On Thu, May 09, 2024 at 12:51:28PM -0400, Jason Merrill wrote:
> On 5/9/24 12:03, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> >
> > -- >8 --
> > -Wsizeof-array-div offers a way to suppress the warning by wrapping
> > the second operand of the division in parens:
> >
> > sizeof (samplesBuffer) / (sizeof(unsigned char))
> >
> > but this doesn't work in a template, because we fail to propagate
> > the suppression bits. Do it, then.
> >
> > The finish_parenthesized_expr hunk is not needed because suppress_warning
> > isn't very fine-grained. But I think it makes sense to be explicit and
> > not rely on OPT_Wparentheses also suppressing OPT_Wsizeof_array_div.
> >
> > PR c++/114983
> >
> > gcc/cp/ChangeLog:
> >
> > * pt.cc (tsubst_expr) <case SIZEOF_EXPR>: Use copy_warning.
> > * semantics.cc (finish_parenthesized_expr): Also suppress
> > -Wsizeof-array-div.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/warn/Wsizeof-array-div3.C: New test.
> > ---
> > gcc/cp/pt.cc | 1 +
> > gcc/cp/semantics.cc | 2 ++
> > .../g++.dg/warn/Wsizeof-array-div3.C | 27 +++++++++++++++++++
> > 3 files changed, 30 insertions(+)
> > create mode 100644 gcc/testsuite/g++.dg/warn/Wsizeof-array-div3.C
> >
> > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> > index 8787eabb9fd..46cf8a737fb 100644
> > --- a/gcc/cp/pt.cc
> > +++ b/gcc/cp/pt.cc
> > @@ -20569,6 +20569,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
> > complain, tree in_decl)
> > TREE_SIDE_EFFECTS (r) = 0;
> > TREE_READONLY (r) = 1;
> > }
> > + copy_warning (r, t);
> > SET_EXPR_LOCATION (r, EXPR_LOCATION (t));
>
> copy_warning is defined in terms of locations (as well as TREE_NO_WARNING),
> so copying it before setting the location looks wrong.
Sigh. Since 'r' had no location, this just set TREE_NO_WARNING, also fixing
this test. But it's not what I meant to do.
Fixed below, thanks.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
-Wsizeof-array-div offers a way to suppress the warning by wrapping
the second operand of the division in parens:
sizeof (samplesBuffer) / (sizeof(unsigned char))
but this doesn't work in a template, because we fail to propagate
the suppression bits. Do it, then.
The finish_parenthesized_expr hunk is not needed because suppress_warning
isn't very fine-grained. But I think it makes sense to be explicit and
not rely on OPT_Wparentheses also suppressing OPT_Wsizeof_array_div.
PR c++/114983
gcc/cp/ChangeLog:
* pt.cc (tsubst_expr) <case SIZEOF_EXPR>: Use copy_warning.
* semantics.cc (finish_parenthesized_expr): Also suppress
-Wsizeof-array-div.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wsizeof-array-div3.C: New test.
---
gcc/cp/pt.cc | 1 +
gcc/cp/semantics.cc | 2 ++
.../g++.dg/warn/Wsizeof-array-div3.C | 27 +++++++++++++++++++
3 files changed, 30 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/warn/Wsizeof-array-div3.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 8787eabb9fd..a7d9fcf930e 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -20570,6 +20570,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
TREE_READONLY (r) = 1;
}
SET_EXPR_LOCATION (r, EXPR_LOCATION (t));
+ copy_warning (r, t);
}
RETURN (r);
}
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index b8c2bf8771f..71520dcd4fa 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -2306,6 +2306,8 @@ finish_parenthesized_expr (cp_expr expr)
/* This inhibits warnings in maybe_warn_unparenthesized_assignment
and c_common_truthvalue_conversion. */
suppress_warning (STRIP_REFERENCE_REF (*expr), OPT_Wparentheses);
+ /* And maybe_warn_sizeof_array_div. */
+ suppress_warning (STRIP_REFERENCE_REF (*expr), OPT_Wsizeof_array_div);
}
if (TREE_CODE (expr) == OFFSET_REF
diff --git a/gcc/testsuite/g++.dg/warn/Wsizeof-array-div3.C
b/gcc/testsuite/g++.dg/warn/Wsizeof-array-div3.C
new file mode 100644
index 00000000000..bfd690325e5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wsizeof-array-div3.C
@@ -0,0 +1,27 @@
+// PR c++/114983
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wsizeof-array-div" }
+
+using size_t = decltype (sizeof (0));
+unsigned int samplesBuffer[40];
+
+template <typename T>
+constexpr inline size_t fn1()
+{
+ return ((sizeof(samplesBuffer)) / (sizeof(T))); // { dg-bogus "expression
does not compute" }
+}
+
+template <typename T>
+constexpr inline size_t fn2()
+{
+ return ((sizeof(samplesBuffer)) / sizeof(T)); // { dg-warning "expression
does not compute" }
+}
+
+size_t
+g ()
+{
+ auto sz = sizeof (samplesBuffer) / (sizeof(unsigned char));
+ sz += fn1<unsigned char>();
+ sz += fn2<unsigned char>(); // { dg-message "required from here" }
+ return sz;
+}
base-commit: e02b5683e77c2b4317b23be72e43b6e6cc6c8e5b
--
2.45.0
