From ba91a60669ae5788d2dfd795c09a8657f4963265 Mon Sep 17 00:00:00 2001
From: Sri Ganesh Thota <sriganeshthota12345@gmail.com>
Date: Wed, 11 Dec 2024 22:44:52 +0530
Subject: [PATCH] gccrs: feat: Made changes to ensure no wrong assignments are
 done.

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc (HIRCompileBase::lvalue_p): Created a function that
	checks the lvalue.
	* backend/rust-compile-base.h: Created the Signature for above function
	* backend/rust-compile-expr.cc (lvalue_p): Moved the function from here to
	rust-compile-base.
	(CompileExpr::visit): Made changes to ensure proper readability and checking for
	wrong assignments.

Signed-off-by: Sri Ganesh Thota <sriganeshthota12345@gmail.com>
---
 gcc/rust/backend/rust-compile-base.cc    | 46 ++++++++++++++++++++++++
 gcc/rust/backend/rust-compile-base.h     |  1 +
 gcc/rust/backend/rust-compile-expr.cc    | 13 ++++++-
 gcc/testsuite/rust/compile/issue-3287.rs | 12 +++++++
 4 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/rust/compile/issue-3287.rs

diff --git a/gcc/rust/backend/rust-compile-base.cc b/gcc/rust/backend/rust-compile-base.cc
index a4d0d062accc..b17c354b41e4 100644
--- a/gcc/rust/backend/rust-compile-base.cc
+++ b/gcc/rust/backend/rust-compile-base.cc
@@ -1015,5 +1015,51 @@ HIRCompileBase::unit_expression (location_t locus)
   return Backend::constructor_expression (unit_type, false, {}, -1, locus);
 }
 
+bool
+HIRCompileBase::lvalue_p (const_tree ref)
+{
+  const enum tree_code code = TREE_CODE (ref);
+
+  switch (code)
+    {
+    case REALPART_EXPR:
+    case IMAGPART_EXPR:
+    case COMPONENT_REF:
+      return lvalue_p (TREE_OPERAND (ref, 0));
+
+    case COMPOUND_LITERAL_EXPR:
+    case STRING_CST:
+    case CONST_DECL:
+    case INTEGER_CST:
+      return true;
+
+    case MEM_REF:
+    case TARGET_MEM_REF:
+      /* MEM_REFs can appear from -fgimple parsing or folding, so allow them
+	 here as well.  */
+    case INDIRECT_REF:
+    case ARRAY_REF:
+    case VAR_DECL:
+    case PARM_DECL:
+    case RESULT_DECL:
+    case ERROR_MARK:
+      return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
+	      && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
+
+    case BIND_EXPR:
+      return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
+    case PLUS_EXPR:
+    case MINUS_EXPR:
+    case MULT_EXPR:
+    case POINTER_PLUS_EXPR:
+    case POINTER_DIFF_EXPR:
+    case MULT_HIGHPART_EXPR:
+    case TRUNC_DIV_EXPR:
+      return false;
+    default:
+      return false;
+    }
+}
+
 } // namespace Compile
 } // namespace Rust
diff --git a/gcc/rust/backend/rust-compile-base.h b/gcc/rust/backend/rust-compile-base.h
index 3c50535552f5..5d9b015d94eb 100644
--- a/gcc/rust/backend/rust-compile-base.h
+++ b/gcc/rust/backend/rust-compile-base.h
@@ -30,6 +30,7 @@ class HIRCompileBase
   virtual ~HIRCompileBase () {}
 
   static tree address_expression (tree expr, location_t locus);
+  bool lvalue_p (const_tree ref);
 
 protected:
   HIRCompileBase (Context *ctx) : ctx (ctx) {}
diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 7323413bfce2..af8b73e88430 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -851,7 +851,7 @@ CompileExpr::visit (HIR::ContinueExpr &expr)
 
       if (!ctx->lookup_label_decl (ref, &label))
 	{
-	  rust_error_at (expr.get_label ().get_locus (),
+	  rust_error_at (expr.get_label ().get_locus (), ErrorCode::E0770,
 			 "failed to lookup compiled label");
 	  return;
 	}
@@ -964,6 +964,17 @@ CompileExpr::visit (HIR::AssignmentExpr &expr)
   auto lvalue = CompileExpr::Compile (expr.get_lhs (), ctx);
   auto rvalue = CompileExpr::Compile (expr.get_rhs (), ctx);
 
+  bool validl_value = lvalue_p (lvalue);
+
+  if (!validl_value
+      || expr.get_lhs ().get_expression_type ()
+	   == HIR::Expr::ExprType::Operator)
+    {
+      rust_error_at (expr.get_lhs ().get_locus (),
+		     "invalid left-hand side of assignment");
+      return;
+    }
+
   // assignments are coercion sites so lets convert the rvalue if necessary
   TyTy::BaseType *expected = nullptr;
   TyTy::BaseType *actual = nullptr;
diff --git a/gcc/testsuite/rust/compile/issue-3287.rs b/gcc/testsuite/rust/compile/issue-3287.rs
new file mode 100644
index 000000000000..c1ea9f63af64
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-3287.rs
@@ -0,0 +1,12 @@
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+pub fn main() {
+    unsafe {
+        let mut x = 42;
+        x + 1= 2; // { dg-error "invalid left-hand side of assignment" }
+        let format = "Result: %d\n\0" as *const str as *const i8;
+        printf(format, x);
+    }
+}
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