Recently I started getting following error: ``` [nix-shell:~/ghc]$ "inplace/bin/ghc-stage1" -optc-Wall -optc-Wall -optc-Wextra -optc-Wstrict-prototypes -optc-Wmissing-prototypes -optc-Wmissing-declarations -optc-Winline -optc-Wpointer-arith -optc-Wmissing-noreturn -optc-Wnested-externs -optc-Wredundant-decls -optc-Wno-aggregate-return -optc-Iincludes -optc-Iincludes/dist -optc-Iincludes/dist-derivedconstants/header -optc-Iincludes/dist-ghcconstants/header -optc-Iincludes/dist-install/build -optc-Irts -optc-Irts/dist/build -optc-DCOMPILING_RTS -optc-DFS_NAMESPACE=rts -optc-fno-strict-aliasing -optc-fno-common -optc-DDTRACE -optc-Irts/dist/build/./autogen -optc-Wno-unknown-pragmas -optc-O2 -optc-fomit-frame-pointer -optc-g -optc-DRtsWay=\"rts_thr\" -static -optc-DTHREADED_RTS -O0 -H64m -Wall -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Iincludes/dist-install/build -Irts -Irts/dist/build -DCOMPILING_RTS -DFS_NAMESPACE=rts -this-unit-id rts -dcmm-lint -DDTRACE -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen -O2 -Wcpp-undef -Wnoncanonical-monad-instances -c rts/sm/Scav_thr.c -o rts/dist/build/sm/Scav_thr.thr_o -v Glasgow Haskell Compiler, Version 8.11.0.20191222, stage 1 booted by GHC version 8.6.5 *** initializing package database: Using binary package database: /Users/ggreif/ghc/inplace/lib/package.conf.d/package.cache package flags [] loading package database /Users/ggreif/ghc/inplace/lib/package.conf.d wired-in package ghc-prim mapped to ghc-prim-0.6.1 wired-in package integer-wired-in mapped to integer-gmp-1.0.2.0 wired-in package base mapped to base-4.14.0.0 wired-in package rts mapped to rts wired-in package template-haskell mapped to template-haskell-2.16.0.0 wired-in package ghc mapped to ghc-8.11.0.20191222 !!! initializing package database: finished in 8.51 milliseconds, allocated 8.770 megabytes Created temporary directory: /var/folders/39/lr50t0q96tx5qp0mzht34r240000gn/T/ghc55616_0 *** systool:cc: *** C Compiler: /nix/store/mq8dqgqf2qqkp77pzf3jwc05px8rkbny-clang-wrapper-9.0.0/bin/cc -x c rts/sm/Scav_thr.c -o /var/folders/39/lr50t0q96tx5qp0mzht34r240000gn/T/ghc55616_0/ghc_1.s -fno-common -U__PIC__ -D__PIC__ -Wimplicit -S -O2 -include /Users/ggreif/ghc/includes/ghcversion.h -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Iincludes/dist-install/build -Irts -Irts/dist/build -Irts/dist/build -Irts/dist/build/./autogen -I/Users/ggreif/ghc/libraries/base/include -I/Users/ggreif/ghc/libraries/base/dist-install/build/include -I/Users/ggreif/ghc/libraries/base/dist-install/build/dist-install/build/include -I/Users/ggreif/ghc/libraries/integer-gmp/include -I/Users/ggreif/ghc/libraries/integer-gmp/dist-install/build/include -I/Users/ggreif/ghc/libraries/integer-gmp/dist-install/build/dist-install/build/include -I/Users/ggreif/ghc/rts/dist/build -I/Users/ggreif/ghc/includes -I/Users/ggreif/ghc/includes/dist-derivedconstants/header -I/Users/ggreif/ghc/includes/dist-install/build -Xpreprocessor -DCOMPILING_RTS -Xpreprocessor '-DFS_NAMESPACE=rts' -Xpreprocessor -DDTRACE -Wall -Wall -Wextra -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Winline -Wpointer-arith -Wmissing-noreturn -Wnested-externs -Wredundant-decls -Wno-aggregate-return -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Iincludes/dist-install/build -Irts -Irts/dist/build -DCOMPILING_RTS '-DFS_NAMESPACE=rts' -fno-strict-aliasing -fno-common -DDTRACE -Irts/dist/build/./autogen -Wno-unknown-pragmas -O2 -fomit-frame-pointer -g '-DRtsWay="rts_thr"' -DTHREADED_RTS In file included from rts/sm/Scav_thr.c:3:0: error: In file included from rts/sm/Scav.c:51:0: error: In file included from rts/sm/GCUtils.h:18:0: error: rts/sm/GCTDecl.h:113:1: error: error: register '%r13' unsuitable for global register variables on this target | 113 | GCT_REG_DECL(gc_thread*, gct, REG_Base); | ^ GCT_REG_DECL(gc_thread*, gct, REG_Base); ^ rts/sm/GCTDecl.h:37:56: error: note: expanded from macro 'GCT_REG_DECL' | 37 | #define GCT_REG_DECL(type,name,reg) register type name REG(reg); | ^ #define GCT_REG_DECL(type,name,reg) register type name REG(reg); ^ includes/stg/MachRegs.h:160:24: error: note: expanded from macro 'REG' | 160 | #define REG(x) __asm__("%" #x) | ^ #define REG(x) __asm__("%" #x) ^ 1 error generated. *** Deleting temp files: Deleting: /var/folders/39/lr50t0q96tx5qp0mzht34r240000gn/T/ghc55616_0/ghc_1.s /var/folders/39/lr50t0q96tx5qp0mzht34r240000gn/T/ghc55616_0/ghc_2.rsp Warning: deleting non-existent /var/folders/39/lr50t0q96tx5qp0mzht34r240000gn/T/ghc55616_0/ghc_1.s *** Deleting temp dirs: Deleting: /var/folders/39/lr50t0q96tx5qp0mzht34r240000gn/T/ghc55616_0 `cc' failed in phase `C Compiler'. (Exit code: 1) ``` My $CC is clang-9 (but I also tried others). Has anybody seen something similar? Cheers nd thanks, Gabor