[gcc r17-3087] gccrs: Add new checks for `#[repr(align)]` attribute

https://gcc.gnu.org/g:5f8db9c25f054be5107d4adf679669d1d3cd5c19

commit r17-3087-g5f8db9c25f054be5107d4adf679669d1d3cd5c19
Author: Yap Zhi Heng <[email protected]>
Date:   Mon Jul 6 20:12:50 2026 +0800

    gccrs: Add new checks for `#[repr(align)]` attribute
    
    gcc/rust/ChangeLog:
    
            * typecheck/rust-hir-type-check-base.cc (TypeCheckBase::parse_repr_options): New
            check for `#[repr(align)]` to enforce having a parameter that is a power of 2.
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/invalid_repr_hint.rs: Update existing and add new `align` test cases.
    
    Signed-Off-By: Yap Zhi Heng <[email protected]>

Diff:
---
 gcc/rust/typecheck/rust-hir-type-check-base.cc  | 13 +++++++++++++
 gcc/testsuite/rust/compile/invalid_repr_hint.rs |  5 ++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/typecheck/rust-hir-type-check-base.cc b/gcc/rust/typecheck/rust-hir-type-check-base.cc
index 7ff37c92434c..f966f002aa2b 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-base.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-base.cc
@@ -522,6 +522,15 @@ TypeCheckBase::parse_repr_options (const AST::AttrVec &attrs, location_t locus)
 
 	  if (oparen == std::string::npos)
 	    {
+	      if (inline_option.compare ("align") == 0)
+		{
+		  rust_error_at (attr.get_locus (), ErrorCode::E0589,
+				 "invalid %<repr(align)%> attribute: %<align%> "
+				 "needs an argument");
+		  delete meta_items;
+		  break;
+		}
+
 	      is_pack = inline_option.compare ("packed") == 0;
 	      is_c = inline_option.compare ("C") == 0;
 	      is_integer = (inline_option.compare ("isize") == 0
@@ -571,6 +580,10 @@ TypeCheckBase::parse_repr_options (const AST::AttrVec &attrs, location_t locus)
 	    }
 	  else if (is_align)
 	    {
+	      if (value == 0 || (value & (value - 1)) != 0)
+		rust_error_at (
+		  attr.get_locus (), ErrorCode::E0589,
+		  "invalid %<repr(align)%> attribute: not a power of two");
 	      repr.repr_kind = TyTy::ADTType::ReprKind::ALIGN;
 	      repr.align = value;
 	    }
diff --git a/gcc/testsuite/rust/compile/invalid_repr_hint.rs b/gcc/testsuite/rust/compile/invalid_repr_hint.rs
index 7ac48a921d4d..5e1af4d1c530 100644
--- a/gcc/testsuite/rust/compile/invalid_repr_hint.rs
+++ b/gcc/testsuite/rust/compile/invalid_repr_hint.rs
@@ -6,7 +6,10 @@ struct Foo {
     x: i32,
 }
 
-#[repr(align)] // { dg-error "unrecognized representation hint" }
+#[repr(align)] // { dg-error "invalid .repr.align.. attribute: .align. needs an argument" }
 struct Bar {
     x: i32,
 }
+
+#[repr(align(3))] // { dg-error "invalid .repr.align.. attribute: not a power of two" }
+struct Baz {}