Merge #4913 #4915 #4916

4913: Remove debugging code for incremental sync r=matklad a=lnicola



4915: Inspect markdown code fences to determine whether to apply syntax highlighting r=matklad a=ltentrup

Fixes #4904 

4916: Warnings as hint or info r=matklad a=GabbeV

Fixes #4229 

This PR is my second attempt at providing a solution to the above issue. My last PR(#4721) had to be rolled back(#4862) due to it overriding behavior many users expected. This PR solves a broader problem while trying to minimize surprises for the users. 

### Problem description
The underlying problem this PR tries to solve is the mismatch between [Rustc lint levels](https://doc.rust-lang.org/rustc/lints/levels.html) and [LSP diagnostic severity](https://microsoft.github.io/language-server-protocol/specification#diagnostic). Rustc currently doesn't have a lint level less severe than warning forcing the user to disable warnings if they think they get to noisy. LSP however provides two severitys below warning, information and hint. This allows editors like VSCode to provide more fine grained control over how prominently to show different diagnostics.

Info severity shows a blue squiggly underline in code and can be filtered separately from errors and warnings in the problems panel.
![image](https://user-images.githubusercontent.com/13839236/84830640-0bb8d900-b02a-11ea-9e2f-0561b0e8f1ef.png)
![image](https://user-images.githubusercontent.com/13839236/84826931-ffca1880-b023-11ea-8080-5e5b91a6ac0d.png)

Hint severity doesn't show up in the problems panel at all and only show three dots under the affected code or just faded text if the diagnostic also has the unnecessary tag.
![image](https://user-images.githubusercontent.com/13839236/84827165-55062a00-b024-11ea-8bd6-bdbf1217c4c5.png)

### Solution
The solution provided by this PR allows the user to configure lists of of warnings to report as info severity and hint severity respectively. I purposefully only convert warnings and not errors as i believe it's a good idea to have the editor show the same severity as the compiler as much as possible.
![image](https://user-images.githubusercontent.com/13839236/84829609-50437500-b028-11ea-80a8-1bbd05680ba7.png)

### Open questions
#### Discoverability
How do we teach this to new and existing users? Should a section be added to the user manual? If so  where and what should it say?

#### Defaults
Other languages such as TypeScript report unused code as hint by default. Should rust-analyzer similarly report some problems as hint/info by default?

Co-authored-by: Laurențiu Nicola <[email protected]>
Co-authored-by: Leander Tentrup <[email protected]>
Co-authored-by: Gabriel Valfridsson <[email protected]>

Author: 4 people

crates/ra_ide/src/snapshots/highlight_doctest.html

@@ -73,9 +73,13 @@
     <span class="comment">///</span>
     <span class="comment">/// ```</span>
     <span class="comment">///</span>
-    <span class="comment">/// ```</span>
+    <span class="comment">/// ```rust,no_run</span>
     <span class="comment">/// </span><span class="keyword">let</span> <span class="variable declaration">foobar</span> = <span class="struct">Foo</span>::<span class="function">new</span>().<span class="function">bar</span>();
     <span class="comment">/// ```</span>
+    <span class="comment">///</span>
+    <span class="comment">/// ```sh</span>
+    <span class="comment">/// echo 1</span>
+    <span class="comment">/// ```</span>
     <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration">foo</span>(&<span class="self_keyword">self</span>) -&gt; <span class="builtin_type">bool</span> {
         <span class="bool_literal">true</span>
     }

crates/ra_ide/src/syntax_highlighting/injection.rs

@@ -53,6 +53,10 @@ pub(super) fn highlight_injection(
 /// Mapping from extracted documentation code to original code
 type RangesMap = BTreeMap<TextSize, TextSize>;
 
+const RUSTDOC_FENCE: &'static str = "```";
+const RUSTDOC_FENCE_TOKENS: &[&'static str] =
+    &["", "rust", "should_panic", "ignore", "no_run", "compile_fail", "edition2015", "edition2018"];
+
 /// Extracts Rust code from documentation comments as well as a mapping from
 /// the extracted source code back to the original source ranges.
 /// Lastly, a vector of new comment highlight ranges (spanning only the
@@ -67,6 +71,7 @@ pub(super) fn extract_doc_comments(
     // Mapping from extracted documentation code to original code
     let mut range_mapping: RangesMap = BTreeMap::new();
     let mut line_start = TextSize::try_from(prefix.len()).unwrap();
+    let mut is_codeblock = false;
     let mut is_doctest = false;
     // Replace the original, line-spanning comment ranges by new, only comment-prefix
     // spanning comment ranges.
@@ -76,8 +81,13 @@ pub(super) fn extract_doc_comments(
         .filter_map(|el| el.into_token().and_then(ast::Comment::cast))
         .filter(|comment| comment.kind().doc.is_some())
         .filter(|comment| {
-            if comment.text().contains("```") {
-                is_doctest = !is_doctest;
+            if let Some(idx) = comment.text().find(RUSTDOC_FENCE) {
+                is_codeblock = !is_codeblock;
+                // Check whether code is rust by inspecting fence guards
+                let guards = &comment.text()[idx + RUSTDOC_FENCE.len()..];
+                let is_rust =
+                    guards.split(',').all(|sub| RUSTDOC_FENCE_TOKENS.contains(&sub.trim()));
+                is_doctest = is_codeblock && is_rust;
                 false
             } else {
                 is_doctest

crates/ra_ide/src/syntax_highlighting/tests.rs

@@ -329,9 +329,13 @@ impl Foo {
     ///
     /// ```
     ///
-    /// ```
+    /// ```rust,no_run
     /// let foobar = Foo::new().bar();
     /// ```
+    ///
+    /// ```sh
+    /// echo 1
+    /// ```
     pub fn foo(&self) -> bool {
         true
     }

crates/rust-analyzer/src/config.rs

@@ -9,6 +9,7 @@
 
 use std::{ffi::OsString, path::PathBuf};
 
+use crate::diagnostics::DiagnosticsConfig;
 use lsp_types::ClientCapabilities;
 use ra_flycheck::FlycheckConfig;
 use ra_ide::{AssistConfig, CompletionConfig, HoverConfig, InlayHintsConfig};
@@ -20,6 +21,7 @@ pub struct Config {
     pub client_caps: ClientCapsConfig,
 
     pub publish_diagnostics: bool,
+    pub diagnostics: DiagnosticsConfig,
     pub lru_capacity: Option<usize>,
     pub proc_macro_srv: Option<(PathBuf, Vec<OsString>)>,
     pub files: FilesConfig,
@@ -136,6 +138,7 @@ impl Default for Config {
 
             with_sysroot: true,
             publish_diagnostics: true,
+            diagnostics: DiagnosticsConfig::default(),
             lru_capacity: None,
             proc_macro_srv: None,
             files: FilesConfig { watcher: FilesWatcher::Notify, exclude: Vec::new() },
@@ -184,6 +187,8 @@ impl Config {
 
         set(value, "/withSysroot", &mut self.with_sysroot);
         set(value, "/diagnostics/enable", &mut self.publish_diagnostics);
+        set(value, "/diagnostics/warningsAsInfo", &mut self.diagnostics.warnings_as_info);
+        set(value, "/diagnostics/warningsAsHint", &mut self.diagnostics.warnings_as_hint);
         set(value, "/lruCapacity", &mut self.lru_capacity);
         self.files.watcher = match get(value, "/files/watcher") {
             Some("client") => FilesWatcher::Client,

crates/rust-analyzer/src/diagnostics.rs

@@ -10,6 +10,12 @@ use crate::lsp_ext;
 
 pub type CheckFixes = Arc<HashMap<FileId, Vec<Fix>>>;
 
+#[derive(Debug, Default, Clone)]
+pub struct DiagnosticsConfig {
+    pub warnings_as_info: Vec<String>,
+    pub warnings_as_hint: Vec<String>,
+}
+
 #[derive(Debug, Default, Clone)]
 pub struct DiagnosticCollection {
     pub native: HashMap<FileId, Vec<Diagnostic>>,

crates/rust-analyzer/src/diagnostics/snapshots/rust_analyzer__diagnostics__to_proto__tests__snap_rustc_unused_variable_as_hint.snap

@@ -0,0 +1,86 @@
+---
+source: crates/rust-analyzer/src/diagnostics/to_proto.rs
+expression: diag
+---
+[
+    MappedRustDiagnostic {
+        location: Location {
+            uri: "file:///test/driver/subcommand/repl.rs",
+            range: Range {
+                start: Position {
+                    line: 290,
+                    character: 8,
+                },
+                end: Position {
+                    line: 290,
+                    character: 11,
+                },
+            },
+        },
+        diagnostic: Diagnostic {
+            range: Range {
+                start: Position {
+                    line: 290,
+                    character: 8,
+                },
+                end: Position {
+                    line: 290,
+                    character: 11,
+                },
+            },
+            severity: Some(
+                Hint,
+            ),
+            code: Some(
+                String(
+                    "unused_variables",
+                ),
+            ),
+            source: Some(
+                "rustc",
+            ),
+            message: "unused variable: `foo`\n#[warn(unused_variables)] on by default",
+            related_information: None,
+            tags: Some(
+                [
+                    Unnecessary,
+                ],
+            ),
+        },
+        fixes: [
+            CodeAction {
+                title: "consider prefixing with an underscore",
+                id: None,
+                group: None,
+                kind: Some(
+                    "quickfix",
+                ),
+                command: None,
+                edit: Some(
+                    SnippetWorkspaceEdit {
+                        changes: Some(
+                            {
+                                "file:///test/driver/subcommand/repl.rs": [
+                                    TextEdit {
+                                        range: Range {
+                                            start: Position {
+                                                line: 290,
+                                                character: 8,
+                                            },
+                                            end: Position {
+                                                line: 290,
+                                                character: 11,
+                                            },
+                                        },
+                                        new_text: "_foo",
+                                    },
+                                ],
+                            },
+                        ),
+                        document_changes: None,
+                    },
+                ),
+            },
+        ],
+    },
+]

crates/rust-analyzer/src/diagnostics/snapshots/rust_analyzer__diagnostics__to_proto__tests__snap_rustc_unused_variable_as_info.snap

@@ -0,0 +1,86 @@
+---
+source: crates/rust-analyzer/src/diagnostics/to_proto.rs
+expression: diag
+---
+[
+    MappedRustDiagnostic {
+        location: Location {
+            uri: "file:///test/driver/subcommand/repl.rs",
+            range: Range {
+                start: Position {
+                    line: 290,
+                    character: 8,
+                },
+                end: Position {
+                    line: 290,
+                    character: 11,
+                },
+            },
+        },
+        diagnostic: Diagnostic {
+            range: Range {
+                start: Position {
+                    line: 290,
+                    character: 8,
+                },
+                end: Position {
+                    line: 290,
+                    character: 11,
+                },
+            },
+            severity: Some(
+                Information,
+            ),
+            code: Some(
+                String(
+                    "unused_variables",
+                ),
+            ),
+            source: Some(
+                "rustc",
+            ),
+            message: "unused variable: `foo`\n#[warn(unused_variables)] on by default",
+            related_information: None,
+            tags: Some(
+                [
+                    Unnecessary,
+                ],
+            ),
+        },
+        fixes: [
+            CodeAction {
+                title: "consider prefixing with an underscore",
+                id: None,
+                group: None,
+                kind: Some(
+                    "quickfix",
+                ),
+                command: None,
+                edit: Some(
+                    SnippetWorkspaceEdit {
+                        changes: Some(
+                            {
+                                "file:///test/driver/subcommand/repl.rs": [
+                                    TextEdit {
+                                        range: Range {
+                                            start: Position {
+                                                line: 290,
+                                                character: 8,
+                                            },
+                                            end: Position {
+                                                line: 290,
+                                                character: 11,
+                                            },
+                                        },
+                                        new_text: "_foo",
+                                    },
+                                ],
+                            },
+                        ),
+                        document_changes: None,
+                    },
+                ),
+            },
+        ],
+    },
+]