230630.071301.CST correct fortran makefile

fortran/tests/makefiles/Makefile.common

@@ -411,10 +411,12 @@ ftest_i2_r16_d1_tst_c ftest_i4_r16_d1_tst_c ftest_i8_r16_d1_tst_c ftest_i2_r16_d
 # 1. In the debug mode, our code includes the BACKTRACE function if the compiler is gfortran. This
 # makes the code not standard-conforming. So -std=f$(FSTD) cannot be imposed without -fall-intrinsics.
 # 2. As of 2022, -Wextra implies -Wcompare-reals, -Wunused-parameter, and -Wdo-subscript.
-# 3. For `$$((10#$(FS)))`, see https://stackoverflow.com/questions/24777597/value-too-great-for-base-error-token-is-08
+# 3. Do not write [[ $(FS) -lt 18 ]], which will not work if FS is 08. This is because constants
+# with a leading 0 are interpreted as octal (base-8) numbers within double brackets.
+# see https://stackoverflow.com/questions/24777597/value-too-great-for-base-error-token-is-08
 #GFORT := gfortran -pg  # Compile for profiling with the gprof profiler. Does not work with macOS on GitHub Actions due to missing gcrt1.o
 GFORT := gfortran
-GFSTD := $(shell  [[ $$(($(GFORT) -dumpversion 2>/dev/null || echo 0) | sed 's|\..*||') -gt 8 ]] && ([[ $$((10#$(FS))) -lt 18 ]] && echo -std=f2018 || echo -std=f20$(FS)) || echo "")
+GFSTD := $(shell  [[ $$(($(GFORT) -dumpversion 2>/dev/null || echo 0) | sed 's|\..*||') -gt 8 ]] && ([ $(FS) -lt 18 ] && echo -std=f2018 || echo -std=f20$(FS)) || echo "")
 # 1. gfortran 7 raises a false positive warning regarding "maybe-uninitialized" of allocatable arrays.
 # See https://stackoverflow.com/questions/56261880/fortran-re-allocation-on-assignment-and-gfortran-warnings
 # 2. As of gfortran 11, gfortran raises a false positive warning regarding "maybe-uninitialized" of