Firstly, I just want to say that I think this project is awesome.
Secondly, I'm not even totally sure that the problem I'm about to describe is local to this project, but I'd like to "pay it forward", as it were, and describe the problem and a workaround.
Here's the problem: when starting the REPL with MIT Scheme, as configured with (setq geiser-active-implementations '(mit)), I encountered the following fatal error:
...
; Generating SCode for file: "emacs.scm" => "emacs.bin"... done
; Compiling file: "emacs.bin" => "emacs.c"...
; clang -DHAVE_CONFIG_H -DMIT_SCHEME -Wold-style-definition -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Wnested-externs -Wredundant-decls -Wall -Wundef -Wpointer-arith -Winline -O3 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -fconstant-cfstrings -DSIGNAL_HANDLERS_CAN_USE_SCHEME_STACK -frounding-math -DENABLE_LIARC_FILE_INIT -I/usr/local/Cellar/mit-scheme/9.2_2/lib/mit-scheme-c/include -o /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.o -c /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.c
; clang: warning: optimization flag '-frounding-math' is not supported [-Wignored-optimization-argument]
; clang -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -fconstant-cfstrings -DSIGNAL_HANDLERS_CAN_USE_SCHEME_STACK -Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -framework CoreFoundation -bundle -bundle_loader /usr/local/Cellar/mit-scheme/9.2_2/bin/mit-scheme-c -o /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.so /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.o
; ... done
...
It isn't totally clear to me why Clang is targeting a specific version — MacOSX10.14.sdk — but needless to say, the world has moved on.
Unfortunately, that string doesn't appear anywhere in this project, or I would've altered it and submitted a pull request.
As is, I went to the containing directory and made a symlink from MacOSX10.14.sdk to MacOSX.sdk. Parenthetically, I noticed that that directory already contained a symlink from MacOSX10.15.sdk to MacOSX.sdk.
Firstly, I just want to say that I think this project is awesome.
Secondly, I'm not even totally sure that the problem I'm about to describe is local to this project, but I'd like to "pay it forward", as it were, and describe the problem and a workaround.
Here's the problem: when starting the REPL with MIT Scheme, as configured with `(setq geiser-active-implementations '(mit))`, I encountered the following fatal error:
```
...
; Generating SCode for file: "emacs.scm" => "emacs.bin"... done
; Compiling file: "emacs.bin" => "emacs.c"...
; clang -DHAVE_CONFIG_H -DMIT_SCHEME -Wold-style-definition -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Wnested-externs -Wredundant-decls -Wall -Wundef -Wpointer-arith -Winline -O3 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -fconstant-cfstrings -DSIGNAL_HANDLERS_CAN_USE_SCHEME_STACK -frounding-math -DENABLE_LIARC_FILE_INIT -I/usr/local/Cellar/mit-scheme/9.2_2/lib/mit-scheme-c/include -o /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.o -c /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.c
; clang: warning: optimization flag '-frounding-math' is not supported [-Wignored-optimization-argument]
; clang -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -fconstant-cfstrings -DSIGNAL_HANDLERS_CAN_USE_SCHEME_STACK -Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -framework CoreFoundation -bundle -bundle_loader /usr/local/Cellar/mit-scheme/9.2_2/bin/mit-scheme-c -o /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.so /Users/me/.emacs.d/elpa/geiser-20191126.933/scheme/mit/geiser/emacs.o
; ... done
...
```
It isn't totally clear to me why Clang is targeting a specific version — `MacOSX10.14.sdk` — but needless to say, the world has moved on.
Unfortunately, that string doesn't appear anywhere in this project, or I would've altered it and submitted a pull request.
As is, I went to the containing directory and made a symlink from `MacOSX10.14.sdk` to `MacOSX.sdk`. Parenthetically, I noticed that that directory already contained a symlink from `MacOSX10.15.sdk` to `MacOSX.sdk`.
[Thanks and you're welcome.](https://www.youtube.com/watch?v=79DijItQXMM)