From a56361732e6632780170ba169988ea1195256905 Mon Sep 17 00:00:00 2001
From: Ashy <tarborhq@hotmail.com>
Date: Sun, 23 Oct 2022 20:00:57 +0100
Subject: [PATCH] Improved macro check

Reduced odds of making a mistake while reporting deactivated dynamic field features.
Also added feature flags to tests.
---
 crates/rune-macros/Cargo.toml     |  3 +++
 crates/rune-macros/src/any.rs     | 12 +----------
 crates/rune-macros/src/context.rs | 36 ++++++++++++++++++++++++++++---
 crates/rune/Cargo.toml            |  2 +-
 tests/Cargo.toml                  |  3 +--
 5 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/crates/rune-macros/Cargo.toml b/crates/rune-macros/Cargo.toml
index 1a340ad0b..1f2bc19f7 100644
--- a/crates/rune-macros/Cargo.toml
+++ b/crates/rune-macros/Cargo.toml
@@ -14,6 +14,9 @@ description = """
 Helper macros for Rune.
 """
 
+[features]
+dynamic_fields = []
+
 [dependencies]
 syn = { version = "1.0.82", features = ["full"] }
 quote = "1.0.10"
diff --git a/crates/rune-macros/src/any.rs b/crates/rune-macros/src/any.rs
index e971b558b..ca874e488 100644
--- a/crates/rune-macros/src/any.rs
+++ b/crates/rune-macros/src/any.rs
@@ -100,17 +100,7 @@ impl Derive {
 
         let meta_fields = match attrs.meta_fields {
             Some(meta_fields) => {
-                if cfg!(feature = "dynamic_fields") {
-                    quote! {#meta_fields}
-                } else {
-                    return Err(vec![syn::Error::new(
-                        meta_fields.span(),
-                        format!(
-                            "attempted to set dynamic_fields to `{}` while the feature `dynamic_fields` is disabled.",
-                            meta_fields
-                        ),
-                    )]);
-                }
+                quote! {#meta_fields}
             }
             None => quote! {Never},
         };
diff --git a/crates/rune-macros/src/context.rs b/crates/rune-macros/src/context.rs
index ca8a0832f..f4e9b504c 100644
--- a/crates/rune-macros/src/context.rs
+++ b/crates/rune-macros/src/context.rs
@@ -504,9 +504,39 @@ impl Context {
                     })) if path == DYNAMIC_FIELDS => {
                         attrs.meta_fields = Some(match s.value().as_str() {
                             "never" => format_ident!("Never"),
-                            "only" => format_ident!("Only"),
-                            "first" => format_ident!("First"),
-                            "last" => format_ident!("Last"),
+                            "only" => {
+                                if cfg!(feature = "dynamic_fields") {
+                                    format_ident!("Only")
+                                } else {
+                                    self.errors.push(syn::Error::new_spanned(
+                                s,
+                                "attempted to set dynamic_fields to `only` while the feature `dynamic_fields` is disabled."
+                            ));
+                                    return None;
+                                }
+                            }
+                            "first" => {
+                                if cfg!(feature = "dynamic_fields") {
+                                    format_ident!("First")
+                                } else {
+                                    self.errors.push(syn::Error::new_spanned(
+                                s,
+                                    "attempted to set dynamic_fields to `first` while the feature `dynamic_fields` is disabled."
+                            ));
+                                    return None;
+                                }
+                            }
+                            "last" => {
+                                if cfg!(feature = "dynamic_fields") {
+                                    format_ident!("Last")
+                                } else {
+                                    self.errors.push(syn::Error::new_spanned(
+                                s,
+                                    "attempted to set dynamic_fields to `last` while the feature `dynamic_fields` is disabled."
+                            ));
+                                    return None;
+                                }
+                            }
                             _ => {
                                 self.errors.push(syn::Error::new_spanned(
                                     s,
diff --git a/crates/rune/Cargo.toml b/crates/rune/Cargo.toml
index e66551f93..9b202fed3 100644
--- a/crates/rune/Cargo.toml
+++ b/crates/rune/Cargo.toml
@@ -19,7 +19,7 @@ default = ["emit"]
 emit = ["codespan-reporting"]
 bench = []
 workspace = ["toml", "toml-spanned-value", "semver", "relative-path", "serde-hashkey"]
-dynamic_fields = []
+dynamic_fields = ["rune-macros/dynamic_fields"]
 
 [dependencies]
 thiserror = "1.0.30"
diff --git a/tests/Cargo.toml b/tests/Cargo.toml
index d7253e202..11f79e846 100644
--- a/tests/Cargo.toml
+++ b/tests/Cargo.toml
@@ -13,11 +13,10 @@ path = "test.rs"
 [features]
 default = ["full"]
 full = ["rune-modules/full"]
-dynamic_fields = ["rune/dynamic_fields"]
 
 [dependencies]
 thiserror = "1.0.30"
 futures-executor = "0.3.0"
 
-rune = { path = "../crates/rune" }
+rune = { path = "../crates/rune", features = ["dynamic_fields"] }
 rune-modules = { path = "../crates/rune-modules", features = ["capture-io"] }