Detect ICC vs GCC at compile time

Question

How to detect at compile time if I'm using gcc or icc?

(I was quite puzzled to find out that icc defines __GNUC__ -- and even __GNUC_MINOR__ and __GNUC_PATCHLEVEL__ ! why?)

Answer 1

We use

#ifdef __INTEL_COMPILER

to split icc off, assuming gcc as a default.

Answer 2

我相信你可以根据这个检查__INTEL_COMPILER 。

Answer 3

ICC定义__GNUC__等的原因是因为像你这样的代码检查编译器特定的宏并期望看到它们......

Answer 4

You can make the processor output the defined macros in the preprocessor output and look for a macro that suits you. You can generated the preprocessor output like this:

icc  -dM -E -o foo.P foo.c

Then look at foo.P (since it is a text file). In my case, I found icc defined an __ICC macro with the version of the compiler. It didn't define any __INTEL_COMPILER though.

Answer 5

Traditionally, compilers have defined a symbol of their own as well as their version as preprocessor symbols so that the code could be adapted (generally to work around bugs or specificities).

CLang has introduced a mechanism I had not seen so far, under the form of the __has_feature query. It does not replace the "work around bugs" practices (which is why CLang still exposes specific symbols) but allows a more natural style for querying the compiler capacities. I don't know if other compilers plan on defining such a facility.