Merge #1796

1796: Support completion for macros r=matklad a=uHOOCCOOHu

This is based on #1795 , and fixes #1727 

Also prettify hover text of macros.

Some screenshorts below:

Completion in item place.
<img width="416" alt="Screenshot_20190910_134056" src="https://user-images.githubusercontent.com/14816024/64587159-fa72da00-d3d0-11e9-86bb-c98f169ec08d.png">

After pressing `tab`.
<img width="313" alt="Screenshot_20190910_134111" src="https://user-images.githubusercontent.com/14816024/64587160-fa72da00-d3d0-11e9-9464-21e3f6957bd7.png">

Complete macros from `std`.
<img width="588" alt="Screenshot_20190910_134147" src="https://user-images.githubusercontent.com/14816024/64587161-fb0b7080-d3d0-11e9-866e-5161f0d1b546.png">

Hover text.
<img width="521" alt="Screenshot_20190910_134242" src="https://user-images.githubusercontent.com/14816024/64587162-fb0b7080-d3d0-11e9-8f09-ad17e3f6702a.png">



Co-authored-by: uHOOCCOOHu <[email protected]>

1 files changed, 50 insertions, 0 deletions

diff --git a/crates/ra_ide_api/src/completion/complete_macro_in_item_position.rs b/crates/ra_ide_api/src/completion/complete_macro_in_item_position.rs
new file mode 100644
index 000000000..708dc9777
--- /dev/null
+++ b/crates/ra_ide_api/src/completion/complete_macro_in_item_position.rs
@@ -0,0 +1,50 @@
+use crate::completion::{CompletionContext, Completions};
+
+pub(super) fn complete_macro_in_item_position(acc: &mut Completions, ctx: &CompletionContext) {
+    // Show only macros in top level.
+    if ctx.is_new_item {
+        for (name, res) in ctx.analyzer.all_names(ctx.db) {
+            if res.get_macros().is_some() {
+                acc.add_resolution(ctx, name.to_string(), &res.only_macros());
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::{do_completion, CompletionItem, CompletionKind};
+    use insta::assert_debug_snapshot;
+
+    fn do_reference_completion(code: &str) -> Vec<CompletionItem> {
+        do_completion(code, CompletionKind::Reference)
+    }
+
+    #[test]
+    fn completes_macros_as_item() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /main.rs
+                macro_rules! foo {
+                    () => {}
+                }
+
+                fn foo() {}
+
+                <|>
+                "
+            ),
+            @r##"[
+    CompletionItem {
+        label: "foo",
+        source_range: [46; 46),
+        delete: [46; 46),
+        insert: "foo!",
+        kind: Macro,
+        detail: "macro_rules! foo",
+    },
+]"##
+        );
+    }
+}