iar - How to specify a compiler in CMake?

Question

I would like to use the IAR compiler. I noticed CMake has already have a bunch of files about this compiler:

https://github.com/jevinskie/cmake/blob/master/Modules/Compiler/IAR.cmake

From what I read the common solution is to specify manually ALL the toolchain in my CMakeLists.txt:

set(CMAKE_C_COMPILER iccarm)
set(CMAKE_CPP_COMPILER iccarm)

How CMake can link these definitions with `Modules/Compiler/IAR.cmake"?

I thought I would just have to do

include("Modules/Compiler/IAR.cmake")

What is the correct way to specify my IAR compiler?

When I do

cmake .

It still tries to use gcc instead of my IAR compiler. Why?

question from:https://stackoverflow.com/questions/45933732/how-to-specify-a-compiler-in-cmake

Answer 1

To select a specific compiler, you have several solutions, as exaplained in CMake wiki:

Method 1: use environment variables

For C and C++, set the CC and CXX environment variables. This method is not guaranteed to work for all generators. (Specifically, if you are trying to set Xcode's GCC_VERSION, this method confuses Xcode.) For example:

CC=gcc-4.2 CXX=/usr/bin/g++-4.2 cmake -G "Your Generator" path/to/your/source

Method 2: use cmake -D

Set the appropriate CMAKE_FOO_COMPILER variable(s) to a valid compiler name or full path on the command-line using cmake -D. For example:

cmake -G "Your Generator" -D CMAKE_C_COMPILER=gcc-4.2 -D CMAKE_CXX_COMPILER=g++-4.2 path/to/your/source

Method 3 (avoid): use set()

Set the appropriate CMAKE_FOO_COMPILER variable(s) to a valid compiler name or full path in a list file using set(). This must be done before any language is set (ie: before any project() or enable_language() command). For example:

set(CMAKE_C_COMPILER "gcc-4.2")
set(CMAKE_CXX_COMPILER "/usr/bin/g++-4.2")

project("YourProjectName")

The wiki doesn't provide reason why 3rd method should be avoided...