[gcc r14-8316] C23: Fix ICE for composite type for structs with unsigned bitfields [PR113492]

[gcc r14-8316] C23: Fix ICE for composite type for structs with unsigned bitfields [PR113492]

[Martin Uecker]

https://gcc.gnu.org/g:1ead42f9836a13cbbe6a2be685f76750583ae320

commit r14-8316-g1ead42f9836a13cbbe6a2be685f76750583ae320
Author: Martin Uecker <uecker@tugraz.at>
Date:   Sat Jan 20 19:03:57 2024 +0100

    C23: Fix ICE for composite type for structs with unsigned bitfields [PR113492]
    
    This patch fixes a bug when forming a composite type from structs that
    contain an unsigned bitfield declared with int while using -funsigned-bitfields.
    In such structs the unsigned integer type was not compatible to the
    regular unsigned integer type used elsewhere in the C FE.
    
            PR c/113492
    gcc/c:
            * c-decl.cc (grokdeclarator): Use c_common_unsigned_type instead of
            unsigned_type_for to create the unsigned type for bitfields declared
            with int when using -funsigned-bitfields.
    
    gcc/testsuite:
            * gcc.dg/pr113492.c: New test.

Diff:
---
 gcc/c/c-decl.cc                 |  2 +-
 gcc/testsuite/gcc.dg/pr113492.c | 43 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 4029bbc59fe..8d18a3e11f4 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -6947,7 +6947,7 @@ grokdeclarator (const struct c_declarator *declarator,
      "signed".  */
   if (bitfield && !flag_signed_bitfields && !declspecs->explicit_signed_p
       && TREE_CODE (type) == INTEGER_TYPE)
-    type = unsigned_type_for (type);
+    type = c_common_unsigned_type (type);
 
   /* Figure out the type qualifiers for the declaration.  There are
      two ways a declaration can become qualified.  One is something
diff --git a/gcc/testsuite/gcc.dg/pr113492.c b/gcc/testsuite/gcc.dg/pr113492.c
new file mode 100644
index 00000000000..56296c51072
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr113492.c
@@ -0,0 +1,43 @@
+/* PR 113492
+ * { dg-do compile }
+ * { dg-options "-std=c23 -funsigned-bitfields" } */
+
+struct foo {
+	int i : 3;
+} i;
+
+void test()
+{
+	struct foo {
+		unsigned i : 3;
+	} u;
+
+	1 ? i : u;
+	1 ? u : i;
+}
+	
+struct bar {
+	unsigned i : 3;
+} u;
+
+void test2()
+{
+	struct bar {
+		int i : 3;
+	} i;
+
+	1 ? i : u;
+	1 ? u : i;
+}
+	
+void test3()
+{
+	typedef int myint;
+	struct bar {
+		myint i : 3;
+	} i;
+
+	1 ? i : u;
+	1 ? u : i;
+}
+