19 files changed, 158 insertions, 100 deletions

diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index 7663d211d..4964ddc7d 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -272,6 +272,34 @@ mod tests {
     }
 
     #[test]
+    fn partial_fill_option() {
+        check_assist(
+            fill_match_arms,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn main() {
+    match None$0 {
+        None => {}
+    }
+}
+            "#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn main() {
+    match None {
+        None => {}
+        Some(${0:_}) => {}
+    }
+}
+            "#,
+        );
+    }
+
+    #[test]
     fn partial_fill_or_pat() {
         check_assist(
             fill_match_arms,
diff --git a/crates/completion/src/item.rs b/crates/completion/src/item.rs
index eeb952ec3..8ec4ac65e 100644
--- a/crates/completion/src/item.rs
+++ b/crates/completion/src/item.rs
@@ -10,7 +10,7 @@ use ide_db::{
     },
     SymbolKind,
 };
-use stdx::{assert_never, impl_from};
+use stdx::{impl_from, never};
 use syntax::{algo, TextRange};
 use text_edit::TextEdit;
 
@@ -404,7 +404,7 @@ impl Builder {
     pub(crate) fn set_detail(mut self, detail: Option<impl Into<String>>) -> Builder {
         self.detail = detail.map(Into::into);
         if let Some(detail) = &self.detail {
-            if assert_never!(detail.contains('\n'), "multiline detail:\n{}", detail) {
+            if never!(detail.contains('\n'), "multiline detail:\n{}", detail) {
                 self.detail = Some(detail.splitn(2, '\n').next().unwrap().to_string());
             }
         }
diff --git a/crates/hir_def/src/body.rs b/crates/hir_def/src/body.rs
index d0c84ab0b..b9ecf22fa 100644
--- a/crates/hir_def/src/body.rs
+++ b/crates/hir_def/src/body.rs
@@ -17,6 +17,7 @@ use hir_expand::{
     HirFileId, InFile, MacroDefId,
 };
 use la_arena::{Arena, ArenaMap};
+use profile::Count;
 use rustc_hash::FxHashMap;
 use syntax::{ast, AstNode, AstPtr};
 use test_utils::mark;
@@ -237,6 +238,7 @@ pub struct Body {
     /// The `ExprId` of the actual body expression.
     pub body_expr: ExprId,
     pub item_scope: ItemScope,
+    _c: Count<Self>,
 }
 
 pub type ExprPtr = AstPtr<ast::Expr>;
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 4ce5e5b72..209965fca 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -10,6 +10,7 @@ use hir_expand::{
     ExpandError, HirFileId, MacroDefId, MacroDefKind,
 };
 use la_arena::Arena;
+use profile::Count;
 use rustc_hash::FxHashMap;
 use syntax::{
     ast::{
@@ -77,6 +78,7 @@ pub(super) fn lower(
             params: Vec::new(),
             body_expr: dummy_expr_id(),
             item_scope: Default::default(),
+            _c: Count::new(),
         },
         item_trees: {
             let mut map = FxHashMap::default();
diff --git a/crates/hir_expand/src/ast_id_map.rs b/crates/hir_expand/src/ast_id_map.rs
index 0991fffd8..16cf29907 100644
--- a/crates/hir_expand/src/ast_id_map.rs
+++ b/crates/hir_expand/src/ast_id_map.rs
@@ -13,6 +13,7 @@ use std::{
 };
 
 use la_arena::{Arena, Idx};
+use profile::Count;
 use syntax::{ast, match_ast, AstNode, AstPtr, SyntaxNode, SyntaxNodePtr};
 
 /// `AstId` points to an AST node in a specific file.
@@ -62,12 +63,13 @@ type ErasedFileAstId = Idx<SyntaxNodePtr>;
 #[derive(Debug, PartialEq, Eq, Default)]
 pub struct AstIdMap {
     arena: Arena<SyntaxNodePtr>,
+    _c: Count<Self>,
 }
 
 impl AstIdMap {
     pub(crate) fn from_source(node: &SyntaxNode) -> AstIdMap {
         assert!(node.parent().is_none());
-        let mut res = AstIdMap { arena: Arena::default() };
+        let mut res = AstIdMap::default();
         // By walking the tree in breadth-first order we make sure that parents
         // get lower ids then children. That is, adding a new child does not
         // change parent's id. This means that, say, adding a new function to a
diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index db42a00dc..c7502bf57 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -17,9 +17,9 @@ ena = "0.14.0"
 log = "0.4.8"
 rustc-hash = "1.1.0"
 scoped-tls = "1"
-chalk-solve = { version = "0.50", default-features = false }
-chalk-ir = "0.50"
-chalk-recursive = "0.50"
+chalk-solve = { version = "0.51", default-features = false }
+chalk-ir = "0.51"
+chalk-recursive = "0.51"
 la-arena = { version = "0.2.0", path = "../../lib/arena" }
 
 stdx = { path = "../stdx", version = "0.0.0" }
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 54485fd30..2f37c8040 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -416,8 +416,11 @@ fn get_string_representation(expr: &ast::Expr) -> Option<String> {
                 name_ref => Some(name_ref.to_owned()),
             }
         }
+        ast::Expr::FieldExpr(field_expr) => Some(field_expr.name_ref()?.to_string()),
+        ast::Expr::PathExpr(path_expr) => Some(path_expr.to_string()),
+        ast::Expr::PrefixExpr(prefix_expr) => get_string_representation(&prefix_expr.expr()?),
         ast::Expr::RefExpr(ref_expr) => get_string_representation(&ref_expr.expr()?),
-        _ => Some(expr.to_string()),
+        _ => None,
     }
 }
 
@@ -1438,4 +1441,19 @@ fn main() {
 "#,
         )
     }
+
+    #[test]
+    fn param_name_hints_show_for_literals() {
+        check(
+            r#"pub fn test(a: i32, b: i32) -> [i32; 2] { [a, b] }
+fn main() {
+    test(
+        0x0fab272b,
+      //^^^^^^^^^^ a
+        0x0fab272b
+      //^^^^^^^^^^ b
+    );
+}"#,
+        )
+    }
 }
diff --git a/crates/ide/src/references/rename.rs b/crates/ide/src/references/rename.rs
index c25bcce50..99a558532 100644
--- a/crates/ide/src/references/rename.rs
+++ b/crates/ide/src/references/rename.rs
@@ -9,7 +9,7 @@ use ide_db::{
     search::FileReference,
     RootDatabase,
 };
-use stdx::assert_never;
+use stdx::never;
 use syntax::{
     ast::{self, NameOwner},
     lex_single_syntax_kind, AstNode, SyntaxKind, SyntaxNode, T,
@@ -285,7 +285,7 @@ fn rename_mod(
 }
 
 fn rename_to_self(sema: &Semantics<RootDatabase>, local: hir::Local) -> RenameResult<SourceChange> {
-    if assert_never!(local.is_self(sema.db)) {
+    if never!(local.is_self(sema.db)) {
         bail!("rename_to_self invoked on self");
     }
 
@@ -388,7 +388,7 @@ fn rename_self_to_param(
     let (file_id, self_param) = match local.source(sema.db) {
         InFile { file_id, value: Either::Right(self_param) } => (file_id, self_param),
         _ => {
-            assert_never!(true, "rename_self_to_param invoked on a non-self local");
+            never!(true, "rename_self_to_param invoked on a non-self local");
             bail!("rename_self_to_param invoked on a non-self local");
         }
     };
diff --git a/crates/ide_db/src/source_change.rs b/crates/ide_db/src/source_change.rs
index b1f87731b..f76bac151 100644
--- a/crates/ide_db/src/source_change.rs
+++ b/crates/ide_db/src/source_change.rs
@@ -10,7 +10,7 @@ use std::{
 
 use base_db::{AnchoredPathBuf, FileId};
 use rustc_hash::FxHashMap;
-use stdx::assert_never;
+use stdx::never;
 use text_edit::TextEdit;
 
 #[derive(Default, Debug, Clone)]
@@ -40,10 +40,7 @@ impl SourceChange {
     pub fn insert_source_edit(&mut self, file_id: FileId, edit: TextEdit) {
         match self.source_file_edits.entry(file_id) {
             Entry::Occupied(mut entry) => {
-                assert_never!(
-                    entry.get_mut().union(edit).is_err(),
-                    "overlapping edits for same file"
-                );
+                never!(entry.get_mut().union(edit).is_err(), "overlapping edits for same file");
             }
             Entry::Vacant(entry) => {
                 entry.insert(edit);
diff --git a/crates/profile/Cargo.toml b/crates/profile/Cargo.toml
index 4dd9acc98..486f9c164 100644
--- a/crates/profile/Cargo.toml
+++ b/crates/profile/Cargo.toml
@@ -14,7 +14,7 @@ once_cell = "1.3.1"
 cfg-if = "1"
 libc = "0.2.73"
 la-arena = { version = "0.2.0", path = "../../lib/arena" }
-countme = { version = "2.0.0", features = ["enable"] }
+countme = { version = "2.0.1", features = ["enable"] }
 jemalloc-ctl = { version = "0.3.3", optional = true }
 
 [target.'cfg(target_os = "linux")'.dependencies]
diff --git a/crates/project_model/src/build_data.rs b/crates/project_model/src/build_data.rs
index cf32995e0..3ff347e2c 100644
--- a/crates/project_model/src/build_data.rs
+++ b/crates/project_model/src/build_data.rs
@@ -175,7 +175,7 @@ fn is_dylib(path: &Path) -> bool {
 /// Should be synced with <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates>
 fn inject_cargo_env(package: &cargo_metadata::Package, env: &mut Vec<(String, String)>) {
     // FIXME: Missing variables:
-    // CARGO, CARGO_PKG_HOMEPAGE, CARGO_CRATE_NAME, CARGO_BIN_NAME, CARGO_BIN_EXE_<name>
+    // CARGO_PKG_HOMEPAGE, CARGO_CRATE_NAME, CARGO_BIN_NAME, CARGO_BIN_EXE_<name>
 
     let mut manifest_dir = package.manifest_path.clone();
     manifest_dir.pop();
@@ -183,6 +183,9 @@ fn inject_cargo_env(package: &cargo_metadata::Package, env: &mut Vec<(String, St
         env.push(("CARGO_MANIFEST_DIR".into(), cargo_manifest_dir.into()));
     }
 
+    // Not always right, but works for common cases.
+    env.push(("CARGO".into(), "cargo".into()));
+
     env.push(("CARGO_PKG_VERSION".into(), package.version.to_string()));
     env.push(("CARGO_PKG_VERSION_MAJOR".into(), package.version.major.to_string()));
     env.push(("CARGO_PKG_VERSION_MINOR".into(), package.version.minor.to_string()));
diff --git a/crates/rust-analyzer/Cargo.toml b/crates/rust-analyzer/Cargo.toml
index 268c00942..82ea76666 100644
--- a/crates/rust-analyzer/Cargo.toml
+++ b/crates/rust-analyzer/Cargo.toml
@@ -37,6 +37,7 @@ lsp-server = "0.5.0"
 tracing = "0.1"
 tracing-subscriber = { version = "0.2", default-features = false, features = ["env-filter", "registry"] }
 tracing-tree = { version = "0.1.4" }
+always-assert = "0.1"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 flycheck = { path = "../flycheck", version = "0.0.0" }
@@ -72,3 +73,4 @@ tt = { path = "../tt" }
 
 [features]
 jemalloc = ["jemallocator", "profile/jemalloc"]
+force-always-assert = ["always-assert/force"]
diff --git a/crates/rust-analyzer/src/bin/args.rs b/crates/rust-analyzer/src/bin/args.rs
index 7d917946e..2a532361d 100644
--- a/crates/rust-analyzer/src/bin/args.rs
+++ b/crates/rust-analyzer/src/bin/args.rs
@@ -14,7 +14,10 @@ use vfs::AbsPathBuf;
 pub(crate) struct Args {
     pub(crate) verbosity: Verbosity,
     pub(crate) log_file: Option<PathBuf>,
+    pub(crate) no_buffering: bool,
     pub(crate) command: Command,
+    #[allow(unused)]
+    pub(crate) wait_dbg: bool,
 }
 
 pub(crate) enum Command {
@@ -47,11 +50,17 @@ FLAGS:
     -vv, --spammy
     -q,  --quiet      Set verbosity
 
-    --log-file <PATH> Log to the specified filed instead of stderr
+    --log-file <PATH> Log to the specified file instead of stderr
+    --no-log-buffering
+                      Flush log records to the file immediately
+
+    --wait-dbg        Wait until a debugger is attached to.
+                      The flag is valid for debug builds only
 
 ENVIRONMENTAL VARIABLES:
     RA_LOG            Set log filter in env_logger format
     RA_PROFILE        Enable hierarchical profiler
+    RA_WAIT_DBG       If set acts like a --wait-dbg flag
 
 COMMANDS:
 
@@ -114,6 +123,8 @@ impl Args {
                 verbosity: Verbosity::Normal,
                 log_file: None,
                 command: Command::Version,
+                no_buffering: false,
+                wait_dbg: false,
             });
         }
 
@@ -130,21 +141,41 @@ impl Args {
             (false, true, true) => bail!("Invalid flags: -q conflicts with -v"),
         };
         let log_file = matches.opt_value_from_str("--log-file")?;
+        let no_buffering = matches.contains("--no-log-buffering");
+        let wait_dbg = matches.contains("--wait-dbg");
 
         if matches.contains(["-h", "--help"]) {
             eprintln!("{}", HELP);
-            return Ok(Args { verbosity, log_file: None, command: Command::Help });
+            return Ok(Args {
+                verbosity,
+                log_file: None,
+                command: Command::Help,
+                no_buffering,
+                wait_dbg,
+            });
         }
 
         if matches.contains("--print-config-schema") {
-            return Ok(Args { verbosity, log_file, command: Command::PrintConfigSchema });
+            return Ok(Args {
+                verbosity,
+                log_file,
+                command: Command::PrintConfigSchema,
+                no_buffering,
+                wait_dbg,
+            });
         }
 
         let subcommand = match matches.subcommand()? {
             Some(it) => it,
             None => {
                 finish_args(matches)?;
-                return Ok(Args { verbosity, log_file, command: Command::RunServer });
+                return Ok(Args {
+                    verbosity,
+                    log_file,
+                    command: Command::RunServer,
+                    no_buffering,
+                    wait_dbg,
+                });
             }
         };
         let command = match subcommand.as_str() {
@@ -219,11 +250,17 @@ impl Args {
             },
             _ => {
                 eprintln!("{}", HELP);
-                return Ok(Args { verbosity, log_file: None, command: Command::Help });
+                return Ok(Args {
+                    verbosity,
+                    log_file: None,
+                    command: Command::Help,
+                    no_buffering,
+                    wait_dbg,
+                });
             }
         };
         finish_args(matches)?;
-        Ok(Args { verbosity, log_file, command })
+        Ok(Args { verbosity, log_file, command, no_buffering, wait_dbg })
     }
 }
 
diff --git a/crates/rust-analyzer/src/bin/logger.rs b/crates/rust-analyzer/src/bin/logger.rs
index 3bcb1ae37..14887c5cc 100644
--- a/crates/rust-analyzer/src/bin/logger.rs
+++ b/crates/rust-analyzer/src/bin/logger.rs
@@ -4,7 +4,7 @@
 
 use std::{
     fs::File,
-    io::{BufWriter, Write},
+    io::{self, BufWriter, Write},
 };
 
 use env_logger::filter::{Builder, Filter};
@@ -14,10 +14,11 @@ use parking_lot::Mutex;
 pub(crate) struct Logger {
     filter: Filter,
     file: Option<Mutex<BufWriter<File>>>,
+    no_buffering: bool,
 }
 
 impl Logger {
-    pub(crate) fn new(log_file: Option<File>, filter: Option<&str>) -> Logger {
+    pub(crate) fn new(log_file: Option<File>, no_buffering: bool, filter: Option<&str>) -> Logger {
         let filter = {
             let mut builder = Builder::new();
             if let Some(filter) = filter {
@@ -28,7 +29,7 @@ impl Logger {
 
         let file = log_file.map(|it| Mutex::new(BufWriter::new(it)));
 
-        Logger { filter, file }
+        Logger { filter, file, no_buffering }
     }
 
     pub(crate) fn install(self) {
@@ -46,7 +47,8 @@ impl Log for Logger {
         if !self.filter.matches(record) {
             return;
         }
-        match &self.file {
+
+        let should_flush = match &self.file {
             Some(w) => {
                 let _ = writeln!(
                     w.lock(),
@@ -55,19 +57,32 @@ impl Log for Logger {
                     record.module_path().unwrap_or_default(),
                     record.args(),
                 );
+                self.no_buffering
+            }
+            None => {
+                eprintln!(
+                    "[{} {}] {}",
+                    record.level(),
+                    record.module_path().unwrap_or_default(),
+                    record.args(),
+                );
+                true // flush stderr unconditionally
             }
-            None => eprintln!(
-                "[{} {}] {}",
-                record.level(),
-                record.module_path().unwrap_or_default(),
-                record.args(),
-            ),
+        };
+
+        if should_flush {
+            self.flush();
         }
     }
 
     fn flush(&self) {
-        if let Some(w) = &self.file {
-            let _ = w.lock().flush();
+        match &self.file {
+            Some(w) => {
+                let _ = w.lock().flush();
+            }
+            None => {
+                let _ = io::stderr().flush();
+            }
         }
     }
 }
diff --git a/crates/rust-analyzer/src/bin/main.rs b/crates/rust-analyzer/src/bin/main.rs
index 1d6e5478b..088b17b03 100644
--- a/crates/rust-analyzer/src/bin/main.rs
+++ b/crates/rust-analyzer/src/bin/main.rs
@@ -21,6 +21,7 @@ static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
 
 fn main() {
     if let Err(err) = try_main() {
+        log::error!("Unexpected error: {}", err);
         eprintln!("{}", err);
         process::exit(101);
     }
@@ -28,7 +29,17 @@ fn main() {
 
 fn try_main() -> Result<()> {
     let args = args::Args::parse()?;
-    setup_logging(args.log_file)?;
+
+    #[cfg(debug_assertions)]
+    if args.wait_dbg || env::var("RA_WAIT_DBG").is_ok() {
+        #[allow(unused_mut)]
+        let mut d = 4;
+        while d == 4 {
+            d = 4;
+        }
+    }
+
+    setup_logging(args.log_file, args.no_buffering)?;
     match args.command {
         args::Command::RunServer => run_server()?,
         args::Command::PrintConfigSchema => {
@@ -56,7 +67,7 @@ fn try_main() -> Result<()> {
     Ok(())
 }
 
-fn setup_logging(log_file: Option<PathBuf>) -> Result<()> {
+fn setup_logging(log_file: Option<PathBuf>, no_buffering: bool) -> Result<()> {
     env::set_var("RUST_BACKTRACE", "short");
 
     let log_file = match log_file {
@@ -69,21 +80,12 @@ fn setup_logging(log_file: Option<PathBuf>) -> Result<()> {
         None => None,
     };
     let filter = env::var("RA_LOG").ok();
-    logger::Logger::new(log_file, filter.as_deref()).install();
+    logger::Logger::new(log_file, no_buffering, filter.as_deref()).install();
 
     tracing_setup::setup_tracing()?;
 
     profile::init();
 
-    if !cfg!(debug_assertions) {
-        stdx::set_assert_hook(|loc, args| {
-            if env::var("RA_PROFILE").is_ok() {
-                panic!("assertion failed at {}: {}", loc, args)
-            }
-            log::error!("assertion failed at {}: {}", loc, args)
-        });
-    }
-
     Ok(())
 }
 
diff --git a/crates/stdx/Cargo.toml b/crates/stdx/Cargo.toml
index c47e8d0a8..5866c0a28 100644
--- a/crates/stdx/Cargo.toml
+++ b/crates/stdx/Cargo.toml
@@ -11,6 +11,7 @@ doctest = false
 
 [dependencies]
 backtrace = { version = "0.3.44", optional = true }
+always-assert = { version = "0.1.1", features = ["log"] }
 # Think twice before adding anything here
 
 [features]
diff --git a/crates/stdx/src/lib.rs b/crates/stdx/src/lib.rs
index d42817078..d26be4853 100644
--- a/crates/stdx/src/lib.rs
+++ b/crates/stdx/src/lib.rs
@@ -4,7 +4,7 @@ use std::{cmp::Ordering, ops, process, time::Instant};
 mod macros;
 pub mod panic_context;
 
-pub use crate::macros::{on_assert_failure, set_assert_hook};
+pub use always_assert::{always, never};
 
 #[inline(always)]
 pub fn is_ci() -> bool {
diff --git a/crates/stdx/src/macros.rs b/crates/stdx/src/macros.rs
index 4f5c6100d..d91fc690c 100644
--- a/crates/stdx/src/macros.rs
+++ b/crates/stdx/src/macros.rs
@@ -1,9 +1,5 @@
 //! Convenience macros.
 
-use std::{
-    fmt, mem, panic,
-    sync::atomic::{AtomicUsize, Ordering::SeqCst},
-};
 #[macro_export]
 macro_rules! eprintln {
     ($($tt:tt)*) => {{
@@ -49,50 +45,3 @@ macro_rules! impl_from {
         )*
     }
 }
-
-/// A version of `assert!` macro which allows to handle an assertion failure.
-///
-/// In release mode, it returns the condition and logs an error.
-///
-/// ```
-/// if assert_never!(impossible) {
-///     // Heh, this shouldn't have happened, but lets try to soldier on...
-///     return None;
-/// }
-/// ```
-///
-/// Rust analyzer is a long-running process, and crashing really isn't an option.
-///
-/// Shamelessly stolen from: https://www.sqlite.org/assert.html
-#[macro_export]
-macro_rules! assert_never {
-    ($cond:expr) => { $crate::assert_never!($cond, "") };
-    ($cond:expr, $($fmt:tt)*) => {{
-        let value = $cond;
-        if value {
-            $crate::on_assert_failure(
-                format_args!($($fmt)*)
-            );
-        }
-        value
-    }};
-}
-
-type AssertHook = fn(&panic::Location<'_>, fmt::Arguments<'_>);
-static HOOK: AtomicUsize = AtomicUsize::new(0);
-
-pub fn set_assert_hook(hook: AssertHook) {
-    HOOK.store(hook as usize, SeqCst);
-}
-
-#[cold]
-#[track_caller]
-pub fn on_assert_failure(args: fmt::Arguments) {
-    let hook: usize = HOOK.load(SeqCst);
-    if hook == 0 {
-        panic!("\n  assertion failed: {}\n", args);
-    }
-
-    let hook: AssertHook = unsafe { mem::transmute::<usize, AssertHook>(hook) };
-    hook(panic::Location::caller(), args)
-}
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index e70fbba9c..de65585cb 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 [dependencies]
 itertools = "0.10.0"
 rowan = "0.12.2"
-rustc_lexer = { version = "700.0.0", package = "rustc-ap-rustc_lexer" }
+rustc_lexer = { version = "701.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 arrayvec = "0.5.1"
 once_cell = "1.3.1"