From: Qing Zhao <qing.zhao@oracle.com>
Date: Wed, 28 May 2025 21:13:38 +0000 (+0000)
Subject: C: Flex array in the middle via type alias is not reported [PR120353]
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f37c5f1d88c9da17f16cdb33e7c9d43e4bb5f64d;p=thirdparty%2Fgcc.git

C: Flex array in the middle via type alias is not reported [PR120353]

The root cause of the bug is: the TYPE_INCLUDES_FLEXARRAY marking of the
structure type is not copied to its aliased type.
The fix is to copy this marking to all the variant types of the current
structure type.

	PR c/120353

gcc/c/ChangeLog:

	* c-decl.cc (finish_struct): Copy TYPE_INCLUDES_FLEXARRAY marking
	to all the variant types of the current structure type.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr120353.c: New test.
---

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index e10f9c1ea7b..38de96e1287 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -9893,6 +9893,7 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes,
       C_TYPE_VARIABLE_SIZE (x) = C_TYPE_VARIABLE_SIZE (t);
       C_TYPE_VARIABLY_MODIFIED (x) = C_TYPE_VARIABLY_MODIFIED (t);
       C_TYPE_INCOMPLETE_VARS (x) = NULL_TREE;
+      TYPE_INCLUDES_FLEXARRAY (x) = TYPE_INCLUDES_FLEXARRAY (t);
     }
 
   /* Update type location to the one of the definition, instead of e.g.
diff --git a/gcc/testsuite/gcc.dg/pr120353.c b/gcc/testsuite/gcc.dg/pr120353.c
new file mode 100644
index 00000000000..6f8e4acf7f2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr120353.c
@@ -0,0 +1,11 @@
+/* PR120353: Test for -Wflex-array-member-not-at-end on structure with 
+   typedef.  */ 
+/* { dg-do compile } */
+/* { dg-options "-Wflex-array-member-not-at-end" } */
+
+typedef struct flex flex_t;
+struct flex { int n; int data[]; };
+struct out_flex_mid {flex_t flex_data;  int m; }; /* { dg-warning "structure containing a flexible array member is not at the end of another structure" } */
+
+typedef struct flex flex_t1;
+struct out_flex_mid1 {flex_t1 flex_data1; int n; }; /* { dg-warning "structure containing a flexible array member is not at the end of another structure" } */