Windows: Bazel no longer fails if MSYS is missing

Fixes bazelbuild#6462

Change-Id: I6792b6d3be7ea0d31154a4c3cb9983c601689301

src/main/cpp/blaze_util_windows.cc

@@ -1447,14 +1447,16 @@ static string LocateBash() {
   }
 
   string result = GetBinaryFromPath("bash.exe");
-  if (result.empty()) {
-    BAZEL_LOG(ERROR) << "bash.exe not found on PATH";
-  }
+//  if (result.empty()) {
+//    BAZEL_LOG(ERROR) << "bash.exe not found on PATH";
+//  }
   return result;
 }
 
 void DetectBashOrDie() {
-  if (!blaze::GetEnv("BAZEL_SH").empty()) return;
+  if (!blaze::GetEnv("BAZEL_SH").empty()) {
+    return;
+  }
 
   uint64_t start = blaze::GetMillisecondsMonotonic();
 
@@ -1466,18 +1468,18 @@ void DetectBashOrDie() {
   if (!bash.empty()) {
     // Set process environment variable.
     blaze::SetEnv("BAZEL_SH", bash);
-  } else {
-    // TODO(bazel-team) should this be printed to stderr? If so, it should use
-    // BAZEL_LOG(ERROR)
-    printf(
-        "Bazel on Windows requires MSYS2 Bash, but we could not find it.\n"
-        "If you do not have it installed, you can install MSYS2 from\n"
-        "       http://repo.msys2.org/distrib/msys2-x86_64-latest.exe\n"
-        "\n"
-        "If you already have it installed but Bazel cannot find it,\n"
-        "set BAZEL_SH environment variable to its location:\n"
-        "       set BAZEL_SH=c:\\path\\to\\msys2\\usr\\bin\\bash.exe\n");
-    exit(1);
+//  } else {
+//    // TODO(bazel-team) should this be printed to stderr? If so, it should use
+//    // BAZEL_LOG(ERROR)
+//    printf(
+//        "Bazel on Windows requires MSYS2 Bash, but we could not find it.\n"
+//        "If you do not have it installed, you can install MSYS2 from\n"
+//        "       http://repo.msys2.org/distrib/msys2-x86_64-latest.exe\n"
+//        "\n"
+//        "If you already have it installed but Bazel cannot find it,\n"
+//        "set BAZEL_SH environment variable to its location:\n"
+//        "       set BAZEL_SH=c:\\path\\to\\msys2\\usr\\bin\\bash.exe\n");
+//    exit(1);
   }
 }
 

src/main/java/com/google/devtools/build/lib/analysis/ShellConfiguration.java

@@ -32,11 +32,11 @@
 
 /** A configuration fragment that tells where the shell is. */
 public class ShellConfiguration extends BuildConfiguration.Fragment {
-  private static final ImmutableMap<OS, PathFragment> OS_SPECIFIC_SHELL =
-      ImmutableMap.<OS, PathFragment>builder()
-          .put(OS.WINDOWS, PathFragment.create("c:/tools/msys64/usr/bin/bash.exe"))
-          .put(OS.FREEBSD, PathFragment.create("/usr/local/bin/bash"))
-          .build();
+//  private static final ImmutableMap<OS, PathFragment> OS_SPECIFIC_SHELL =
+//      ImmutableMap.<OS, PathFragment>builder()
+//          .put(OS.WINDOWS, PathFragment.create("c:/tools/msys64/usr/bin/bash.exe"))
+//          .put(OS.FREEBSD, PathFragment.create("/usr/local/bin/bash"))
+//          .build();
 
   private final PathFragment shellExecutable;
   private final boolean useShBinaryStubScript;
@@ -135,8 +135,9 @@ public static PathFragment determineShellExecutable(
       // TODO(ulfjack): instead of using the OS Bazel runs on, we need to use the exec platform,
       // which may be different for remote execution. For now, this can be overridden with
       // --shell_executable, so at least there's a workaround.
-      PathFragment result = OS_SPECIFIC_SHELL.get(os);
-      return result != null ? result : defaultShell;
+//      PathFragment result = OS_SPECIFIC_SHELL.get(os);
+//      return result != null ? result : defaultShell;
+      return defaultShell;
     }
 
     @Override

src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java

@@ -133,13 +133,13 @@ public StrictActionEnvOptions getHost() {
     }
   }
 
-  private static final PathFragment FALLBACK_SHELL = PathFragment.create("/bin/bash");
+  // private static final PathFragment FALLBACK_SHELL = PathFragment.create("/bin/bash");
 
   public static final ShellExecutableProvider SHELL_EXECUTABLE = (BuildOptions options) ->
       ShellConfiguration.Loader.determineShellExecutable(
           OS.getCurrent(),
           options.get(ShellConfiguration.Options.class),
-          FALLBACK_SHELL);
+          null); // FALLBACK_SHELL);
 
   public static final ActionEnvironmentProvider SHELL_ACTION_ENV = (BuildOptions options) -> {
     boolean strictActionEnv = options.get(StrictActionEnvOptions.class).useStrictActionEnv;