https://gcc.gnu.org/g:b63c7d92012f92e0517190cf263d29bbef8a06bf
commit r15-1381-gb63c7d92012f92e0517190cf263d29bbef8a06bf
Author: Jakub Jelinek <ja...@redhat.com>
Date: Mon Jun 17 19:24:05 2024 +0200
c-family: Fix -Warray-compare warning ICE [PR115290]
The warning code uses %D to print the ARRAY_REF first operands.
That works in the most common case where those operands are decls, but
as can be seen on the following testcase, they can be other expressions
with array type.
Just changing %D to %E isn't enough, because then the diagnostics can
suggest something like
note: use '&(x) != 0 ? (int (*)[32])&a : (int (*)[32])&b[0] == &(y) != 0 ?
(int (*)[32])&a : (int (*)[32])&b[0]' to compare the addresses
which is a bad suggestion, the %E printing doesn't know that the
warning code will want to add & before it and [0] after it.
So, the following patch adds ()s around the operand as well, but does
that only for non-decls, for decls keeps it as &arr[0] like before.
2024-06-17 Jakub Jelinek <ja...@redhat.com>
PR c/115290
* c-warn.cc (do_warn_array_compare): Use %E rather than %D for
printing op0 and op1; if those operands aren't decls, also print
parens around them.
* c-c++-common/Warray-compare-3.c: New test.
Diff:
---
gcc/c-family/c-warn.cc | 13 +++++++++----
gcc/testsuite/c-c++-common/Warray-compare-3.c | 13 +++++++++++++
2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc
index 7ddf6ea2ad8e..5e4fb7f0f0a9 100644
--- a/gcc/c-family/c-warn.cc
+++ b/gcc/c-family/c-warn.cc
@@ -3832,11 +3832,16 @@ do_warn_array_compare (location_t location, tree_code
code, tree op0, tree op1)
/* C doesn't allow +arr. */
if (c_dialect_cxx ())
inform (location, "use unary %<+%> which decays operands to pointers "
- "or %<&%D[0] %s &%D[0]%> to compare the addresses",
- op0, op_symbol_code (code), op1);
+ "or %<&%s%E%s[0] %s &%s%E%s[0]%> to compare the addresses",
+ DECL_P (op0) ? "" : "(", op0, DECL_P (op0) ? "" : ")",
+ op_symbol_code (code),
+ DECL_P (op1) ? "" : "(", op1, DECL_P (op1) ? "" : ")");
else
- inform (location, "use %<&%D[0] %s &%D[0]%> to compare the addresses",
- op0, op_symbol_code (code), op1);
+ inform (location,
+ "use %<&%s%E%s[0] %s &%s%E%s[0]%> to compare the addresses",
+ DECL_P (op0) ? "" : "(", op0, DECL_P (op0) ? "" : ")",
+ op_symbol_code (code),
+ DECL_P (op1) ? "" : "(", op1, DECL_P (op1) ? "" : ")");
}
}
diff --git a/gcc/testsuite/c-c++-common/Warray-compare-3.c
b/gcc/testsuite/c-c++-common/Warray-compare-3.c
new file mode 100644
index 000000000000..4725aa2b38bf
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Warray-compare-3.c
@@ -0,0 +1,13 @@
+/* PR c/115290 */
+/* { dg-do compile } */
+/* { dg-options "-Warray-compare" } */
+
+int a[32][32], b[32][32];
+
+int
+foo (int x, int y)
+{
+ return (x ? a : b) == (y ? a : b); /* { dg-warning "comparison between two
arrays" } */
+/* { dg-message "use '&\\\(\[^\n\r]*\\\)\\\[0\\\] ==
&\\\(\[^\n\r]*\\\)\\\[0\\\]' to compare the addresses" "" { target c } .-1 } */
+/* { dg-message "use unary '\\\+' which decays operands to pointers or
'&\\\(\[^\n\r]*\\\)\\\[0\\\] == &\\\(\[^\n\r]*\\\)\\\[0\\\]' to compare the
addresses" "" { target c++ } .-2 } */
+}
