From 6434176909002b3183a7c82d2909d8c740407bf4 Mon Sep 17 00:00:00 2001
From: acqn <acqn163@outlook.com>
Date: Wed, 29 Nov 2023 12:27:01 +0800
Subject: [PATCH] Fixed constness of bit-fields.

---
 src/cc65/datatype.c         |  4 ++--
 src/cc65/datatype.h         |  4 ++--
 src/cc65/symtab.c           |  1 +
 test/err/bug2018-bitfield.c | 14 ++++++++++++++
 4 files changed, 19 insertions(+), 4 deletions(-)
 create mode 100644 test/err/bug2018-bitfield.c

diff --git a/src/cc65/datatype.c b/src/cc65/datatype.c
index 81727e491..9e0652526 100644
--- a/src/cc65/datatype.c
+++ b/src/cc65/datatype.c
@@ -497,8 +497,8 @@ Type* NewPointerTo (const Type* T)
 
 
 Type* NewBitFieldOf (const Type* T, unsigned BitOffs, unsigned BitWidth)
-/* Return a type string that is "T : BitWidth" aligned on BitOffs. The type
-** string is allocated on the heap and may be freed after use.
+/* Return a type string that is "unqualified T : BitWidth" aligned on BitOffs.
+** The type string is allocated on the heap and may be freed after use.
 */
 {
     Type* P;
diff --git a/src/cc65/datatype.h b/src/cc65/datatype.h
index 0890c4d12..4f4b6f25e 100644
--- a/src/cc65/datatype.h
+++ b/src/cc65/datatype.h
@@ -435,8 +435,8 @@ Type* NewPointerTo (const Type* T);
 */
 
 Type* NewBitFieldOf (const Type* T, unsigned BitOffs, unsigned BitWidth);
-/* Return a type string that is "T : BitWidth" aligned on BitOffs. The type
-** string is allocated on the heap and may be freed after use.
+/* Return a type string that is "unqualified T : BitWidth" aligned on BitOffs.
+** The type string is allocated on the heap and may be freed after use.
 */
 
 const Type* AddressOf (const Type* T);
diff --git a/src/cc65/symtab.c b/src/cc65/symtab.c
index d30e591c9..a4ca9e23d 100644
--- a/src/cc65/symtab.c
+++ b/src/cc65/symtab.c
@@ -1023,6 +1023,7 @@ SymEntry* AddBitField (const char* Name, const Type* T, unsigned Offs,
         } else {
             Entry->Type = NewBitFieldOf (T, BitOffs, BitWidth);
         }
+        Entry->Type[0].C |= GetQualifier (T) & T_MASK_QUAL;
 
         /* Add the entry to the symbol table */
         AddSymEntry (FieldTab, Entry);
diff --git a/test/err/bug2018-bitfield.c b/test/err/bug2018-bitfield.c
new file mode 100644
index 000000000..ea2928659
--- /dev/null
+++ b/test/err/bug2018-bitfield.c
@@ -0,0 +1,14 @@
+/* Bug #2018 - Compiler has problems with const struct fields */
+
+typedef union U {
+    int a : 16;
+    const int b : 16;
+} U;
+
+int main(void)
+{
+    U x = { 42 };
+    x.b = 0;
+
+    return 0;
+}