Handle outer unsafe for whitelisted attrs

aarch32-rt-macros/CHANGELOG.md

@@ -10,6 +10,9 @@ As of *aarch32-rt-macros v0.1.0*, this project is released in lock-step with
 
 ## [Unreleased]
 
+- Handle outer `unsafe` for whitelisted proc macro attributes. For example, this allows
+  `#[unsafe(link_section="...")]` which previously did not work.
+
 ## [aarch32-rt-macros v0.2.0]
 
 - Changed `#[entry]`, `#[exception]` and `#[irq]` to hide the handler function

aarch32-rt-macros/src/lib.rs

@@ -455,6 +455,21 @@ fn check_attr_whitelist(attrs: &[Attribute], caller: VectorKind) -> Result<(), T
     ];
 
     'o: for attr in attrs {
+        // Also check whatever is wrapped inside `unsafe(...)`
+        if attr.path().is_ident("unsafe") {
+            let mut whitelisted = false;
+            let _ = attr.parse_nested_meta(|meta| {
+                for val in whitelist {
+                    if meta.path.is_ident(val) {
+                        whitelisted = true;
+                    }
+                }
+                Ok(())
+            });
+            if whitelisted {
+                continue 'o;
+            }
+        }
         for val in whitelist {
             if eq(attr, val) {
                 continue 'o;

examples/mps3-an536/src/bin/prefetch-exception-a32.rs

@@ -49,7 +49,9 @@ core::arch::global_asm!(
 "#
 );
 
+// Custom link sections are allowed as well.
 #[exception(Undefined)]
+#[unsafe(link_section = ".text._rust_undefined_handler")]
 fn undefined_handler(_addr: usize) -> ! {
     panic!("unexpected undefined exception");
 }