Tutorial Step2 Exercise 2 - Adding an Option Solutions

Usage
1

Tutorial Exercise 2 - Adding an Option Solutions
https://cmake.org/cmake/help/latest/guide/tutorial/Adding%20a%20Library.html#id6

Should the solution for TODO 11 be

#ifndef USE_MYMATH
#  include <cmath>
#endif

instead of just

#include <cmath>

as #include <cmath> is unnecessary when USE_MYMATH=OFF?

Should text just above TODO 12 read

First, from within MathFunctions/CMakeLists.txt create a library called SqrtLibrary that has sources mysqrt.cxx.

instead of

First, from within USE_MYMATH create a library called SqrtLibrary that has sources mysqrt.cxx.

?

The stated objective of TODO 12 and TODO 13 is to not compile mysqrt.cxx when USE_MYMATH=OFF.
The solutions displayed for TODO 12 and TODO 13 are not wrapped in if(USE_MYMATH) i.e. bare

  add_library(SqrtLibrary STATIC
              mysqrt.cxx
              )

and bare

  target_link_libraries(MathFunctions PRIVATE SqrtLibrary)

(the eagle-eyed can see from the indentation that these fragments were copied from a CMakeLists.txt where there was probably an enclosing if). But if we use these the given fragments as solutions without an enclosing ‘if’ then SqrtLibrary is always built and linked, even when USE_MYMATH=OFF.

I would presume the correct solution is:

if(USE_MYMATH)
  add_library(SqrtLibrary STATIC
              mysqrt.cxx
              )
  target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
endif()

where I see the build does not make SqrtLibrary when USE_MYMATH=OFF.

2

Cc: @betsy.mcphail