[gcc r10-7027] PR middle-end/81401 - false positive -Wformat-overflow in a loop

[Martin Sebor]

https://gcc.gnu.org/g:3ca63e1c76b7693b5d3f5ba2567421defc764249

commit r10-7027-g3ca63e1c76b7693b5d3f5ba2567421defc764249
Author: Martin Sebor <msebor@redhat.com>
Date:   Wed Mar 4 10:23:49 2020 -0700

    PR middle-end/81401 - false positive -Wformat-overflow in a loop
    
    gcc/testsuite/ChangeLog:
    	* gcc.dg/tree-ssa/builtin-sprintf-warn-24.c: New test.

Diff:
---
 gcc/testsuite/ChangeLog                            |  5 +++++
 .../gcc.dg/tree-ssa/builtin-sprintf-warn-24.c      | 22 ++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 83882d2..b28eb52 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-04  Martin Sebor  <msebor@redhat.com>
+
+	PR middle-end/81401
+	* gcc.dg/tree-ssa/builtin-sprintf-warn-24.c: New test.
+
 2020-03-04  Will Schmidt  <will_schmidt@vnet.ibm.com>
 
 	* gcc.target/powerpc/20050603-3.c: Remove XFAILS.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-24.c b/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-24.c
new file mode 100644
index 0000000..d910978
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-24.c
@@ -0,0 +1,22 @@
+/* PR middle-end/81401 - false positive -Wformat-overflow in a loop
+   { dg-do compile }
+   { dg-options "-O2 -Wall -Wformat-overflow" } */
+
+char a[3];
+
+void f (void)
+{
+  int i, i0 = 0x00;
+
+  for (i = i0; i <= 0xff; ++i)
+    __builtin_sprintf (a, "%02x", i);   // { dg-bogus "\\\[-Wformat-overflow" }
+}
+
+char b[2];
+
+void g (void)
+{
+  int i;
+  for (i = 0; i < 10; ++i)
+    __builtin_sprintf (b, "%d", i);     // { dg-bogus "\\\[-Wformat-overflow" }
+}