Define a __Docs attribute on classes

Summary:
Define a `<<__Docs("http://example.com/my_project")>>` attribute that allows users to mark the docs homepage for their classes. This makes docs URLs visible to the toolchain, which will enable them to be inherited and shown in the IDE (see later diffs in this stack).

This diff introduces the `__Docs` attribute, adds the field to the AAST and updates the lowerer to set this field.

Ignore hhvm-and-hack-ubuntu which is failing on trunk too.

Reviewed By: hgoldstein

Differential Revision: D37003893

fbshipit-source-id: 131c4174f4d11a36c4f82206a92ad0b9f232d560

Author: Wilfred

hphp/hack/src/annotated_ast/aast.ml

@@ -834,6 +834,7 @@ and ('ex, 'en) class_ = {
   c_namespace: nsenv;
   c_user_attributes: ('ex, 'en) user_attribute list;
   c_file_attributes: ('ex, 'en) file_attribute list;
+  c_docs_url: string option;
   c_enum: enum_ option;
   c_doc_comment: doc_comment option;
   c_emit_id: emit_id option;

hphp/hack/src/hackc/compile/closure_convert.rs

@@ -643,6 +643,7 @@ fn make_closure(
         internal: false,
         // TODO: closures should have the visibility of the module they are defined in
         module: None,
+        docs_url: None,
     };
 
     // TODO(hrust): can we reconstruct fd here from the scratch?

hphp/hack/src/naming/naming.ml

@@ -965,6 +965,7 @@ let rec class_ ctx c =
     N.c_emit_id = c.Aast.c_emit_id;
     N.c_internal = c.Aast.c_internal;
     N.c_module = c.Aast.c_module;
+    N.c_docs_url = c.Aast.c_docs_url;
   }
 
 and user_attributes env attrl =

hphp/hack/src/naming/naming_special_names.ml

@@ -263,6 +263,8 @@ module UserAttributes = struct
 
   let uaDeprecated = "__Deprecated"
 
+  let uaDocs = "__Docs"
+
   let uaEntryPoint = "__EntryPoint"
 
   let uaMemoize = "__Memoize"
@@ -401,6 +403,12 @@ module UserAttributes = struct
                 ^ " If the sampling rate is 100, a notice is only raised every 1/100 calls. If omitted, the default sampling rate is 1 (i.e. all calls raise notices)."
                 ^ " To disable runtime notices, use a sampling rate of 0.";
             } );
+          ( uaDocs,
+            {
+              contexts = [cls];
+              autocomplete = true;
+              doc = "Shows the linked URL when hovering over this type.";
+            } );
           ( uaEntryPoint,
             {
               contexts = [fn];

hphp/hack/src/naming/naming_special_names.rs

@@ -240,6 +240,8 @@ pub mod user_attributes {
 
     pub const DEPRECATED: &str = "__Deprecated";
 
+    pub const DOCS: &str = "__Docs";
+
     pub const ENTRY_POINT: &str = "__EntryPoint";
 
     pub const MEMOIZE: &str = "__Memoize";
@@ -326,6 +328,7 @@ pub mod user_attributes {
             CONSISTENT_CONSTRUCT,
             CONST,
             DEPRECATED,
+            DOCS,
             ENTRY_POINT,
             MEMOIZE,
             MEMOIZE_LSB,

hphp/hack/src/oxidized/aast_visitor/node_impl_gen.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the "hack" directory of this source tree.
 //
-// @generated SignedSource<<7f946d2ac10b9b206329cbc119e54016>>
+// @generated SignedSource<<e1ad32b29dd247f9d61fc11411c303cb>>
 //
 // To regenerate this file, run:
 //   hphp/hack/src/oxidized_regen.sh
@@ -468,6 +468,7 @@ impl<P: Params> Node<P> for Class_<P::Ex, P::En> {
         self.namespace.accept(c, v)?;
         self.user_attributes.accept(c, v)?;
         self.file_attributes.accept(c, v)?;
+        self.docs_url.accept(c, v)?;
         self.enum_.accept(c, v)?;
         self.doc_comment.accept(c, v)?;
         self.emit_id.accept(c, v)?;

hphp/hack/src/oxidized/aast_visitor/node_mut_impl_gen.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the "hack" directory of this source tree.
 //
-// @generated SignedSource<<f0a0d5ca179c975cc43c092d869d512b>>
+// @generated SignedSource<<76a71fa7428d740c66237265628d4493>>
 //
 // To regenerate this file, run:
 //   hphp/hack/src/oxidized_regen.sh
@@ -468,6 +468,7 @@ impl<P: Params> NodeMut<P> for Class_<P::Ex, P::En> {
         self.namespace.accept(c, v)?;
         self.user_attributes.accept(c, v)?;
         self.file_attributes.accept(c, v)?;
+        self.docs_url.accept(c, v)?;
         self.enum_.accept(c, v)?;
         self.doc_comment.accept(c, v)?;
         self.emit_id.accept(c, v)?;

hphp/hack/src/oxidized/gen/aast.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the "hack" directory of this source tree.
 //
-// @generated SignedSource<<71e7d74c1497c94a5c83d21a60f09212>>
+// @generated SignedSource<<2abc1b50c5c8dbc44a30c38131a22352>>
 //
 // To regenerate this file, run:
 //   hphp/hack/src/oxidized_regen.sh
@@ -1338,6 +1338,7 @@ pub struct Class_<Ex, En> {
     pub namespace: Nsenv,
     pub user_attributes: Vec<UserAttribute<Ex, En>>,
     pub file_attributes: Vec<FileAttribute<Ex, En>>,
+    pub docs_url: Option<String>,
     pub enum_: Option<Enum_>,
     pub doc_comment: Option<DocComment>,
     pub emit_id: Option<EmitId>,

hphp/hack/src/oxidized_by_ref/gen/aast.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the "hack" directory of this source tree.
 //
-// @generated SignedSource<<2b43d33ace096c053aa8f91b8a3f7787>>
+// @generated SignedSource<<e8b27d9579188e6f6d400168bcea586a>>
 //
 // To regenerate this file, run:
 //   hphp/hack/src/oxidized_regen.sh
@@ -1696,6 +1696,8 @@ pub struct Class_<'a, Ex, En> {
     #[serde(deserialize_with = "arena_deserializer::arena", borrow)]
     pub file_attributes: &'a [&'a FileAttribute<'a, Ex, En>],
     #[serde(deserialize_with = "arena_deserializer::arena", borrow)]
+    pub docs_url: Option<&'a str>,
+    #[serde(deserialize_with = "arena_deserializer::arena", borrow)]
     pub enum_: Option<&'a Enum_<'a>>,
     #[serde(deserialize_with = "arena_deserializer::arena", borrow)]
     pub doc_comment: Option<&'a DocComment<'a>>,

hphp/hack/src/parser/lowerer/lowerer.rs

@@ -4236,6 +4236,43 @@ fn p_user_attributes<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::User
     Ok(attributes.into_iter().flatten().collect())
 }
 
+/// Extract the URL in `<<__Docs("http://example.com")>>` if the __Docs attribute
+/// is present.
+fn p_docs_url<'a>(attrs: &[ast::UserAttribute], env: &mut Env<'a>) -> Option<String> {
+    let mut url = None;
+
+    for attr in attrs {
+        if attr.name.1 == naming_special_names_rust::user_attributes::DOCS {
+            match attr.params.as_slice() {
+                [param] => match &param.2 {
+                    ast::Expr_::String(s) => match String::from_utf8(s.to_vec()) {
+                        Ok(s) => {
+                            url = Some(s);
+                        }
+                        Err(_) => raise_parsing_error_pos(
+                            &attr.name.0,
+                            env,
+                            "`__Docs` URLs must be valid UTF-8",
+                        ),
+                    },
+                    _ => raise_parsing_error_pos(
+                        &attr.name.0,
+                        env,
+                        "`__Docs` URLs must be a string literal",
+                    ),
+                },
+                _ => {
+                    // Wrong number of arguments to __Docs,
+                    // ignore. The attribute arity checks will tell
+                    // the user their code is wrong.
+                }
+            }
+        }
+    }
+
+    url
+}
+
 fn map_yielding<'a, F, R>(node: S<'a>, env: &mut Env<'a>, p: F) -> Result<(R, bool)>
 where
     F: FnOnce(S<'a>, &mut Env<'a>) -> Result<R>,
@@ -5124,6 +5161,8 @@ fn p_def<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::Def>> {
             let env = env.as_mut();
             let mode = env.file_mode();
             let user_attributes = p_user_attributes(&c.attribute, env)?;
+            let docs_url = p_docs_url(&user_attributes, env);
+
             let kinds = p_kinds(&c.modifiers, env)?;
             let final_ = kinds.has(modifier::FINAL);
             let is_xhp = matches!(
@@ -5186,6 +5225,7 @@ fn p_def<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::Def>> {
                 emit_id: None,
                 internal: kinds.has(modifier::INTERNAL),
                 module: None,
+                docs_url,
             };
             match &c.body.children {
                 ClassishBody(c1) => {
@@ -5385,6 +5425,7 @@ fn p_def<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::Def>> {
                 emit_id: None,
                 internal: kinds.has(modifier::INTERNAL),
                 module: None,
+                docs_url: None,
             })])
         }
 
@@ -5459,6 +5500,7 @@ fn p_def<'a>(node: S<'a>, env: &mut Env<'a>) -> Result<Vec<ast::Def>> {
                 emit_id: None,
                 internal: kinds.has(modifier::INTERNAL),
                 module: None,
+                docs_url: None,
             };
 
             for n in c.elements.syntax_node_to_list_skip_separator() {