Hotfix arithmetic bug

There is a bug in util_arithmetic_expr that compares a pointer to a string.
This bug results in the function left_associative not working as expected.
And therefore produces wrong expression results for complicated expressions with ^ operators.

The test TEST_exr_3 + 4*2/(1 - 5)^2^3 is a very good example.
When we use left-associative (default for C) for the power operator, the expression x^2^3 should be (x^2)^3=x^6.
When we use right-associative (default for Fortran) for the power operator, the expression x^2^3 should be x^(2^3)=x^8.
This branch fixes this bug.

Additionally, this branch also fixed the problem that the Ragel state machine no longer compiles the *.rl files.
This branch also updates FortUTF to the latest version.

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requested review from @b381001

assigned to @b382190

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• 10139092 - Update FortUTF version

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Thank you very much for the fix. Our unittest seem already to payoff and reveal potential bugs :-)

I would like to add @m300196 as a reviewer here, since he is the original author of this code.

Thanks for fixing this! Regarding the test: Shouldn't we treat ^ as left-associative? This is C behavior, I think (and the code is written in C), while the Fortran world would prefer the right associativity.

But we'd certainly need to state this convention as a comment.

I am not that familiar with which (left or right) we should use. But in the original code, ^ was set to be right-associative. https://gitlab.dkrz.de/icon-libraries/libfortran-support/-/blob/hotfix_arithmetic_bug/src/util_arithmetic_expr.c#L17
Maybe because this code is only used by calling from a Fortran module?

I think that no one has encountered this problem so far in a practical application. But when I implemented this, I had the left-associative behavior (like in my unit test example) in mind. I would rather vote for adding the operator to the internal array of left-associative symbols.

Okay. I will change that accordingly.

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• fbd42b97 - Add the power operator to the left-associative list

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• 8e51431e - Update the comment, adding the Ragel compiler version

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mentioned in commit 8137bc69

merged