Re: [PATCH] c++: Disable -Wint-in-bool-context in instantiations

[Jason Merrill via Gcc-patches]

On 5/12/21 12:21 PM, Marek Polacek wrote:

This warning is of questionable value when it's emitted when
instantiating a template, as in the following testcase.  It could be
silenced by writing hb(i) << 1 instead of 2 * hb(i) but that's
unnecessary obfuscation.

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

OK.

gcc/cp/ChangeLog:

        * pt.c (tsubst_copy_and_build): Add warn_int_in_bool_context
        sentinel.

gcc/testsuite/ChangeLog:

        * g++.dg/warn/Wint-in-bool-context-2.C: New test.
---
  gcc/cp/pt.c                                      |  1 +
  .../g++.dg/warn/Wint-in-bool-context-2.C         | 16 ++++++++++++++++
  2 files changed, 17 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/warn/Wint-in-bool-context-2.C

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 85c05af42ed..d7d6a3f2c14 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -19801,6 +19801,7 @@ tsubst_copy_and_build (tree t,

warning_sentinel s(warn_useless_cast);

        warning_sentinel s2(warn_ignored_qualifiers);
+       warning_sentinel s3(warn_int_in_bool_context);
        switch (TREE_CODE (t))
          {
          case CAST_EXPR:
diff --git a/gcc/testsuite/g++.dg/warn/Wint-in-bool-context-2.C 
b/gcc/testsuite/g++.dg/warn/Wint-in-bool-context-2.C
new file mode 100644
index 00000000000..6cb482d4dc9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wint-in-bool-context-2.C
@@ -0,0 +1,16 @@
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wint-in-bool-context" }
+
+unsigned hb(unsigned i) { return ~i; }
+
+template<typename T>
+void f(int i)
+{
+  auto l = [i]() { return T(2 * hb(i)); }; // { dg-bogus "in boolean context" }
+  (void) l;
+}
+
+int main()
+{
+  f<bool>(0);
+}

base-commit: 097fde5e7514e909f2e8472be2e008d0cab2260d