Merge 20127a37f5 into 0e1323c041

src/nix-build/nix-build.cc

@@ -473,8 +473,11 @@ static void main_nix_build(int argc, char * * argv)
                 shellDrv = bashDrv;
 
             } catch (Error & e) {
-                logError(e.info());
-                notice("will use bash from your environment");
+                // in a shebang, it doesn't matter which bash we use since we immediately execute the interpreter
+                if (!inShebang) {
+                    logErrorInfo(lvlInfo, e.info());
+                    printInfo("Cannot access '(import <nixpkgs> {}).bashInteractive'; falling back to bash from your environment.");
+                }
                 shell = "bash";
             }
         }
@@ -612,9 +615,8 @@ static void main_nix_build(int argc, char * * argv)
                 + structuredAttrsRC +
                 "\n[ -e $stdenv/setup ] && source $stdenv/setup; "
                 "%3%"
-                "PATH=%4%:\"$PATH\"; "
-                "SHELL=%5%; "
-                "BASH=%5%; "
+                "SHELL=%4%; "
+                "BASH=%4%; "
                 "set +e; "
                 R"s([ -n "$PS1" -a -z "$NIX_SHELL_PRESERVE_PROMPT" ] && )s" +
                 (isRootUser()
@@ -623,13 +625,12 @@ static void main_nix_build(int argc, char * * argv)
                 "if [ \"$(type -t runHook)\" = function ]; then runHook shellHook; fi; "
                 "unset NIX_ENFORCE_PURITY; "
                 "shopt -u nullglob; "
-                "unset TZ; %6%"
+                "unset TZ; %5%"
                 "shopt -s execfail;"
-                "%7%",
+                "%6%",
                 shellEscape(tmpDir.path().string()),
                 (pure ? "" : "p=$PATH; "),
                 (pure ? "" : "PATH=$PATH:$p; unset p; "),
-                shellEscape(dirOf(*shell)),
                 shellEscape(*shell),
                 (getenv("TZ") ? (std::string("export TZ=") + shellEscape(getenv("TZ")) + "; ") : ""),
                 envCommand);

tests/functional/config.nix.in

@@ -10,7 +10,7 @@ in
 rec {
   shell = "@bash@";
 
-  path = "@coreutils@";
+  path = "@coreutils@:${dirOf shell}";
 
   system = "@system@";
 

tests/functional/dummy-build-shells/1-shell

@@ -0,0 +1 @@
+echo "1"

tests/functional/dummy-build-shells/2-nixpkgs.nix

@@ -0,0 +1,11 @@
+args:
+let
+  pkgs = import ../shell.nix args;
+in
+{
+  bashInteractive = pkgs.runCommand "bash" { } ''
+    mkdir -p $out/bin
+    echo "echo 2" > $out/bin/bash
+    chmod +x $out/bin/bash
+  '';
+}

tests/functional/nix-shell.sh

@@ -196,6 +196,36 @@ $TEST_ROOT/issue-11892/shebangscript \
   | tee /dev/stderr \
   | grepQuiet "ok baz11892"
 
+(
+    # Test the prioritization of build shells
+    export NIX_BUILD_SHELL="$PWD/dummy-build-shells/1-shell"
+    export NIX_PATH="nixpkgs=$PWD/dummy-build-shells/2-nixpkgs.nix"
+
+    # 1. $NIX_BUILD_SHELL
+    # "echo 3" will not run because the bash used is provied by 1-shell
+    output=$(nix-shell --pure "$shellDotNix" -A shellDrv --run "echo 3")
+    [ "$output" = "1" ]
+
+    # 2. (import <nixpkgs> {}).bashInteractive
+    # "echo 3" will not be run because the bash used is provided by 2-nixpkgs
+    unset NIX_BUILD_SHELL
+    output=$(nix-shell --pure "$shellDotNix" -A shellDrv --run "echo 3")
+    [ "$output" = "2" ]
+
+    # 3. bash from $PATH
+    # NOTE: we should really test this by overwriting $PATH and passing --keep
+    # PATH to nix-shell, but the mkDerivation in config.nix will overwrite
+    # whatever PATH we give here so we'll use what's defined in config.nix
+    # (actual bash) as our third example with --run 'echo 3'
+    unset NIX_PATH
+    output=$(nix-shell --pure "$shellDotNix" -A shellDrv --run 'echo 3')
+    [ "$output" = "3" ]
+
+    # 4. once we are in the nix-shell, `bash` should be whatever is provided by
+    # the derivation
+    output=$(nix-shell --pure "$shellDotNix" -A shellDrvFakeBash4 --run 'bash -e "echo 5"')
+    [ "$output" = "4" ]
+)
 
 #####################
 # Flake equivalents #

tests/functional/shell.nix

@@ -84,6 +84,13 @@ let
       '';
     };
 
+    shellDrvFakeBash4 = mkDerivation {
+      name = "shellDrvFakeBash4";
+      builder = "/does/not/exist";
+      inherit stdenv;
+      PATH = "${fakeBash4}/bin:${path}";
+    };
+
     # Used by nix-shell -p
     runCommand =
       name: args: buildCommand:
@@ -120,6 +127,12 @@ let
       chmod a+rx $out/bin/ruby
     '';
 
+    fakeBash4 = runCommand "fakeBash4" { } ''
+      mkdir -p $out/bin
+      echo 'echo 4' > $out/bin/bash
+      chmod a+rx $out/bin/bash
+    '';
+
     inherit (cfg) shell;
 
     callPackage = f: args: f (pkgs // args);