Merge #2103

2103: Expand signature help r=matklad a=kjeremy

Signature help using call syntax with tuple structs and enum variants

Fixes #2102.

Co-authored-by: Jeremy Kolb <[email protected]>
Co-authored-by: kjeremy <[email protected]>

2 files changed, 184 insertions, 11 deletions

diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index c95133343..d947ac50c 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -20,24 +20,26 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
     let name_ref = calling_node.name_ref()?;
 
     let analyzer = hir::SourceAnalyzer::new(db, position.file_id, name_ref.syntax(), None);
-    let function = match &calling_node {
+    let (mut call_info, has_self) = match &calling_node {
         FnCallNode::CallExpr(expr) => {
             //FIXME: apply subst
             let (callable_def, _subst) = analyzer.type_of(db, &expr.expr()?)?.as_callable()?;
             match callable_def {
-                hir::CallableDef::Function(it) => it,
-                //FIXME: handle other callables
-                _ => return None,
+                hir::CallableDef::Function(it) => {
+                    (CallInfo::with_fn(db, it), it.data(db).has_self_param())
+                }
+                hir::CallableDef::Struct(it) => (CallInfo::with_struct(db, it)?, false),
+                hir::CallableDef::EnumVariant(it) => (CallInfo::with_enum_variant(db, it)?, false),
             }
         }
-        FnCallNode::MethodCallExpr(expr) => analyzer.resolve_method_call(&expr)?,
+        FnCallNode::MethodCallExpr(expr) => {
+            let function = analyzer.resolve_method_call(&expr)?;
+            (CallInfo::with_fn(db, function), function.data(db).has_self_param())
+        }
     };
 
-    let mut call_info = CallInfo::new(db, function);
-
     // If we have a calling expression let's find which argument we are on
     let num_params = call_info.parameters().len();
-    let has_self = function.data(db).has_self_param();
 
     if num_params == 1 {
         if !has_self {
@@ -115,12 +117,24 @@ impl FnCallNode {
 }
 
 impl CallInfo {
-    fn new(db: &RootDatabase, function: hir::Function) -> Self {
+    fn with_fn(db: &RootDatabase, function: hir::Function) -> Self {
         let signature = FunctionSignature::from_hir(db, function);
 
         CallInfo { signature, active_parameter: None }
     }
 
+    fn with_struct(db: &RootDatabase, st: hir::Struct) -> Option<Self> {
+        let signature = FunctionSignature::from_struct(db, st)?;
+
+        Some(CallInfo { signature, active_parameter: None })
+    }
+
+    fn with_enum_variant(db: &RootDatabase, variant: hir::EnumVariant) -> Option<Self> {
+        let signature = FunctionSignature::from_enum_variant(db, variant)?;
+
+        Some(CallInfo { signature, active_parameter: None })
+    }
+
     fn parameters(&self) -> &[String] {
         &self.signature.parameters
     }
@@ -462,4 +476,77 @@ fn main() {
         assert_eq!(info.active_parameter, Some(1));
         assert_eq!(info.label(), "fn bar(&self, _: u32)");
     }
+
+    #[test]
+    fn works_for_tuple_structs() {
+        let info = call_info(
+            r#"
+/// A cool tuple struct
+struct TS(u32, i32);
+fn main() {
+    let s = TS(0, <|>);
+}"#,
+        );
+
+        assert_eq!(info.label(), "struct TS(u32, i32) -> TS");
+        assert_eq!(info.doc().map(|it| it.into()), Some("A cool tuple struct".to_string()));
+        assert_eq!(info.active_parameter, Some(1));
+    }
+
+    #[test]
+    #[should_panic]
+    fn cant_call_named_structs() {
+        let _ = call_info(
+            r#"
+struct TS { x: u32, y: i32 }
+fn main() {
+    let s = TS(<|>);
+}"#,
+        );
+    }
+
+    #[test]
+    fn works_for_enum_variants() {
+        let info = call_info(
+            r#"
+enum E {
+    /// A Variant
+    A(i32),
+    /// Another
+    B,
+    /// And C
+    C { a: i32, b: i32 }
+}
+
+fn main() {
+    let a = E::A(<|>);
+}
+            "#,
+        );
+
+        assert_eq!(info.label(), "E::A(0: i32)");
+        assert_eq!(info.doc().map(|it| it.into()), Some("A Variant".to_string()));
+        assert_eq!(info.active_parameter, Some(0));
+    }
+
+    #[test]
+    #[should_panic]
+    fn cant_call_enum_records() {
+        let _ = call_info(
+            r#"
+enum E {
+    /// A Variant
+    A(i32),
+    /// Another
+    B,
+    /// And C
+    C { a: i32, b: i32 }
+}
+
+fn main() {
+    let a = E::C(<|>);
+}
+            "#,
+        );
+    }
 }
diff --git a/crates/ra_ide_api/src/display/function_signature.rs b/crates/ra_ide_api/src/display/function_signature.rs
index 43f022ccd..e21f8378d 100644
--- a/crates/ra_ide_api/src/display/function_signature.rs
+++ b/crates/ra_ide_api/src/display/function_signature.rs
@@ -2,7 +2,7 @@
 
 use std::fmt::{self, Display};
 
-use hir::{Docs, Documentation, HasSource};
+use hir::{Docs, Documentation, HasSource, HirDisplay};
 use join_to_string::join;
 use ra_syntax::ast::{self, AstNode, NameOwner, VisibilityOwner};
 use std::convert::From;
@@ -12,9 +12,17 @@ use crate::{
     display::{generic_parameters, where_predicates},
 };
 
+#[derive(Debug)]
+pub enum CallableKind {
+    Function,
+    StructConstructor,
+    VariantConstructor,
+}
+
 /// Contains information about a function signature
 #[derive(Debug)]
 pub struct FunctionSignature {
+    pub kind: CallableKind,
     /// Optional visibility
     pub visibility: Option<String>,
     /// Name of the function
@@ -42,6 +50,79 @@ impl FunctionSignature {
         let ast_node = function.source(db).ast;
         FunctionSignature::from(&ast_node).with_doc_opt(doc)
     }
+
+    pub(crate) fn from_struct(db: &db::RootDatabase, st: hir::Struct) -> Option<Self> {
+        let node: ast::StructDef = st.source(db).ast;
+        match node.kind() {
+            ast::StructKind::Named(_) => return None,
+            _ => (),
+        };
+
+        let params = st
+            .fields(db)
+            .into_iter()
+            .map(|field: hir::StructField| {
+                let ty = field.ty(db);
+                format!("{}", ty.display(db))
+            })
+            .collect();
+
+        Some(
+            FunctionSignature {
+                kind: CallableKind::StructConstructor,
+                visibility: node.visibility().map(|n| n.syntax().text().to_string()),
+                name: node.name().map(|n| n.text().to_string()),
+                ret_type: node.name().map(|n| n.text().to_string()),
+                parameters: params,
+                generic_parameters: generic_parameters(&node),
+                where_predicates: where_predicates(&node),
+                doc: None,
+            }
+            .with_doc_opt(st.docs(db)),
+        )
+    }
+
+    pub(crate) fn from_enum_variant(
+        db: &db::RootDatabase,
+        variant: hir::EnumVariant,
+    ) -> Option<Self> {
+        let node: ast::EnumVariant = variant.source(db).ast;
+        match node.kind() {
+            ast::StructKind::Named(_) | ast::StructKind::Unit => return None,
+            _ => (),
+        };
+
+        let parent_name = match variant.parent_enum(db).name(db) {
+            Some(name) => name.to_string(),
+            None => "missing".into(),
+        };
+
+        let name = format!("{}::{}", parent_name, variant.name(db).unwrap());
+
+        let params = variant
+            .fields(db)
+            .into_iter()
+            .map(|field: hir::StructField| {
+                let name = field.name(db);
+                let ty = field.ty(db);
+                format!("{}: {}", name, ty.display(db))
+            })
+            .collect();
+
+        Some(
+            FunctionSignature {
+                kind: CallableKind::VariantConstructor,
+                visibility: None,
+                name: Some(name),
+                ret_type: None,
+                parameters: params,
+                generic_parameters: vec![],
+                where_predicates: vec![],
+                doc: None,
+            }
+            .with_doc_opt(variant.docs(db)),
+        )
+    }
 }
 
 impl From<&'_ ast::FnDef> for FunctionSignature {
@@ -59,6 +140,7 @@ impl From<&'_ ast::FnDef> for FunctionSignature {
         }
 
         FunctionSignature {
+            kind: CallableKind::Function,
             visibility: node.visibility().map(|n| n.syntax().text().to_string()),
             name: node.name().map(|n| n.text().to_string()),
             ret_type: node
@@ -81,7 +163,11 @@ impl Display for FunctionSignature {
         }
 
         if let Some(name) = &self.name {
-            write!(f, "fn {}", name)?;
+            match self.kind {
+                CallableKind::Function => write!(f, "fn {}", name)?,
+                CallableKind::StructConstructor => write!(f, "struct {}", name)?,
+                CallableKind::VariantConstructor => write!(f, "{}", name)?,
+            }
         }
 
         if !self.generic_parameters.is_empty() {