Revert "bintools-wrapper: skip dynamic linker for static binaries"

This reverts commit ccfd26ef14.

These toolchain changes are too problematic, so reverting for now; see
https://github.com/NixOS/nixpkgs/pull/107086#issuecomment-749196366

pkgs/build-support/bintools-wrapper/add-flags.sh

@@ -3,7 +3,6 @@ var_templates_list=(
     NIX_IGNORE_LD_THROUGH_GCC
     NIX_LDFLAGS
     NIX_LDFLAGS_BEFORE
-    NIX_DYNAMIC_LINKER
     NIX_LDFLAGS_AFTER
     NIX_LDFLAGS_HARDEN
     NIX_HARDENING_ENABLE
@@ -26,10 +25,6 @@ if [ -e @out@/nix-support/libc-ldflags ]; then
     NIX_LDFLAGS_@suffixSalt@+=" $(< @out@/nix-support/libc-ldflags)"
 fi
 
-if [ -z "$NIX_DYNAMIC_LINKER_@suffixSalt@" ] && [ -e @out@/nix-support/dynamic-linker ]; then
-    NIX_DYNAMIC_LINKER_@suffixSalt@="$(< @out@/nix-support/dynamic-linker)"
-fi
-
 if [ -e @out@/nix-support/libc-ldflags-before ]; then
     NIX_LDFLAGS_BEFORE_@suffixSalt@="$(< @out@/nix-support/libc-ldflags-before) $NIX_LDFLAGS_BEFORE_@suffixSalt@"
 fi

pkgs/build-support/bintools-wrapper/default.nix

@@ -243,7 +243,13 @@ stdenv.mkDerivation {
         if [ -e ${libc_lib}/lib/32/ld-linux.so.2 ]; then
           echo ${libc_lib}/lib/32/ld-linux.so.2 > $out/nix-support/dynamic-linker-m32
         fi
-      '') + ''
+      ''
+      # The dynamic linker is passed in `ldflagsBefore' to allow
+      # explicit overrides of the dynamic linker by callers to ld
+      # (the *last* value counts, so ours should come first).
+      + ''
+        echo -dynamic-linker "$dynamicLinker" >> $out/nix-support/libc-ldflags-before
+    '') + ''
       fi
     '')
 

pkgs/build-support/bintools-wrapper/ld-wrapper.sh

@@ -20,7 +20,6 @@ if [ -z "${NIX_BINTOOLS_WRAPPER_FLAGS_SET_@suffixSalt@:-}" ]; then
     source @out@/nix-support/add-flags.sh
 fi
 
-setDynamicLinker=1
 
 # Optionally filter out paths not refering to the store.
 expandResponseParams "$@"
@@ -48,11 +47,6 @@ if [[ "${NIX_ENFORCE_PURITY:-}" = 1 && -n "${NIX_STORE:-}"
             # Our ld is not built with sysroot support (Can we fix that?)
             :
         else
-            if [[ "$p" = -static || "$p" = -static-pie ]]; then
-                # Using a dynamic linker for static binaries can lead to crashes.
-                # This was observed for rust binaries.
-                setDynamicLinker=0
-            fi
             rest+=("$p")
         fi
         n+=1
@@ -69,11 +63,6 @@ extraBefore=(${hardeningLDFlags[@]+"${hardeningLDFlags[@]}"})
 if [ -z "${NIX_LDFLAGS_SET_@suffixSalt@:-}" ]; then
     extraAfter+=($NIX_LDFLAGS_@suffixSalt@)
     extraBefore+=($NIX_LDFLAGS_BEFORE_@suffixSalt@)
-    # By adding dynamic linker to extraBefore we allow the users set their
-    # own dynamic linker as NIX_LD_FLAGS will override earlier set flags
-    if [ "$setDynamicLinker" = 1 ]; then
-        extraBefore+=("-dynamic-linker" "$NIX_DYNAMIC_LINKER_@suffixSalt@")
-    fi
 fi
 
 extraAfter+=($NIX_LDFLAGS_AFTER_@suffixSalt@)
@@ -145,7 +134,7 @@ then
     done
 fi
 
-if [[ "$link32" = "0" && "$setDynamicLinker" = 1 && -e "@out@/nix-support/dynamic-linker-m32" ]]; then
+if [ -e "@out@/nix-support/dynamic-linker-m32" ] && (( "$link32" )); then
     # We have an alternate 32-bit linker and we're producing a 32-bit ELF, let's
     # use it.
     extraAfter+=(