[PATCH] libstdc++: add parentheses around assignments used as truth values

Krystian Kuźniarek krystian.kuzniarek@gmail.com
Mon Aug 24 11:26:41 GMT 2020


Hi,

A description of the problem/bug and how your patch addresses it:
I've got a small patch for -Wparentheses in system headers.

Testcases:
N/A, it's only a warning.

ChangeLog:
Sorry, contrib/mklog.py didn't quite work for me.
For some reason after instruction in line 129: "diff = PatchSet(data)" my
"diff" variable is always empty.

Bootstrapping and testing:
Tested that manually by recompling GCC, unfolding all headers with
`#include <stdc++.h>` and compiling what's been included by it.

The patch itself:
diff --git a/libstdc++-v3/include/c_global/cmath
b/libstdc++-v3/include/c_global/cmath
index b99aaf8df40..25080511722 100644
--- a/libstdc++-v3/include/c_global/cmath
+++ b/libstdc++-v3/include/c_global/cmath
@@ -1893,7 +1893,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     constexpr _Fp
     __lerp(_Fp __a, _Fp __b, _Fp __t) noexcept
     {
-      if (__a <= 0 && __b >= 0 || __a >= 0 && __b <= 0)
+      if ((__a <= 0 && __b >= 0) || (__a >= 0 && __b <= 0))
  return __t * __b + (1 - __t) * __a;

       if (__t == 1)
@@ -1902,7 +1902,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // Exact at __t=0, monotonic except near __t=1,
       // bounded, determinate, and consistent:
       const _Fp __x = __a + __t * (__b - __a);
-      return __t > 1 == __b > __a
+      return (__t > 1) == (__b > __a)
  ? (__b < __x ? __x : __b)
  : (__b > __x ? __x : __b);  // monotonic near __t=1
     }


Best regards,
Krystian


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