Re: [PATCH] c++: suppress -Wdangling-reference for std::span [PR107532]

[Jason Merrill via Gcc-patches]

On 3/10/23 14:07, Marek Polacek wrote:

std::span is a view and therefore should be treated as a reference
wrapper class for the purposes of -Wdangling-reference.  I'm not sure
there's a pattern that we could check for.

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?


OK.


PR c++/107532

gcc/cp/ChangeLog:

* call.cc (reference_like_class_p): Check for std::span.

gcc/testsuite/ChangeLog:

* g++.dg/warn/Wdangling-reference10.C: New test.
---
  gcc/cp/call.cc|  1 +
  gcc/testsuite/g++.dg/warn/Wdangling-reference10.C | 12 
  2 files changed, 13 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/warn/Wdangling-reference10.C

diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 3dfa12a0733..c01e7b82457 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -13800,6 +13800,7 @@ reference_like_class_p (tree ctype)
tree name = DECL_NAME (tdecl);
return (name
  && (id_equal (name, "reference_wrapper")
+ || id_equal (name, "span")
  || id_equal (name, "ref_view")));
  }
for (tree fields = TYPE_FIELDS (ctype);
diff --git a/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C 
b/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
new file mode 100644
index 000..733fb8cce63
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
@@ -0,0 +1,12 @@
+// PR c++/107532
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wdangling-reference" }
+
+#include 
+#include 
+
+void f(const std::vector& v)
+{
+  const int& r = std::span(v)[0]; // { dg-bogus "dangling 
reference" }
+  (void) r;
+}

base-commit: 20d790aa3ea5b0d240032cab997b8e0938cac62c

[PATCH] c++: suppress -Wdangling-reference for std::span [PR107532]

[Marek Polacek via Gcc-patches]

std::span is a view and therefore should be treated as a reference
wrapper class for the purposes of -Wdangling-reference.  I'm not sure
there's a pattern that we could check for.

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

PR c++/107532

gcc/cp/ChangeLog:

* call.cc (reference_like_class_p): Check for std::span.

gcc/testsuite/ChangeLog:

* g++.dg/warn/Wdangling-reference10.C: New test.
---
 gcc/cp/call.cc|  1 +
 gcc/testsuite/g++.dg/warn/Wdangling-reference10.C | 12 
 2 files changed, 13 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/warn/Wdangling-reference10.C

diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 3dfa12a0733..c01e7b82457 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -13800,6 +13800,7 @@ reference_like_class_p (tree ctype)
   tree name = DECL_NAME (tdecl);
   return (name
  && (id_equal (name, "reference_wrapper")
+ || id_equal (name, "span")
  || id_equal (name, "ref_view")));
 }
   for (tree fields = TYPE_FIELDS (ctype);
diff --git a/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C 
b/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
new file mode 100644
index 000..733fb8cce63
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wdangling-reference10.C
@@ -0,0 +1,12 @@
+// PR c++/107532
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wdangling-reference" }
+
+#include 
+#include 
+
+void f(const std::vector& v)
+{
+  const int& r = std::span(v)[0]; // { dg-bogus "dangling 
reference" }
+  (void) r;
+}

base-commit: 20d790aa3ea5b0d240032cab997b8e0938cac62c
-- 
2.39.2