Fix signed integer overflow UB in complexity computations.

Previously the FittingCurve functions for n^2 and n^3 did the calculation using int types. This can overflow and cause UB. This patch changes the calculations to use std::pow to prevent this. Also re-enable VC 2013 appveyor bot since I *hope* this is what was causing the failures.

Fix signed integer overflow UB in complexity computations.
c04f703a · Eric Fiselier · 5121b854 · c04f703a · c04f703a
Commit c04f703a authored Aug 07, 2016 by Eric Fiselier
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appveyor.yml appveyor.yml +1 -1

complexity.cc src/complexity.cc +2 -2

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--- a/appveyor.yml
+++ b/appveyor.yml
@@ -12,7 +12,7 @@ platform:

 environment:
  matrix:
-#    - compiler: msvc-12-seh
+    - compiler: msvc-12-seh
    - compiler: msvc-14-seh
    - compiler: gcc-4.9.2-posix
 #    - compiler: gcc-4.8.4-posix

--- a/src/complexity.cc
+++ b/src/complexity.cc
@@ -31,9 +31,9 @@ BigOFunc* FittingCurve(BigO complexity) {
    case oN:
      return [](int n) -> double { return n; };
    case oNSquared:
-      return [](int n) -> double { return n * n; };
+      return [](int n) -> double { return std::pow(n, 2); };
    case oNCubed:
-      return [](int n) -> double { return n * n * n; };
+      return [](int n) -> double { return std::pow(n, 3); };
    case oLogN:
      return [](int n) { return std::log2(n); };
    case oNLogN: