Auto merge of #17523 - wada314:master, r=Veykril

Add an option to use "::" for the external crate prefix.

Fixes #11823 .
Hi I'm very new to rust-analyzer and not sure how the review process are. Can somebody take a look at this PR? thanks!

crates/ide-completion/src/completions.rs

@@ -639,6 +639,7 @@ fn enum_variants_with_paths(
             ImportPathConfig {
                 prefer_no_std: ctx.config.prefer_no_std,
                 prefer_prelude: ctx.config.prefer_prelude,
+                prefer_absolute: ctx.config.prefer_absolute,
             },
         ) {
             // Variants with trivial paths are already added by the existing completion logic,

crates/ide-completion/src/completions/expr.rs

@@ -177,6 +177,7 @@ pub(crate) fn complete_expr_path(
                                 ImportPathConfig {
                                     prefer_no_std: ctx.config.prefer_no_std,
                                     prefer_prelude: ctx.config.prefer_prelude,
+                                    prefer_absolute: ctx.config.prefer_absolute,
                                 },
                             )
                             .filter(|it| it.len() > 1);
@@ -202,6 +203,7 @@ pub(crate) fn complete_expr_path(
                                 ImportPathConfig {
                                     prefer_no_std: ctx.config.prefer_no_std,
                                     prefer_prelude: ctx.config.prefer_prelude,
+                                    prefer_absolute: ctx.config.prefer_absolute,
                                 },
                             )
                             .filter(|it| it.len() > 1);

crates/ide-completion/src/completions/flyimport.rs

@@ -259,6 +259,7 @@ fn import_on_the_fly(
     let import_cfg = ImportPathConfig {
         prefer_no_std: ctx.config.prefer_no_std,
         prefer_prelude: ctx.config.prefer_prelude,
+        prefer_absolute: ctx.config.prefer_absolute,
     };
 
     import_assets
@@ -309,6 +310,7 @@ fn import_on_the_fly_pat_(
     let cfg = ImportPathConfig {
         prefer_no_std: ctx.config.prefer_no_std,
         prefer_prelude: ctx.config.prefer_prelude,
+        prefer_absolute: ctx.config.prefer_absolute,
     };
 
     import_assets
@@ -354,6 +356,7 @@ fn import_on_the_fly_method(
     let cfg = ImportPathConfig {
         prefer_no_std: ctx.config.prefer_no_std,
         prefer_prelude: ctx.config.prefer_prelude,
+        prefer_absolute: ctx.config.prefer_absolute,
     };
 
     import_assets

crates/ide-completion/src/completions/postfix.rs

@@ -63,6 +63,7 @@ pub(crate) fn complete_postfix(
     let cfg = ImportPathConfig {
         prefer_no_std: ctx.config.prefer_no_std,
         prefer_prelude: ctx.config.prefer_prelude,
+        prefer_absolute: ctx.config.prefer_absolute,
     };
 
     if let Some(drop_trait) = ctx.famous_defs().core_ops_Drop() {

crates/ide-completion/src/config.rs

@@ -22,6 +22,7 @@ pub struct CompletionConfig {
     pub insert_use: InsertUseConfig,
     pub prefer_no_std: bool,
     pub prefer_prelude: bool,
+    pub prefer_absolute: bool,
     pub snippets: Vec<Snippet>,
     pub limit: Option<usize>,
 }

crates/ide-completion/src/lib.rs

@@ -253,6 +253,7 @@ pub fn resolve_completion_edits(
     let cfg = ImportPathConfig {
         prefer_no_std: config.prefer_no_std,
         prefer_prelude: config.prefer_prelude,
+        prefer_absolute: config.prefer_absolute,
     };
 
     imports.into_iter().for_each(|(full_import_path, imported_name)| {

crates/ide-completion/src/render.rs

@@ -298,6 +298,7 @@ pub(crate) fn render_expr(
     let cfg = ImportPathConfig {
         prefer_no_std: ctx.config.prefer_no_std,
         prefer_prelude: ctx.config.prefer_prelude,
+        prefer_absolute: ctx.config.prefer_absolute,
     };
 
     let label = expr.gen_source_code(&ctx.scope, &mut label_formatter, cfg).ok()?;

crates/ide-completion/src/snippet.rs

@@ -172,6 +172,7 @@ fn import_edits(ctx: &CompletionContext<'_>, requires: &[GreenNode]) -> Option<V
     let import_cfg = ImportPathConfig {
         prefer_no_std: ctx.config.prefer_no_std,
         prefer_prelude: ctx.config.prefer_prelude,
+        prefer_absolute: ctx.config.prefer_absolute,
     };
 
     let resolve = |import: &GreenNode| {

crates/ide-completion/src/tests.rs

@@ -79,6 +79,7 @@ pub(crate) const TEST_CONFIG: CompletionConfig = CompletionConfig {
     },
     prefer_no_std: false,
     prefer_prelude: true,
+    prefer_absolute: false,
     snippets: Vec::new(),
     limit: None,
 };

crates/ide-completion/src/tests/flyimport.rs

@@ -870,6 +870,38 @@ fn main() {
     );
 }
 
+#[test]
+fn config_prefer_absolute() {
+    let fixture = r#"
+//- /lib.rs crate:dep
+pub mod foo {
+    pub mod bar {
+        pub struct Item;
+    }
+}
+
+//- /main.rs crate:main deps:dep
+use ::dep::foo::bar;
+
+fn main() {
+    Ite$0
+}"#;
+    let mut config = TEST_CONFIG;
+    config.prefer_absolute = true;
+
+    check_edit_with_config(
+        config.clone(),
+        "Item",
+        fixture,
+        r#"
+use ::dep::foo::bar::{self, Item};
+
+fn main() {
+    Item
+}"#,
+    );
+}
+
 #[test]
 fn unresolved_qualifier() {
     let fixture = r#"