[libcxx] [test] Fix MSVC warnings C4127 and C6326 about constants.

MSVC has compiler warnings C4127 "conditional expression is constant" (enabled
by /W4) and C6326 "Potential comparison of a constant with another constant"
(enabled by /analyze). They're potentially useful, although they're slightly
annoying to library devs who know what they're doing. In the latest version of
the compiler, C4127 is suppressed when the compiler sees simple tests like
"if (name_of_thing)", so extracting comparison expressions into named
constants is a workaround. At the same time, using std::integral_constant
avoids C6326, which doesn't look at template arguments.

test/std/containers/sequences/vector.bool/emplace.pass.cpp
Replace 1 == 1 with true, which is the same as far as the library is concerned.

Fixes D28837.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@292432 91177308-0d34-0410-b5e6-96231b3b80d8

10 files changed, 30 insertions, 12 deletions

diff --git a/test/std/utilities/function.objects/unord.hash/enum.pass.cpp b/test/std/utilities/function.objects/unord.hash/enum.pass.cpp
index af367789a..09ea034b7 100644
--- a/test/std/utilities/function.objects/unord.hash/enum.pass.cpp
+++ b/test/std/utilities/function.objects/unord.hash/enum.pass.cpp
@@ -43,7 +43,8 @@ test()
     for (int i = 0; i <= 5; ++i)
     {
         T t(static_cast<T> (i));
-        if (sizeof(T) <= sizeof(std::size_t))
+        const bool small = std::integral_constant<bool, sizeof(T) <= sizeof(std::size_t)>::value; // avoid compiler warnings
+        if (small)
             assert(h1(t) == h2(static_cast<under_type>(i)));
     }
 }
diff --git a/test/std/utilities/function.objects/unord.hash/integral.pass.cpp b/test/std/utilities/function.objects/unord.hash/integral.pass.cpp
index 2f3f9bee4..08a2a8c71 100644
--- a/test/std/utilities/function.objects/unord.hash/integral.pass.cpp
+++ b/test/std/utilities/function.objects/unord.hash/integral.pass.cpp
@@ -36,7 +36,8 @@ test()
     for (int i = 0; i <= 5; ++i)
     {
         T t(static_cast<T>(i));
-        if (sizeof(T) <= sizeof(std::size_t))
+        const bool small = std::integral_constant<bool, sizeof(T) <= sizeof(std::size_t)>::value; // avoid compiler warnings
+        if (small)
         {
             const std::size_t result = h(t);
             LIBCPP_ASSERT(result == static_cast<size_t>(t));
diff --git a/test/std/utilities/template.bitset/bitset.members/all.pass.cpp b/test/std/utilities/template.bitset/bitset.members/all.pass.cpp
index 5387b7339..de1cddb5b 100644
--- a/test/std/utilities/template.bitset/bitset.members/all.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/all.pass.cpp
@@ -10,6 +10,7 @@
 // test bool all() const;
 
 #include <bitset>
+#include <type_traits>
 #include <cassert>
 
 template <std::size_t N>
@@ -20,7 +21,8 @@ void test_all()
     assert(v.all() == (N == 0));
     v.set();
     assert(v.all() == true);
-    if (N > 1)
+    const bool greater_than_1 = std::integral_constant<bool, (N > 1)>::value; // avoid compiler warnings
+    if (greater_than_1)
     {
         v[N/2] = false;
         assert(v.all() == false);
diff --git a/test/std/utilities/template.bitset/bitset.members/any.pass.cpp b/test/std/utilities/template.bitset/bitset.members/any.pass.cpp
index aa6384a49..7ee83dd07 100644
--- a/test/std/utilities/template.bitset/bitset.members/any.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/any.pass.cpp
@@ -10,6 +10,7 @@
 // test bool any() const;
 
 #include <bitset>
+#include <type_traits>
 #include <cassert>
 
 template <std::size_t N>
@@ -20,7 +21,8 @@ void test_any()
     assert(v.any() == false);
     v.set();
     assert(v.any() == (N != 0));
-    if (N > 1)
+    const bool greater_than_1 = std::integral_constant<bool, (N > 1)>::value; // avoid compiler warnings
+    if (greater_than_1)
     {
         v[N/2] = false;
         assert(v.any() == true);
diff --git a/test/std/utilities/template.bitset/bitset.members/index.pass.cpp b/test/std/utilities/template.bitset/bitset.members/index.pass.cpp
index 02e58a789..f352475fc 100644
--- a/test/std/utilities/template.bitset/bitset.members/index.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/index.pass.cpp
@@ -10,6 +10,7 @@
 // test bitset<N>::reference operator[](size_t pos);
 
 #include <bitset>
+#include <type_traits>
 #include <cstdlib>
 #include <cassert>
 
@@ -31,7 +32,8 @@ template <std::size_t N>
 void test_index_const()
 {
     std::bitset<N> v1 = make_bitset<N>();
-    if (N > 0)
+    const bool greater_than_0 = std::integral_constant<bool, (N > 0)>::value; // avoid compiler warnings
+    if (greater_than_0)
     {
         assert(v1[N/2] == v1.test(N/2));
         typename std::bitset<N>::reference r = v1[N/2];
diff --git a/test/std/utilities/template.bitset/bitset.members/index_const.pass.cpp b/test/std/utilities/template.bitset/bitset.members/index_const.pass.cpp
index 870a504c2..fbde54859 100644
--- a/test/std/utilities/template.bitset/bitset.members/index_const.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/index_const.pass.cpp
@@ -10,6 +10,7 @@
 // test constexpr bool operator[](size_t pos) const;
 
 #include <bitset>
+#include <type_traits>
 #include <cstdlib>
 #include <cassert>
 
@@ -31,7 +32,8 @@ template <std::size_t N>
 void test_index_const()
 {
     const std::bitset<N> v1 = make_bitset<N>();
-    if (N > 0)
+    const bool greater_than_0 = std::integral_constant<bool, (N > 0)>::value; // avoid compiler warnings
+    if (greater_than_0)
     {
         assert(v1[N/2] == v1.test(N/2));
     }
diff --git a/test/std/utilities/template.bitset/bitset.members/none.pass.cpp b/test/std/utilities/template.bitset/bitset.members/none.pass.cpp
index b65c636f3..1358eaa62 100644
--- a/test/std/utilities/template.bitset/bitset.members/none.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/none.pass.cpp
@@ -10,6 +10,7 @@
 // test bool none() const;
 
 #include <bitset>
+#include <type_traits>
 #include <cassert>
 
 template <std::size_t N>
@@ -20,7 +21,8 @@ void test_none()
     assert(v.none() == true);
     v.set();
     assert(v.none() == (N == 0));
-    if (N > 1)
+    const bool greater_than_1 = std::integral_constant<bool, (N > 1)>::value; // avoid compiler warnings
+    if (greater_than_1)
     {
         v[N/2] = false;
         assert(v.none() == false);
diff --git a/test/std/utilities/template.bitset/bitset.members/op_eq_eq.pass.cpp b/test/std/utilities/template.bitset/bitset.members/op_eq_eq.pass.cpp
index 24761c628..5b7e10d67 100644
--- a/test/std/utilities/template.bitset/bitset.members/op_eq_eq.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/op_eq_eq.pass.cpp
@@ -13,6 +13,7 @@
 // bool operator!=(const bitset<N>& rhs) const;
 
 #include <bitset>
+#include <type_traits>
 #include <cstdlib>
 #include <cassert>
 
@@ -36,7 +37,8 @@ void test_equality()
     const std::bitset<N> v1 = make_bitset<N>();
     std::bitset<N> v2 = v1;
     assert(v1 == v2);
-    if (N > 0)
+    const bool greater_than_0 = std::integral_constant<bool, (N > 0)>::value; // avoid compiler warnings
+    if (greater_than_0)
     {
         v2[N/2].flip();
         assert(v1 != v2);
diff --git a/test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp b/test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp
index 27d8480d1..a2c9df6b4 100644
--- a/test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp
@@ -11,6 +11,7 @@
 
 #include <bitset>
 #include <algorithm>
+#include <type_traits>
 #include <climits>
 #include <cassert>
 
@@ -18,8 +19,9 @@ template <std::size_t N>
 void test_to_ullong()
 {
     const std::size_t M = sizeof(unsigned long long) * CHAR_BIT < N ? sizeof(unsigned long long) * CHAR_BIT : N;
-    const std::size_t X = M == 0 ? sizeof(unsigned long long) * CHAR_BIT - 1 : sizeof(unsigned long long) * CHAR_BIT - M;
-    const unsigned long long max = M == 0 ? 0 : (unsigned long long)(-1) >> X;
+    const bool is_M_zero = std::integral_constant<bool, M == 0>::value; // avoid compiler warnings
+    const std::size_t X = is_M_zero ? sizeof(unsigned long long) * CHAR_BIT - 1 : sizeof(unsigned long long) * CHAR_BIT - M;
+    const unsigned long long max = is_M_zero ? 0 : (unsigned long long)(-1) >> X;
     unsigned long long tests[] = {0,
                            std::min<unsigned long long>(1, max),
                            std::min<unsigned long long>(2, max),
diff --git a/test/std/utilities/template.bitset/bitset.members/to_ulong.pass.cpp b/test/std/utilities/template.bitset/bitset.members/to_ulong.pass.cpp
index 3ad1abade..7cabd06e5 100644
--- a/test/std/utilities/template.bitset/bitset.members/to_ulong.pass.cpp
+++ b/test/std/utilities/template.bitset/bitset.members/to_ulong.pass.cpp
@@ -11,6 +11,7 @@
 
 #include <bitset>
 #include <algorithm>
+#include <type_traits>
 #include <limits>
 #include <climits>
 #include <cassert>
@@ -19,8 +20,9 @@ template <std::size_t N>
 void test_to_ulong()
 {
     const std::size_t M = sizeof(unsigned long) * CHAR_BIT < N ? sizeof(unsigned long) * CHAR_BIT : N;
-    const std::size_t X = M == 0 ? sizeof(unsigned long) * CHAR_BIT - 1 : sizeof(unsigned long) * CHAR_BIT - M;
-    const std::size_t max = M == 0 ? 0 : std::size_t(std::numeric_limits<unsigned long>::max()) >> X;
+    const bool is_M_zero = std::integral_constant<bool, M == 0>::value; // avoid compiler warnings
+    const std::size_t X = is_M_zero ? sizeof(unsigned long) * CHAR_BIT - 1 : sizeof(unsigned long) * CHAR_BIT - M;
+    const std::size_t max = is_M_zero ? 0 : std::size_t(std::numeric_limits<unsigned long>::max()) >> X;
     std::size_t tests[] = {0,
                            std::min<std::size_t>(1, max),
                            std::min<std::size_t>(2, max),