Use std::is_signed and std::enable_if

[kevinbackhouse]

Now that we're using C++11, we can use std::is_signed and std::enable_if.

[neheb]

is_signed_t

[neheb]

--- a/unitTests/test_safe_op.cpp
+++ b/unitTests/test_safe_op.cpp
@@ -26,19 +26,19 @@ struct AdditionTestValues;
  * Overload for unsigned types.
  */
 template <typename T>
-struct AdditionTestValues<T, typename std::enable_if<!std::is_signed<T>::VALUE>::type> {
+struct AdditionTestValues<T, std::enable_if_t<!std::is_signed_v<T>>> {
   static const size_t case_count = 5;
   static const T summand[case_count];
   static const bool overflow[case_count][case_count];
 };

 template <typename T>
-const T AdditionTestValues<T, typename std::enable_if<!std::is_signed<T>::VALUE>::type>::summand[] = {
+const T AdditionTestValues<T, std::enable_if_t<!std::is_signed_v<T>>>::summand[] = {
     0, 1, 2, static_cast<T>(std::numeric_limits<T>::max() - 1), std::numeric_limits<T>::max()};

 template <typename T>
 const bool AdditionTestValues<
-    T, typename std::enable_if<!std::is_signed<T>::VALUE>::type>::overflow[case_count][case_count] = {
+    T, std::enable_if_t<!std::is_signed_v<T>>>::overflow[case_count][case_count] = {
     // 0
     {false, false, false, false, false},
     // 1
@@ -54,14 +54,14 @@ const bool AdditionTestValues<
  * Overload for signed integers
  */
 template <typename T>
-struct AdditionTestValues<T, typename std::enable_if<std::is_signed<T>::VALUE>::type> {
+struct AdditionTestValues<T, std::enable_if_t<std::is_signed_v<T>>> {
   static const size_t case_count = 8;
   static const T summand[case_count];
   static const bool overflow[case_count][case_count];
 };

 template <typename T>
-const T AdditionTestValues<T, typename std::enable_if<std::is_signed<T>::VALUE>::type>::summand[] = {
+const T AdditionTestValues<T, std::enable_if_t<std::is_signed_v<T>>>::summand[] = {
     std::numeric_limits<T>::min(),
     static_cast<T>(std::numeric_limits<T>::min() + 1),
     -1,
@@ -73,7 +73,7 @@ const T AdditionTestValues<T, typename std::enable_if<std::is_signed<T>::VALUE>:

 template <typename T>
 const bool
-    AdditionTestValues<T, typename std::enable_if<std::is_signed<T>::VALUE>::type>::overflow[case_count][case_count] = {
+    AdditionTestValues<T, std::enable_if_t<std::is_signed_v<T>>>::overflow[case_count][case_count] = {
         // min
         {true, true, true, false, false, false, false, false},
         // min + 1

[kevinbackhouse]

@neheb: thanks, I added your suggestion in commit 2.

[codecov]

Codecov Report

Merging #2395 (d6df99e) into main (761acaf) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2395   +/-   ##
=======================================
  Coverage   64.28%   64.28%           
=======================================
  Files         119      119           
  Lines       21136    21136           
  Branches    10428    10428           
=======================================
  Hits        13587    13587           
  Misses       5400     5400           
  Partials     2149     2149           

Impacted Files	Coverage Δ
src/safe_op.hpp	96.87% <100.00%> (ø)

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[neheb]

I’ll note this works because exiv2 is c++17. This shouldn’t be done for public facing headers where C++11 is requested.

[kevinbackhouse]

This PR now uses these features:

• std::is_signed (C++11)
• std::enable_if (C++11)
• std::is_signed_v (C++17)
• std::enable_if_t (C++14)

The C++14, C++17 features are only used in unitTests/test_safe_op.cpp so they won't affect our public facing headers.

[neheb]

it looks like safe_op.hpp is a private header as well. It could use the same treatment.

[neheb]

I also noticed test_slice.cpp has several comments indicating a bunch of code can go away. Can you take a look?