sync

c/undefined-behaviour.md

@@ -70,3 +70,9 @@ The standard however may put constraints on what may happen.
 E.g.: argument order of evaluation `f1() * f2()`.
 
 Unlike undefined behaviour, we are sure that this will not produce nasal deamons: there are only two valid outcomes: `f1()` runs before or after `f2()`.
+
+## Trap representation
+
+TODO. Occurs with undefined behaviour? Or implementation defined signal?
+
+<http://stackoverflow.com/questions/6725809/trap-representation>

gcc/build.md

@@ -21,6 +21,8 @@ Summary:
     cd build
     # C and C++ only.
     ../src/configure --enable-languages=c,c++ --prefix="$(pwd)/../install"
+    # Add a suffix to the executable names:
+    # --program-suffix="-4.7"
     # All languages.
     # ../src/configure --enable-languages=all --prefix="$(pwd)/../install"
     # Wait hours.
@@ -31,6 +33,7 @@ Summary:
     # There are also many other installed files under /usr/local.
     sudo make install
     gcc -v
+    # sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9
 
 Or install locally for interactive testing:
 

opengl/configure

@@ -1,3 +1,4 @@
 #!/usr/bin/env bash
 sudo aptitude update
+# Ubuntu 14.04: glfw3 not present in repos, only glfw 2.
 sudo aptitude install -y freeglut3-dev libglfw3-dev libglew-dev libopencv-dev