doc: remove usages of C++11

Now it's just the standard library.

.github/ISSUE_TEMPLATE/good_first_issue.md

@@ -15,7 +15,7 @@ assignees: ''
 
 #### Useful skills:
 
-<!-- (For example, “C++11 std::thread”, “Qt5 GUI and async GUI design” or “basic understanding of Bitcoin mining and the Bitcoin Core RPC interface”.) -->
+<!-- (For example, “std::thread”, “Qt5 GUI and async GUI design” or “basic understanding of Bitcoin mining and the Bitcoin Core RPC interface”.) -->
 
 #### Want to work on this issue?
 

src/random.cpp

@@ -62,7 +62,7 @@ static inline int64_t GetPerformanceCounter() noexcept
     __asm__ volatile ("rdtsc" : "=a"(r1), "=d"(r2)); // Constrain r1 to rax and r2 to rdx.
     return (r2 << 32) | r1;
 #else
-    // Fall back to using C++11 clock (usually microsecond or nanosecond precision)
+    // Fall back to using standard library clock (usually microsecond or nanosecond precision)
     return std::chrono::high_resolution_clock::now().time_since_epoch().count();
 #endif
 }
@@ -438,7 +438,7 @@ public:
 
 RNGState& GetRNGState() noexcept
 {
-    // This C++11 idiom relies on the guarantee that static variable are initialized
+    // This idiom relies on the guarantee that static variable are initialized
     // on first call, even when multiple parallel calls are permitted.
     static std::vector<RNGState, secure_allocator<RNGState>> g_rng(1);
     return g_rng[0];

src/random.h

@@ -250,7 +250,7 @@ public:
                                    /* interval [0..0] */ Dur{0};
     };
 
-    // Compatibility with the C++11 UniformRandomBitGenerator concept
+    // Compatibility with the UniformRandomBitGenerator concept
     typedef uint64_t result_type;
     static constexpr uint64_t min() { return 0; }
     static constexpr uint64_t max() { return std::numeric_limits<uint64_t>::max(); }

src/randomenv.cpp

@@ -250,7 +250,7 @@ void RandAddDynamicEnv(CSHA512& hasher)
     gettimeofday(&tv, nullptr);
     hasher << tv;
 #endif
-    // Probably redundant, but also use all the clocks C++11 provides:
+    // Probably redundant, but also use all the standard library clocks:
     hasher << std::chrono::system_clock::now().time_since_epoch().count();
     hasher << std::chrono::steady_clock::now().time_since_epoch().count();
     hasher << std::chrono::high_resolution_clock::now().time_since_epoch().count();

src/reverse_iterator.h

@@ -4,7 +4,7 @@
 #define BITCOIN_REVERSE_ITERATOR_H
 
 /**
- * Template used for reverse iteration in C++11 range-based for loops.
+ * Template used for reverse iteration in range-based for loops.
  *
  *   std::vector<int> v = {1, 2, 3, 4, 5};
  *   for (auto x : reverse_iterate(v))

src/test/random_tests.cpp

@@ -101,7 +101,7 @@ BOOST_AUTO_TEST_CASE(fastrandom_randbits)
     }
 }
 
-/** Does-it-compile test for compatibility with standard C++11 RNG interface. */
+/** Does-it-compile test for compatibility with standard library RNG interface. */
 BOOST_AUTO_TEST_CASE(stdrandom_test)
 {
     FastRandomContext ctx;