From 1c86a4bbebf6bce1f14f2e3e17ab132fb3ccb8db Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Fri, 14 Oct 2022 23:11:08 +0200
Subject: [PATCH]   * if a pointer_to_array type conversion is applied to a
 variable, it is not written, resolves #39957

---
 compiler/ncnv.pas       | 3 ++-
 tests/webtbs/tw39957.pp | 9 +++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 tests/webtbs/tw39957.pp

diff --git a/compiler/ncnv.pas b/compiler/ncnv.pas
index 7f33891c27..a6d63538a9 100644
--- a/compiler/ncnv.pas
+++ b/compiler/ncnv.pas
@@ -3775,7 +3775,8 @@ implementation
 
     procedure Ttypeconvnode.mark_write;
       begin
-        left.mark_write;
+        if not(convtype=tc_pointer_2_array) then
+          left.mark_write;
       end;
 
     function ttypeconvnode.first_cord_to_pointer : tnode;
diff --git a/tests/webtbs/tw39957.pp b/tests/webtbs/tw39957.pp
new file mode 100644
index 0000000000..863180ddac
--- /dev/null
+++ b/tests/webtbs/tw39957.pp
@@ -0,0 +1,9 @@
+{ %opt=-O4 -Oodeadstore -Oonoregvar }
+var
+	src: array[0 .. 9] of int32;
+	srcp: pInt32;
+
+begin
+	srcp := pInt32(src);
+	srcp[0] := 1;
+end.