Here is a summary of all the options specific to GNU Fortran, grouped by type. Explanations are in the following sections.
-fall-intrinsics -ffree-form -fno-fixed-form -fdollar-ok -fimplicit-none -fmax-identifier-length -std=std -fd-lines-as-code -fd-lines-as-comments -ffixed-line-length-n -ffixed-line-length-none -ffree-line-length-n -ffree-line-length-none -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 -fcray-pointer -fopenmp -fno-range-check -fbackslash -fmodule-private
-cpp -dD -dI -dM -dN -dU -fworking-directory -imultilib dir -iprefix file -isysroot dir -iquote -isystem dir -nocpp -nostdinc -undef -Aquestion=answer -A-question[=answer] -C -CC -Dmacro[=defn] -Umacro -H -P
-fmax-errors=n -fsyntax-only -pedantic -pedantic-errors -Wall -Waliasing -Wampersand -Warray-bounds -Wcharacter-truncation -Wconversion -Wimplicit-interface -Wimplicit-procedure -Wline-truncation -Wintrinsics-std -Wsurprising -Wno-tabs -Wunderflow -Wunused-parameter -Wintrinsic-shadow -Wno-align-commons
-fdump-fortran-original -fdump-fortran-optimized -ffpe-trap=list -fdump-core -fbacktrace -fdump-parse-tree
-Idir -Jdir -fintrinsic-modules-path dir
-static-libgfortran
-fconvert=conversion -fno-range-check -frecord-marker=length -fmax-subrecord-length=length -fsign-zero
-fno-automatic -ff2c -fno-underscoring -fno-whole-file -fsecond-underscore -fbounds-check -fcheck-array-temporaries -fmax-array-constructor =n -fcheck=<all|array-temps|bounds|do|mem|pointer|recursion> -fcoarray=<none|single> -fmax-stack-var-size=n -fpack-derived -frepack-arrays -fshort-enums -fexternal-blas -fblas-matmul-limit=n -frecursive -finit-local-zero -finit-integer=n -finit-real=<zero|inf|-inf|nan|snan> -finit-logical=<true|false> -finit-character=n -fno-align-commons -fno-protect-parens -frealloc-lhs