bear: fix

The previous build system patch was incomplete and left the `wrapper.d`
directory empty, leaving Bear unable to pick up any build commands
at all and breaking the functional test suite, which we also weren't
running. Switch to overriding CMake flags instead and add the patches
and dependencies necessary to get the functional tests running to
prevent a future regression.

I've checked that the instructions in Nix's
`doc/manual/src/contributing/hacking.md` work after this change,
which is what started this yak shave in the first place.

pkgs/development/tools/build-managers/bear/default.nix

···
 , zlib
 , sqlite
 , re2
+, lit
+, python3
+, coreutils
 }:
 
 stdenv.mkDerivation rec {
···
     hash = "sha256-1nZPzgLWcmaRkOUXdm16IW2Nw/p1w8GBGEfZX/v+En0=";
   };
 
-  nativeBuildInputs = [ cmake pkg-config ];
+  nativeBuildInputs = [
+    cmake
+    pkg-config
+
+    # Used for functional tests, which run during buildPhase.
+    lit
+    python3
+  ];
 
   buildInputs = [
     grpc
···
     re2
   ];
 
+  cmakeFlags = [
+    # Build system and generated files concatenate install prefix and
+    # CMAKE_INSTALL_{BIN,LIB}DIR, which breaks if these are absolute paths.
+    "-DCMAKE_INSTALL_BINDIR=bin"
+    "-DCMAKE_INSTALL_LIBDIR=lib"
+  ];
+
   patches = [
-    # Default libexec would be set to /nix/store/*-bear//nix/store/*-bear/libexec/...
-    ./no-double-relative.patch
+    # Fix toolchain environment variable handling and the Darwin SIP check.
+    ./fix-functional-tests.patch
   ];
+
+  postPatch = ''
+    patchShebangs test/bin
+
+    # /usr/bin/env is used in test commands and embedded scripts.
+    find test -name '*.sh' \
+      -exec sed -ie 's|/usr/bin/env|${coreutils}/bin/env|g' {} +
+  '';
+
+  # Functional tests use loopback networking.
+  __darwinAllowLocalNetworking = true;
 
   meta = with lib; {
     broken = stdenv.isDarwin;

pkgs/development/tools/build-managers/bear/fix-functional-tests.patch

···
+diff --git a/test/lit.cfg b/test/lit.cfg
+index 118c979..b69fecc 100644
+--- a/test/lit.cfg
++++ b/test/lit.cfg
+@@ -207,13 +207,8 @@ def is_preload_disabled():
+     if is_windows:
+         return True
+     elif sys.platform == 'darwin':
+-        command = ['csrutil', 'status']
+-        pattern = re.compile(r'System Integrity Protection status:\s+enabled')
+-        try:
+-            output = subprocess.check_output(command, stderr=subprocess.STDOUT)
+-            return any(pattern.match(line) for line in output.decode('utf-8').splitlines())
+-        except (OSError, subprocess.CalledProcessError):
+-            return False
++        # csrutil(8) isn't available in the Nix build sandbox.
++        return True
+     else:
+         return False
+ 
+@@ -221,6 +216,11 @@ def is_preload_disabled():
+ if not is_preload_disabled():
+     config.available_features.add('preload')
+ 
++# Preserve the variables required for the Nix toolchain wrappers.
++for var, value in os.environ.items():
++    if var.startswith('NIX_'):
++        config.environment[var] = value
++
+ print(config.substitutions)
+ print(config.environment)
+ print(config.available_features)

pkgs/development/tools/build-managers/bear/no-double-relative.patch

···
-diff --git a/source/config.h.in b/source/config.h.in
-index 6b659c2..f7bdf22 100644
---- a/source/config.h.in
-+++ b/source/config.h.in
-@@ -108,8 +108,8 @@ namespace cmd {
-     }
- 
-     namespace wrapper {
--        constexpr char DEFAULT_PATH[] = "@ROOT_INSTALL_PREFIX@/@CMAKE_INSTALL_LIBDIR@/bear/wrapper";
--        constexpr char DEFAULT_DIR_PATH[] = "@ROOT_INSTALL_PREFIX@/@CMAKE_INSTALL_LIBDIR@/bear/wrapper.d";
-+        constexpr char DEFAULT_PATH[] = "@CMAKE_INSTALL_LIBDIR@/bear/wrapper";
-+        constexpr char DEFAULT_DIR_PATH[] = "@CMAKE_INSTALL_LIBDIR@/bear/wrapper.d";
- 
-         constexpr char FLAG_VERBOSE[] = "--verbose";
-         constexpr char FLAG_DESTINATION[] = "--destination";
-@@ -134,9 +134,9 @@ namespace cmd {
-         // And use the `libexec.so` path default value with a single path,
-         // that matches both. (The match can be achieved by the $LIB token
-         // expansion from the dynamic loader. See `man ld.so` for more.)
--        constexpr char DEFAULT_PATH[] = "@ROOT_INSTALL_PREFIX@/$LIB/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
-+        constexpr char DEFAULT_PATH[] = "$LIB/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
- #else
--        constexpr char DEFAULT_PATH[] = "@ROOT_INSTALL_PREFIX@/@CMAKE_INSTALL_LIBDIR@/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
-+        constexpr char DEFAULT_PATH[] = "@CMAKE_INSTALL_LIBDIR@/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
- #endif
-         constexpr char KEY_REPORTER[] = "INTERCEPT_REPORT_COMMAND";
-         constexpr char KEY_DESTINATION[] = "INTERCEPT_REPORT_DESTINATION";