Set allow_empty on unknown globs

This means that if people build with
`--incompatible_disallow_empty_glob` things will still work.

crate_universe/src/context.rs

@@ -291,7 +291,7 @@ mod test {
     }
 
     #[test]
-    fn seralization() {
+    fn serialization() {
         let context = mock_context_aliases();
 
         // Seralize and deseralize the context object

crate_universe/src/rendering.rs

@@ -153,6 +153,7 @@ impl Renderer {
         let mut exports_files = ExportsFiles {
             paths: BTreeSet::from(["cargo-bazel.json".to_owned(), "defs.bzl".to_owned()]),
             globs: Glob {
+                allow_empty: true,
                 include: BTreeSet::from(["*.bazel".to_owned()]),
                 exclude: BTreeSet::new(),
             },
@@ -165,6 +166,7 @@ impl Renderer {
         let filegroup = Filegroup {
             name: "srcs".to_owned(),
             srcs: Glob {
+                allow_empty: true,
                 include: BTreeSet::from(["*.bazel".to_owned(), "*.bzl".to_owned()]),
                 exclude: BTreeSet::new(),
             },
@@ -873,6 +875,7 @@ fn make_data(
 
     Data {
         glob: Glob {
+            allow_empty: true,
             include: glob,
             exclude: COMMON_GLOB_EXCLUDES
                 .iter()

crate_universe/src/utils/starlark/glob.rs

@@ -7,19 +7,21 @@ use serde::ser::{Serialize, SerializeStruct, Serializer};
 
 #[derive(Debug, Default, PartialEq, Eq, PartialOrd, Ord, Clone)]
 pub struct Glob {
+    pub allow_empty: bool,
     pub include: BTreeSet<String>,
     pub exclude: BTreeSet<String>,
 }
 
 impl Glob {
     pub fn new_rust_srcs() -> Self {
         Self {
+            allow_empty: false,
             include: BTreeSet::from(["**/*.rs".to_owned()]),
             exclude: BTreeSet::new(),
         }
     }
 
-    pub fn is_empty(&self) -> bool {
+    pub fn has_any_include(&self) -> bool {
         self.include.is_empty()
         // Note: self.exclude intentionally not considered. A glob is empty if
         // there are no included globs. A glob cannot have only excludes.
@@ -31,16 +33,17 @@ impl Serialize for Glob {
     where
         S: Serializer,
     {
-        if self.exclude.is_empty() {
-            // Serialize as glob([...]).
-            serializer.serialize_newtype_struct("glob", &self.include)
-        } else {
-            // Serialize as glob(include = [...], exclude = [...]).
-            let mut call = serializer.serialize_struct("glob", 2)?;
-            call.serialize_field("include", &self.include)?;
+        let has_exclude = !self.exclude.is_empty();
+        let len = 2 + if has_exclude { 1 } else { 0 };
+
+        // Serialize as glob(allow_empty = False, include = [...], exclude = [...]).
+        let mut call = serializer.serialize_struct("glob", len)?;
+        call.serialize_field("allow_empty", &self.allow_empty)?;
+        call.serialize_field("include", &self.include)?;
+        if has_exclude {
             call.serialize_field("exclude", &self.exclude)?;
-            call.end()
         }
+        call.end()
     }
 }
 
@@ -68,6 +71,9 @@ impl<'de> Visitor<'de> for GlobVisitor {
         A: SeqAccess<'de>,
     {
         Ok(Glob {
+            // At time of writing the default value of allow_empty is true.
+            // We may want to change this if the default changes in Bazel.
+            allow_empty: true,
             include: BTreeSet::deserialize(SeqAccessDeserializer::new(seq))?,
             exclude: BTreeSet::new(),
         })
@@ -78,14 +84,22 @@ impl<'de> Visitor<'de> for GlobVisitor {
     where
         A: MapAccess<'de>,
     {
+        fn default_true() -> bool {
+            true
+        }
+
         #[derive(serde::Deserialize)]
         struct GlobMap {
+            #[serde(default = "default_true")]
+            allow_empty: bool,
             include: BTreeSet<String>,
+            #[serde(default)]
             exclude: BTreeSet<String>,
         }
 
         let glob_map = GlobMap::deserialize(MapAccessDeserializer::new(map))?;
         Ok(Glob {
+            allow_empty: glob_map.allow_empty,
             include: glob_map.include,
             exclude: glob_map.exclude,
         })

crate_universe/src/utils/starlark/serialize.rs

@@ -130,7 +130,7 @@ impl Serialize for ExportsFiles {
 
 impl Data {
     pub fn is_empty(&self) -> bool {
-        self.glob.is_empty() && self.select.is_empty()
+        self.glob.has_any_include() && self.select.is_empty()
     }
 }
 
@@ -140,10 +140,10 @@ impl Serialize for Data {
         S: Serializer,
     {
         let mut plus = serializer.serialize_tuple_struct("+", MULTILINE)?;
-        if !self.glob.is_empty() {
+        if !self.glob.has_any_include() {
             plus.serialize_field(&self.glob)?;
         }
-        if !self.select.is_empty() || self.glob.is_empty() {
+        if !self.select.is_empty() || self.glob.has_any_include() {
             plus.serialize_field(&self.select)?;
         }
         plus.end()

examples/.bazelrc

@@ -18,6 +18,9 @@ build:clippy --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/android/.bazelrc

@@ -8,3 +8,6 @@ build --fat_apk_cpu=arm64-v8a --android_crosstool_top=@androidndk//:toolchain
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/bzlmod/all_crate_deps/.bazelrc

@@ -4,3 +4,6 @@ startup --windows_enable_symlinks
 build:windows --enable_runfiles
 
 build --experimental_enable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/bzlmod/cross_compile/.bazelrc

@@ -1 +1,4 @@
 build --experimental_enable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/bzlmod/hello_world/.bazelrc

@@ -4,3 +4,6 @@ startup --windows_enable_symlinks
 build:windows --enable_runfiles
 
 build --experimental_enable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/cargo_manifest_dir/external_crate/.bazelrc

@@ -1 +1,4 @@
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/crate_universe/.bazelrc

@@ -22,6 +22,9 @@ build --nolegacy_external_runfiles
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/crate_universe/cargo_aliases/.bazelrc

@@ -17,6 +17,9 @@ build:strict --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/crate_universe/cargo_remote/.bazelrc

@@ -17,6 +17,9 @@ build:strict --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/crate_universe/cargo_workspace/.bazelrc

@@ -17,6 +17,9 @@ build:strict --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/crate_universe/multi_package/.bazelrc

@@ -17,6 +17,9 @@ build:strict --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/crate_universe/no_cargo_manifests/.bazelrc

@@ -17,6 +17,9 @@ build:strict --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/crate_universe_unnamed/.bazelrc

@@ -18,6 +18,9 @@ build:clippy --output_groups=+clippy_checks
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc

examples/ios/.bazelrc

@@ -11,3 +11,6 @@ build --host_crosstool_top=@local_config_apple_cc//:toolchain
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/ios_build/.bazelrc

@@ -11,3 +11,6 @@ build --host_crosstool_top=@local_config_apple_cc//:toolchain
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

examples/nix_cross_compiling/.bazelrc

@@ -4,6 +4,9 @@ build --incompatible_strict_action_env
 build --action_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
 build --incompatible_enable_cc_toolchain_resolution=true
 
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob
+
 # Require Platform Transitions
 ## This works by setting the targte platform to an invalid platform
 ## and each `x_binary()` and `x_library()` rule unfortunately needs

examples/zig_cross_compiling/.bazelrc

@@ -8,3 +8,6 @@ build --incompatible_enable_cc_toolchain_resolution
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

test/cc_common_link/.bazelrc

@@ -1 +1,4 @@
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

test/cc_common_link/with_global_alloc/.bazelrc

@@ -1 +1,4 @@
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob

test/no_std/.bazelrc

@@ -1 +1,4 @@
 common --noenable_bzlmod
+
+# This isn't currently the defaut in Bazel, but we enable it to test we'll be ready if/when it flips.
+build --incompatible_disallow_empty_glob