Do not emit a "type annotations needed" error on include_bytes!() where the array length cannot be inferred

Author: ChayimFriedman2

crates/hir-def/src/expr_store.rs

@@ -795,6 +795,7 @@ impl ExpressionStore {
                 visitor.on_pat(target);
                 visitor.on_expr(value);
             }
+            Expr::IncludeBytes => {}
         }
     }
 

crates/hir-def/src/expr_store/lower.rs

@@ -1748,6 +1748,7 @@ impl<'db> ExprCollector<'db> {
                 self.alloc_expr(Expr::OffsetOf(OffsetOf { container, fields }), syntax_ptr)
             }
             ast::Expr::FormatArgsExpr(f) => self.collect_format_args(f, syntax_ptr),
+            ast::Expr::IncludeBytesExpr(_) => self.alloc_expr(Expr::IncludeBytes, syntax_ptr)
         })
     }
 

crates/hir-def/src/expr_store/pretty.rs

@@ -537,6 +537,7 @@ impl Printer<'_> {
             Expr::Missing => w!(self, "�"),
             Expr::Underscore => w!(self, "_"),
             Expr::InlineAsm(_) => w!(self, "builtin#asm(_)"),
+            Expr::IncludeBytes => w!(self, "include_bytes!(_)"),
             Expr::OffsetOf(offset_of) => {
                 w!(self, "builtin#offset_of(");
                 self.print_type_ref(offset_of.container);

crates/hir-def/src/hir.rs

@@ -323,6 +323,7 @@ pub enum Expr {
     Underscore,
     OffsetOf(OffsetOf),
     InlineAsm(InlineAsm),
+    IncludeBytes,
 }
 
 impl Expr {
@@ -344,7 +345,8 @@ impl Expr {
             | Expr::RecordLit { .. }
             | Expr::Tuple { .. }
             | Expr::OffsetOf(_)
-            | Expr::Underscore => ExprPrecedence::Unambiguous,
+            | Expr::Underscore
+            | Expr::IncludeBytes => ExprPrecedence::Unambiguous,
 
             Expr::Await { .. }
             | Expr::Call { .. }

crates/hir-expand/src/builtin/fn_macro.rs

@@ -852,17 +852,9 @@ fn include_bytes_expand(
     span: Span,
 ) -> ExpandResult<tt::TopSubtree> {
     // FIXME: actually read the file here if the user asked for macro expansion
-    let underscore = sym::underscore;
-    let zero = tt::Literal {
-        text_and_suffix: sym::_0_u8,
-        span,
-        kind: tt::LitKind::Integer,
-        suffix_len: 3,
-    };
-    // We don't use a real length since we can't know the file length, so we use an underscore
-    // to infer it.
+    let pound = mk_pound(span);
     let res = quote! {span =>
-        &[#zero; #underscore]
+        builtin #pound include_bytes
     };
     ExpandResult::ok(res)
 }

crates/hir-ty/src/infer/closure/analysis/expr_use_visitor.rs

@@ -692,6 +692,8 @@ impl<'a, 'b, 'db, D: Delegate<'db>> ExprUseVisitor<'a, 'b, 'db, D> {
                     self.consume_expr(rhs)?;
                 }
             }
+
+            Expr::IncludeBytes => {}
         }
         Ok(())
     }

crates/hir-ty/src/infer/expr.rs

@@ -269,7 +269,8 @@ impl<'db> InferenceContext<'_, 'db> {
             | Expr::Box { .. }
             | Expr::RecordLit { .. }
             | Expr::Yeet { .. }
-            | Expr::Missing => false,
+            | Expr::Missing
+            | Expr::IncludeBytes => false,
         }
     }
 
@@ -893,6 +894,11 @@ impl<'db> InferenceContext<'_, 'db> {
                     self.types.types.unit
                 }
             }
+            Expr::IncludeBytes => {
+                let len = self.table.next_const_var(Span::Dummy);
+                let arr = Ty::new_array_with_const_len(self.interner(), self.types.types.u8, len);
+                Ty::new_ref(self.interner(), self.types.regions.statik, arr, Mutability::Not)
+            }
         };
         let ty = self.insert_type_vars_shallow(ty);
         self.write_expr_ty(tgt_expr, ty);

crates/hir-ty/src/infer/mutability.rs

@@ -197,7 +197,8 @@ impl<'db> InferenceContext<'_, 'db> {
             | Expr::Literal(_)
             | Expr::Path(_)
             | Expr::Continue { .. }
-            | Expr::Underscore => (),
+            | Expr::Underscore
+            | Expr::IncludeBytes => (),
         }
     }
 

crates/hir-ty/src/mir/lower.rs

@@ -1397,6 +1397,7 @@ impl<'a, 'db> MirLowerCtx<'a, 'db> {
                 Ok(Some(current))
             }
             Expr::Underscore => Ok(Some(current)),
+            Expr::IncludeBytes => not_supported!("include_bytes!()"),
         }
     }
 

crates/ide-db/src/syntax_helpers/node_ext.rs

@@ -364,7 +364,8 @@ pub fn for_each_tail_expr(expr: &ast::Expr, cb: &mut dyn FnMut(&ast::Expr)) {
         | ast::Expr::YeetExpr(_)
         | ast::Expr::OffsetOfExpr(_)
         | ast::Expr::FormatArgsExpr(_)
-        | ast::Expr::AsmExpr(_) => cb(expr),
+        | ast::Expr::AsmExpr(_)
+        | ast::Expr::IncludeBytesExpr(_) => cb(expr),
     }
 }