ir: Add an option to generate an empty, default constructor for tagged enums.

emilio · emilio · commit b2efcc4051ef · 2019-08-25T17:05:22.000+02:00
This allows to clean up a pattern that has been showing up lately, see occurrences of: https://searchfox.org/mozilla-central/rev/9775cca0a10a9b5c5f4e15c8f7b3eff5bf91bbd0/servo/ports/geckolib/cbindgen.toml#329
diff --git a/docs.md b/docs.md
@@ -270,6 +270,7 @@ The rest are just local overrides for the same options found in the cbindgen.tom
 * derive-tagged-enum-destructor
 * derive-tagged-enum-copy-constructor
 * prefix-with-name
+* private-default-tagged-enum-constructor
 
 
 
@@ -703,6 +704,14 @@ derive_tagged_enum_destructor = false
 # default: false
 derive_tagged_enum_copy_constructor = false
 
+# Whether enums with fields should generate an empty, private destructor.
+# This allows the auto-generated constructor functions to compile, if there are
+# non-trivially constructible members. This falls in the same family of
+# dangerousness as `derive_tagged_enum_copy_constructor` and co.
+#
+# default: false
+private_default_tagged_enum_constructor = false
+
 
 
 
diff --git a/src/bindgen/config.rs b/src/bindgen/config.rs
@@ -400,6 +400,9 @@ pub struct EnumConfig {
     pub derive_tagged_enum_destructor: bool,
     /// Whether to generate copy-constructors of tagged enums.
     pub derive_tagged_enum_copy_constructor: bool,
+    /// Whether to generate empty, private default-constructors for tagged
+    /// enums.
+    pub private_default_tagged_enum_constructor: bool,
 }
 
 impl EnumConfig {
@@ -439,6 +442,15 @@ impl EnumConfig {
         }
         self.derive_tagged_enum_copy_constructor
     }
+    pub(crate) fn private_default_tagged_enum_constructor(
+        &self,
+        annotations: &AnnotationSet,
+    ) -> bool {
+        if let Some(x) = annotations.bool("private-default-tagged-enum-constructor") {
+            return x;
+        }
+        self.private_default_tagged_enum_constructor
+    }
 }
 
 /// Settings to apply to generated constants.
diff --git a/src/bindgen/ir/enumeration.rs b/src/bindgen/ir/enumeration.rs
@@ -890,6 +890,22 @@ impl Source for Enum {
                 }
             }
 
+            if config.language == Language::Cxx
+                && config
+                    .enumeration
+                    .private_default_tagged_enum_constructor(&self.annotations)
+            {
+                out.new_line();
+                out.new_line();
+                write!(out, "private:");
+                out.new_line();
+                write!(out, "{}()", self.export_name);
+                out.open_brace();
+                out.close_brace(false);
+                write!(out, "public:");
+                out.new_line();
+            }
+
             if config.language == Language::Cxx
                 && config
                     .enumeration
diff --git a/template.toml b/template.toml
@@ -102,6 +102,7 @@ derive_mut_casts = false
 # cast_assert_name = "ASSERT"
 derive_tagged_enum_destructor = false
 derive_tagged_enum_copy_constructor = false
+private_default_tagged_enum_constructor = false
 
 
 

Original file line number	Diff line number	Diff line change
`@@ -400,6 +400,9 @@ pub struct EnumConfig {`
`400`	`400`	`pub derive_tagged_enum_destructor: bool,`
`401`	`401`	`/// Whether to generate copy-constructors of tagged enums.`
`402`	`402`	`pub derive_tagged_enum_copy_constructor: bool,`
	`403`	`+ /// Whether to generate empty, private default-constructors for tagged`
	`404`	`+ /// enums.`
	`405`	`+ pub private_default_tagged_enum_constructor: bool,`
`403`	`406`	`}`
`404`	`407`
`405`	`408`	`impl EnumConfig {`
`@@ -439,6 +442,15 @@ impl EnumConfig {`
`439`	`442`	`}`
`440`	`443`	`self.derive_tagged_enum_copy_constructor`
`441`	`444`	`}`
	`445`	`+ pub(crate) fn private_default_tagged_enum_constructor(`
	`446`	`+ &self,`
	`447`	`+ annotations: &AnnotationSet,`
	`448`	`+ ) -> bool {`
	`449`	`+ if let Some(x) = annotations.bool("private-default-tagged-enum-constructor") {`
	`450`	`+ return x;`
	`451`	`+ }`
	`452`	`+ self.private_default_tagged_enum_constructor`
	`453`	`+ }`
`442`	`454`	`}`
`443`	`455`
`444`	`456`	`/// Settings to apply to generated constants.`