I have developed a Fortran 2023 grammar using ANTLR4. You can find the grammar in my GitHub repository: Fortran2023Grammar. I am facing an issue while lexing the code where certain terms, such as real and size, are tokenized as reserved words. However, these terms are also used as intrinsic function names in Fortran.

I am developing a Fortran 2018 grammar in ANTLR4 using the ISO standard. I am encountering an issue during the lexing phase with some of the lexer rules. Specifically, certain keywords are being misclassified. Below is the minimal grammar demonstrating the problem: