Build with traps on signed overflow

This is UB, we should not be doing it, and we can cheaply turn it into
crashes reliably. We would much rather have crashes than the program
doing something silly.

Benchmarks, but i wonder if they are nonsense because they get identical
times across compilers?!

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `result-clang/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 375.5 ± 24.0 | 353.8 | 408.8 | 1.00 |
| `result-gcc/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 407.9 ± 26.0 | 385.1 | 449.5 | 1.09 ± 0.10 |
| `result-clangsan/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 382.2 ± 26.6 | 354.9 | 419.0 | 1.02 ± 0.10 |
| `result-gccsan/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 408.6 ± 24.6 | 384.5 | 441.9 | 1.09 ± 0.10 |

| Command | Mean [s] | Min [s] | Max [s] | Relative |
|:---|---:|---:|---:|---:|
| `result-clang/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 17.199 ± 0.167 | 16.930 | 17.499 | 1.01 ± 0.01 |
| `result-gcc/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 17.409 ± 0.126 | 17.242 | 17.633 | 1.02 ± 0.01 |
| `result-clangsan/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 17.080 ± 0.137 | 16.879 | 17.350 | 1.00 |
| `result-gccsan/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 17.396 ± 0.160 | 17.131 | 17.660 | 1.02 ± 0.01 |

| Command | Mean [s] | Min [s] | Max [s] | Relative |
|:---|---:|---:|---:|---:|
| `result-clang/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 6.267 ± 0.069 | 6.197 | 6.415 | 1.02 ± 0.01 |
| `result-gcc/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 6.232 ± 0.045 | 6.180 | 6.311 | 1.01 ± 0.01 |
| `result-clangsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 6.162 ± 0.020 | 6.133 | 6.196 | 1.00 |
| `result-gccsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 6.229 ± 0.031 | 6.199 | 6.289 | 1.01 ± 0.01 |

| Command | Mean [s] | Min [s] | Max [s] | Relative |
|:---|---:|---:|---:|---:|
| `GC_INITIAL_HEAP_SIZE=10g result-clang/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 4.683 ± 0.044 | 4.630 | 4.761 | 1.00 |
| `GC_INITIAL_HEAP_SIZE=10g result-gcc/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 4.750 ± 0.041 | 4.680 | 4.812 | 1.01 ± 0.01 |
| `GC_INITIAL_HEAP_SIZE=10g result-clangsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 4.703 ± 0.040 | 4.640 | 4.760 | 1.00 ± 0.01 |
| `GC_INITIAL_HEAP_SIZE=10g result-gccsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` | 4.766 ± 0.037 | 4.727 | 4.844 | 1.02 ± 0.01 |

Change-Id: I616ca3eab670317587d47b41870d8ac963c019ae

1 files changed, 1 insertions, 5 deletions

diff --git a/mk/libraries.mk b/mk/libraries.mk
index 1bc73d7f7..f9d427b10 100644
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -78,11 +78,7 @@ define build-library
         $(1)_LDFLAGS += -undefined suppress -flat_namespace
       endif
     else
-      ifndef HOST_DARWIN
-        ifndef HOST_CYGWIN
-          $(1)_LDFLAGS += -Wl,-z,defs
-        endif
-      endif
+      # -Wl,-z,defs is broken with sanitizers on Linux/clang at least.
     endif
 
     ifndef HOST_DARWIN