impl<'source> Lowerer<'source, '_> {
         let expr = ctx.append_expression(expr, span)?;
         Ok(expr)
     }
-
-    /// Build a [`Constructor`] for a WGSL construction expression.
-    ///
-    /// If `constructor` conveys enough information to determine which Naga [`Type`]
-    /// we're actually building (i.e., it's not a partial constructor), then
-    /// ensure the `Type` exists in [`ctx.module`], and return
-    /// [`Constructor::Type`].
-    ///
-    /// Otherwise, return the [`Constructor`] partial variant corresponding to
-    /// `constructor`.
-    ///
-    /// [`Type`]: crate::Type
-    /// [`ctx.module`]: ExpressionContext::module
-    fn constructor<'out>(
-        &mut self,
-        constructor: &ast::ConstructorType<'source>,
-        ctx: &mut ExpressionContext<'source, '_, 'out>,
-    ) -> Result<'source, Constructor<Handle<crate::Type>>> {
-        let handle = match *constructor {
-            ast::ConstructorType::Scalar(scalar) => {
-                let ty = ctx.ensure_type_exists(scalar.to_inner_scalar());
-                Constructor::Type(ty)
-            }
-            ast::ConstructorType::PartialVector { size } => Constructor::PartialVector { size },
-            ast::ConstructorType::Vector { size, ty, ty_span } => {
-                let ty = self.resolve_ast_type(ty, &mut ctx.as_const())?;
-                let scalar = match ctx.module.types[ty].inner {
-                    crate::TypeInner::Scalar(sc) => sc,
-                    _ => return Err(Box::new(Error::UnknownScalarType(ty_span))),
-                };
-                let ty = ctx.ensure_type_exists(crate::TypeInner::Vector { size, scalar });
-                Constructor::Type(ty)
-            }
-            ast::ConstructorType::PartialMatrix { columns, rows } => {
-                Constructor::PartialMatrix { columns, rows }
-            }
-            ast::ConstructorType::Matrix {
-                rows,
-                columns,
-                ty,
-                ty_span,
-            } => {
-                let ty = self.resolve_ast_type(ty, &mut ctx.as_const())?;
-                let scalar = match ctx.module.types[ty].inner {
-                    crate::TypeInner::Scalar(sc) => sc,
-                    _ => return Err(Box::new(Error::UnknownScalarType(ty_span))),
-                };
-                let ty = match scalar.kind {
-                    crate::ScalarKind::Float => ctx.ensure_type_exists(crate::TypeInner::Matrix {
-                        columns,
-                        rows,
-                        scalar,
-                    }),
-                    _ => return Err(Box::new(Error::BadMatrixScalarKind(ty_span, scalar))),
-                };
-                Constructor::Type(ty)
-            }
-            ast::ConstructorType::PartialArray => Constructor::PartialArray,
-            ast::ConstructorType::Array { base, size } => {
-                let base = self.resolve_ast_type(base, &mut ctx.as_const())?;
-                let size = self.array_size(size, &mut ctx.as_const())?;
-
-                ctx.layouter.update(ctx.module.to_ctx()).unwrap();
-                let stride = ctx.layouter[base].to_stride();
-
-                let ty = ctx.ensure_type_exists(crate::TypeInner::Array { base, size, stride });
-                Constructor::Type(ty)
-            }
-            ast::ConstructorType::Type(ty) => Constructor::Type(ty),
-        };
-
-        Ok(handle)
-    }
 }