[gcc r17-3112] gccrs: Apply try-finally cleanup for function-scope drops

https://gcc.gnu.org/g:35e344e5ccd0889840e3a7f164403cb36e525ce0

commit r17-3112-g35e344e5ccd0889840e3a7f164403cb36e525ce0
Author: Lishin <[email protected]>
Date:   Thu Jul 16 19:36:10 2026 +0000

    gccrs: Apply try-finally cleanup for function-scope drops
    
    Remove the individual drop-emission calls, and centralize
    function-scope drop by building the cleanup and popping block.
    
    Apply the same cleanup path to constant-item and closure function
    bodies.
    
    gcc/rust/ChangeLog:
    
            * backend/rust-compile-base.cc (HIRCompileBase::compile_function_body):
            Stop emitting drops directly in functions.
            (HIRCompileBase::compile_function): Use try-finally drop cleanup.
            (HIRCompileBase::compile_constant_item): Use try-finally drop cleanup.
            * backend/rust-compile-drop.cc
            (CompileDrop::emit_current_scope_drop_calls): Remove.
            * backend/rust-compile-drop.h: Remove the unused function declaration.
            * backend/rust-compile-expr.cc
            (CompileExpr::generate_closure_function): Use try-finally drop cleanup.
    
    Signed-off-by: Lishin <[email protected]>

Diff:
---
 gcc/rust/backend/rust-compile-base.cc | 15 ++++++++-------
 gcc/rust/backend/rust-compile-drop.cc |  8 --------
 gcc/rust/backend/rust-compile-drop.h  |  1 -
 gcc/rust/backend/rust-compile-expr.cc |  5 ++++-
 4 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/gcc/rust/backend/rust-compile-base.cc b/gcc/rust/backend/rust-compile-base.cc
index 04696787e407..7f9c56ca7b44 100644
--- a/gcc/rust/backend/rust-compile-base.cc
+++ b/gcc/rust/backend/rust-compile-base.cc
@@ -728,8 +728,6 @@ HIRCompileBase::compile_function_body (tree fndecl,
 							   return_value, locus);
 	  ctx->add_statement (assignment);
 
-	  CompileDrop (ctx).emit_current_scope_drop_calls ();
-
 	  result_reference = Backend::var_expression (fnctx.ret_addr, locus);
 	  tree return_stmt
 	    = Backend::return_statement (fndecl, result_reference, locus);
@@ -740,8 +738,6 @@ HIRCompileBase::compile_function_body (tree fndecl,
 	  // just add the stmt expression
 	  ctx->add_statement (return_value);
 
-	  CompileDrop (ctx).emit_current_scope_drop_calls ();
-
 	  // now just return unit expression
 	  tree unit_expr = unit_expression (locus);
 	  tree return_stmt
@@ -755,7 +751,7 @@ HIRCompileBase::compile_function_body (tree fndecl,
       // errors should have occurred
       location_t locus = function_body.get_locus ();
       tree return_value = unit_expression (locus);
-      CompileDrop (ctx).emit_current_scope_drop_calls ();
+
       tree return_stmt
 	= Backend::return_statement (fndecl, return_value, locus);
       ctx->add_statement (return_stmt);
@@ -917,7 +913,10 @@ HIRCompileBase::compile_function (
 
   ctx->push_fn (fndecl, return_address, tyret);
   compile_function_body (fndecl, *function_body, tyret);
-  tree bind_tree = ctx->pop_block ();
+
+  tree cleanup = CompileDrop (ctx).build_current_scope_drop_cleanup ();
+  tree bind_tree
+    = ctx->pop_block_with_cleanup (cleanup, function_body->get_locus ());
 
   gcc_assert (TREE_CODE (bind_tree) == BIND_EXPR);
   DECL_SAVED_TREE (fndecl) = bind_tree;
@@ -1002,7 +1001,9 @@ HIRCompileBase::compile_constant_item (
       ctx->add_statement (return_expr);
     }
 
-  tree bind_tree = ctx->pop_block ();
+  tree cleanup = CompileDrop (ctx).build_current_scope_drop_cleanup ();
+  tree bind_tree
+    = ctx->pop_block_with_cleanup (cleanup, const_value_expr.get_locus ());
 
   gcc_assert (TREE_CODE (bind_tree) == BIND_EXPR);
   DECL_SAVED_TREE (fndecl) = bind_tree;
diff --git a/gcc/rust/backend/rust-compile-drop.cc b/gcc/rust/backend/rust-compile-drop.cc
index 0062f30e2611..ab63e9751146 100644
--- a/gcc/rust/backend/rust-compile-drop.cc
+++ b/gcc/rust/backend/rust-compile-drop.cc
@@ -120,13 +120,5 @@ CompileDrop::build_current_scope_drop_cleanup ()
   return Backend::statement_list (drop_stmts);
 }
 
-void
-CompileDrop::emit_current_scope_drop_calls ()
-{
-  tree cleanup = build_current_scope_drop_cleanup ();
-  if (cleanup != NULL_TREE)
-    ctx->add_statement (cleanup);
-}
-
 } // namespace Compile
 } // namespace Rust
diff --git a/gcc/rust/backend/rust-compile-drop.h b/gcc/rust/backend/rust-compile-drop.h
index dea3e19359ba..f270356e1ee9 100644
--- a/gcc/rust/backend/rust-compile-drop.h
+++ b/gcc/rust/backend/rust-compile-drop.h
@@ -32,7 +32,6 @@ public:
   bool type_has_drop_impl (TyTy::BaseType *ty);
 
   tree build_current_scope_drop_cleanup ();
-  void emit_current_scope_drop_calls ();
 
 private:
   tree compile_drop_call (Bvariable *var, TyTy::BaseType *ty, location_t locus);
diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 4bcd11da4166..52ddffd1df5e 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -24,6 +24,7 @@
 #include "rust-compile-pattern.h"
 #include "rust-compile-resolve-path.h"
 #include "rust-compile-block.h"
+#include "rust-compile-drop.h"
 #include "rust-compile-implitem.h"
 #include "rust-constexpr.h"
 #include "rust-compile-type.h"
@@ -2907,7 +2908,9 @@ CompileExpr::generate_closure_function (HIR::ClosureExpr &expr,
       ctx->add_statement (return_expr);
     }
 
-  tree bind_tree = ctx->pop_block ();
+  tree cleanup = CompileDrop (ctx).build_current_scope_drop_cleanup ();
+  tree bind_tree
+    = ctx->pop_block_with_cleanup (cleanup, function_body.get_locus ());
 
   gcc_assert (TREE_CODE (bind_tree) == BIND_EXPR);
   DECL_SAVED_TREE (fndecl) = bind_tree;