6 files changed, 255 insertions, 137 deletions

diff --git a/crates/hir_ty/src/diagnostics.rs b/crates/hir_ty/src/diagnostics.rs
index dfe98571e..b58fe0ed7 100644
--- a/crates/hir_ty/src/diagnostics.rs
+++ b/crates/hir_ty/src/diagnostics.rs
@@ -36,6 +36,9 @@ pub fn validate_body(db: &dyn HirDatabase, owner: DefWithBodyId, sink: &mut Diag
     validator.validate_body(db);
 }
 
+// Diagnostic: no-such-field
+//
+// This diagnostic is triggered if created structure does not have field provided in record.
 #[derive(Debug)]
 pub struct NoSuchField {
     pub file: HirFileId,
@@ -60,6 +63,17 @@ impl Diagnostic for NoSuchField {
     }
 }
 
+// Diagnostic: missing-structure-fields
+//
+// This diagnostic is triggered if record lacks some fields that exist in the corresponding structure.
+//
+// Example:
+//
+// ```rust
+// struct A { a: u8, b: u8 }
+//
+// let a = A { a: 10 };
+// ```
 #[derive(Debug)]
 pub struct MissingFields {
     pub file: HirFileId,
@@ -96,6 +110,21 @@ impl Diagnostic for MissingFields {
     }
 }
 
+// Diagnostic: missing-pat-fields
+//
+// This diagnostic is triggered if pattern lacks some fields that exist in the corresponding structure.
+//
+// Example:
+//
+// ```rust
+// struct A { a: u8, b: u8 }
+//
+// let a = A { a: 10, b: 20 };
+//
+// if let A { a } = a {
+//     // ...
+// }
+// ```
 #[derive(Debug)]
 pub struct MissingPatFields {
     pub file: HirFileId,
@@ -130,6 +159,9 @@ impl Diagnostic for MissingPatFields {
     }
 }
 
+// Diagnostic: missing-match-arm
+//
+// This diagnostic is triggered if `match` block is missing one or more match arms.
 #[derive(Debug)]
 pub struct MissingMatchArms {
     pub file: HirFileId,
@@ -152,6 +184,17 @@ impl Diagnostic for MissingMatchArms {
     }
 }
 
+// Diagnostic: missing-ok-in-tail-expr
+//
+// This diagnostic is triggered if block that should return `Result` returns a value not wrapped in `Ok`.
+//
+// Example:
+//
+// ```rust
+// fn foo() -> Result<u8, ()> {
+//     10
+// }
+// ```
 #[derive(Debug)]
 pub struct MissingOkInTailExpr {
     pub file: HirFileId,
@@ -173,6 +216,9 @@ impl Diagnostic for MissingOkInTailExpr {
     }
 }
 
+// Diagnostic: break-outside-of-loop
+//
+// This diagnostic is triggered if `break` keyword is used outside of a loop.
 #[derive(Debug)]
 pub struct BreakOutsideOfLoop {
     pub file: HirFileId,
@@ -194,6 +240,9 @@ impl Diagnostic for BreakOutsideOfLoop {
     }
 }
 
+// Diagnostic: missing-unsafe
+//
+// This diagnostic is triggered if operation marked as `unsafe` is used outside of `unsafe` function or block.
 #[derive(Debug)]
 pub struct MissingUnsafe {
     pub file: HirFileId,
@@ -215,6 +264,9 @@ impl Diagnostic for MissingUnsafe {
     }
 }
 
+// Diagnostic: mismatched-arg-count
+//
+// This diagnostic is triggered if function is invoked with an incorrect amount of arguments.
 #[derive(Debug)]
 pub struct MismatchedArgCount {
     pub file: HirFileId,
@@ -264,6 +316,9 @@ impl fmt::Display for CaseType {
     }
 }
 
+// Diagnostic: incorrect-ident-case
+//
+// This diagnostic is triggered if item name doesn't follow https://doc.rust-lang.org/1.0.0/style/style/naming/README.html[Rust naming convention].
 #[derive(Debug)]
 pub struct IncorrectCase {
     pub file: HirFileId,
diff --git a/crates/hir_ty/src/diagnostics/decl_check.rs b/crates/hir_ty/src/diagnostics/decl_check.rs
index f987636fe..f179c62b7 100644
--- a/crates/hir_ty/src/diagnostics/decl_check.rs
+++ b/crates/hir_ty/src/diagnostics/decl_check.rs
@@ -708,11 +708,23 @@ fn foo() {
     }
 
     #[test]
-    fn incorrect_struct_name() {
+    fn incorrect_struct_names() {
         check_diagnostics(
             r#"
 struct non_camel_case_name {}
     // ^^^^^^^^^^^^^^^^^^^ Structure `non_camel_case_name` should have CamelCase name, e.g. `NonCamelCaseName`
+
+struct SCREAMING_CASE {}
+    // ^^^^^^^^^^^^^^ Structure `SCREAMING_CASE` should have CamelCase name, e.g. `ScreamingCase`
+"#,
+        );
+    }
+
+    #[test]
+    fn no_diagnostic_for_camel_cased_acronyms_in_struct_name() {
+        check_diagnostics(
+            r#"
+struct AABB {}
 "#,
         );
     }
@@ -728,11 +740,23 @@ struct SomeStruct { SomeField: u8 }
     }
 
     #[test]
-    fn incorrect_enum_name() {
+    fn incorrect_enum_names() {
         check_diagnostics(
             r#"
 enum some_enum { Val(u8) }
   // ^^^^^^^^^ Enum `some_enum` should have CamelCase name, e.g. `SomeEnum`
+
+enum SOME_ENUM
+  // ^^^^^^^^^ Enum `SOME_ENUM` should have CamelCase name, e.g. `SomeEnum`
+"#,
+        );
+    }
+
+    #[test]
+    fn no_diagnostic_for_camel_cased_acronyms_in_enum_name() {
+        check_diagnostics(
+            r#"
+enum AABB {}
 "#,
         );
     }
diff --git a/crates/hir_ty/src/diagnostics/decl_check/case_conv.rs b/crates/hir_ty/src/diagnostics/decl_check/case_conv.rs
index 3800f2a6b..b0144a289 100644
--- a/crates/hir_ty/src/diagnostics/decl_check/case_conv.rs
+++ b/crates/hir_ty/src/diagnostics/decl_check/case_conv.rs
@@ -1,150 +1,145 @@
 //! Functions for string case manipulation, such as detecting the identifier case,
 //! and converting it into appropriate form.
 
-#[derive(Debug)]
-enum DetectedCase {
-    LowerCamelCase,
-    UpperCamelCase,
-    LowerSnakeCase,
-    UpperSnakeCase,
-    Unknown,
-}
-
-fn detect_case(ident: &str) -> DetectedCase {
-    let trimmed_ident = ident.trim_matches('_');
-    let first_lowercase = trimmed_ident.starts_with(|chr: char| chr.is_ascii_lowercase());
-    let mut has_lowercase = first_lowercase;
-    let mut has_uppercase = false;
-    let mut has_underscore = false;
-
-    for chr in trimmed_ident.chars() {
-        if chr == '_' {
-            has_underscore = true;
-        } else if chr.is_ascii_uppercase() {
-            has_uppercase = true;
-        } else if chr.is_ascii_lowercase() {
-            has_lowercase = true;
-        }
-    }
-
-    if has_uppercase {
-        if !has_lowercase {
-            DetectedCase::UpperSnakeCase
-        } else if !has_underscore {
-            if first_lowercase {
-                DetectedCase::LowerCamelCase
-            } else {
-                DetectedCase::UpperCamelCase
-            }
-        } else {
-            // It has uppercase, it has lowercase, it has underscore.
-            // No assumptions here
-            DetectedCase::Unknown
-        }
-    } else {
-        DetectedCase::LowerSnakeCase
-    }
-}
+// Code that was taken from rustc was taken at commit 89fdb30,
+// from file /compiler/rustc_lint/src/nonstandard_style.rs
 
 /// Converts an identifier to an UpperCamelCase form.
 /// Returns `None` if the string is already is UpperCamelCase.
 pub fn to_camel_case(ident: &str) -> Option<String> {
-    let detected_case = detect_case(ident);
-
-    match detected_case {
-        DetectedCase::UpperCamelCase => return None,
-        DetectedCase::LowerCamelCase => {
-            let mut first_capitalized = false;
-            let output = ident
-                .chars()
-                .map(|chr| {
-                    if !first_capitalized && chr.is_ascii_lowercase() {
-                        first_capitalized = true;
-                        chr.to_ascii_uppercase()
-                    } else {
-                        chr
-                    }
-                })
-                .collect();
-            return Some(output);
-        }
-        _ => {}
+    if is_camel_case(ident) {
+        return None;
     }
 
-    let mut output = String::with_capacity(ident.len());
-
-    let mut capital_added = false;
-    for chr in ident.chars() {
-        if chr.is_alphabetic() {
-            if !capital_added {
-                output.push(chr.to_ascii_uppercase());
-                capital_added = true;
-            } else {
-                output.push(chr.to_ascii_lowercase());
+    // Taken from rustc.
+    let ret = ident
+        .trim_matches('_')
+        .split('_')
+        .filter(|component| !component.is_empty())
+        .map(|component| {
+            let mut camel_cased_component = String::new();
+
+            let mut new_word = true;
+            let mut prev_is_lower_case = true;
+
+            for c in component.chars() {
+                // Preserve the case if an uppercase letter follows a lowercase letter, so that
+                // `camelCase` is converted to `CamelCase`.
+                if prev_is_lower_case && c.is_uppercase() {
+                    new_word = true;
+                }
+
+                if new_word {
+                    camel_cased_component.push_str(&c.to_uppercase().to_string());
+                } else {
+                    camel_cased_component.push_str(&c.to_lowercase().to_string());
+                }
+
+                prev_is_lower_case = c.is_lowercase();
+                new_word = false;
             }
-        } else if chr == '_' {
-            // Skip this character and make the next one capital.
-            capital_added = false;
-        } else {
-            // Put the characted as-is.
-            output.push(chr);
-        }
-    }
 
-    if output == ident {
-        // While we didn't detect the correct case at the beginning, there
-        // may be special cases: e.g. `A` is both valid CamelCase and UPPER_SNAKE_CASE.
-        None
-    } else {
-        Some(output)
-    }
+            camel_cased_component
+        })
+        .fold((String::new(), None), |(acc, prev): (String, Option<String>), next| {
+            // separate two components with an underscore if their boundary cannot
+            // be distinguished using a uppercase/lowercase case distinction
+            let join = if let Some(prev) = prev {
+                let l = prev.chars().last().unwrap();
+                let f = next.chars().next().unwrap();
+                !char_has_case(l) && !char_has_case(f)
+            } else {
+                false
+            };
+            (acc + if join { "_" } else { "" } + &next, Some(next))
+        })
+        .0;
+    Some(ret)
 }
 
 /// Converts an identifier to a lower_snake_case form.
 /// Returns `None` if the string is already in lower_snake_case.
 pub fn to_lower_snake_case(ident: &str) -> Option<String> {
-    // First, assume that it's UPPER_SNAKE_CASE.
-    match detect_case(ident) {
-        DetectedCase::LowerSnakeCase => return None,
-        DetectedCase::UpperSnakeCase => {
-            return Some(ident.chars().map(|chr| chr.to_ascii_lowercase()).collect())
-        }
-        _ => {}
+    if is_lower_snake_case(ident) {
+        return None;
+    } else if is_upper_snake_case(ident) {
+        return Some(ident.to_lowercase());
     }
 
-    // Otherwise, assume that it's CamelCase.
-    let lower_snake_case = stdx::to_lower_snake_case(ident);
-
-    if lower_snake_case == ident {
-        // While we didn't detect the correct case at the beginning, there
-        // may be special cases: e.g. `a` is both valid camelCase and snake_case.
-        None
-    } else {
-        Some(lower_snake_case)
-    }
+    Some(stdx::to_lower_snake_case(ident))
 }
 
 /// Converts an identifier to an UPPER_SNAKE_CASE form.
 /// Returns `None` if the string is already is UPPER_SNAKE_CASE.
 pub fn to_upper_snake_case(ident: &str) -> Option<String> {
-    match detect_case(ident) {
-        DetectedCase::UpperSnakeCase => return None,
-        DetectedCase::LowerSnakeCase => {
-            return Some(ident.chars().map(|chr| chr.to_ascii_uppercase()).collect())
-        }
-        _ => {}
+    if is_upper_snake_case(ident) {
+        return None;
+    } else if is_lower_snake_case(ident) {
+        return Some(ident.to_uppercase());
     }
 
-    // Normalize the string from whatever form it's in currently, and then just make it uppercase.
-    let upper_snake_case = stdx::to_upper_snake_case(ident);
+    Some(stdx::to_upper_snake_case(ident))
+}
 
-    if upper_snake_case == ident {
-        // While we didn't detect the correct case at the beginning, there
-        // may be special cases: e.g. `A` is both valid CamelCase and UPPER_SNAKE_CASE.
-        None
-    } else {
-        Some(upper_snake_case)
+// Taken from rustc.
+// Modified by replacing the use of unstable feature `array_windows`.
+fn is_camel_case(name: &str) -> bool {
+    let name = name.trim_matches('_');
+    if name.is_empty() {
+        return true;
     }
+
+    let mut fst = None;
+    // start with a non-lowercase letter rather than non-uppercase
+    // ones (some scripts don't have a concept of upper/lowercase)
+    !name.chars().next().unwrap().is_lowercase()
+        && !name.contains("__")
+        && !name.chars().any(|snd| {
+            let ret = match (fst, snd) {
+                (None, _) => false,
+                (Some(fst), snd) => {
+                    char_has_case(fst) && snd == '_' || char_has_case(snd) && fst == '_'
+                }
+            };
+            fst = Some(snd);
+
+            ret
+        })
+}
+
+fn is_lower_snake_case(ident: &str) -> bool {
+    is_snake_case(ident, char::is_uppercase)
+}
+
+fn is_upper_snake_case(ident: &str) -> bool {
+    is_snake_case(ident, char::is_lowercase)
+}
+
+// Taken from rustc.
+// Modified to allow checking for both upper and lower snake case.
+fn is_snake_case<F: Fn(char) -> bool>(ident: &str, wrong_case: F) -> bool {
+    if ident.is_empty() {
+        return true;
+    }
+    let ident = ident.trim_matches('_');
+
+    let mut allow_underscore = true;
+    ident.chars().all(|c| {
+        allow_underscore = match c {
+            '_' if !allow_underscore => return false,
+            '_' => false,
+            // It would be more obvious to check for the correct case,
+            // but some characters do not have a case.
+            c if !wrong_case(c) => true,
+            _ => return false,
+        };
+        true
+    })
+}
+
+// Taken from rustc.
+fn char_has_case(c: char) -> bool {
+    c.is_lowercase() || c.is_uppercase()
 }
 
 #[cfg(test)]
@@ -167,6 +162,7 @@ mod tests {
         check(to_lower_snake_case, "CamelCase", expect![["camel_case"]]);
         check(to_lower_snake_case, "lowerCamelCase", expect![["lower_camel_case"]]);
         check(to_lower_snake_case, "a", expect![[""]]);
+        check(to_lower_snake_case, "abc", expect![[""]]);
     }
 
     #[test]
@@ -180,6 +176,12 @@ mod tests {
         check(to_camel_case, "Weird_Case", expect![["WeirdCase"]]);
         check(to_camel_case, "name", expect![["Name"]]);
         check(to_camel_case, "A", expect![[""]]);
+        check(to_camel_case, "AABB", expect![[""]]);
+        // Taken from rustc: /compiler/rustc_lint/src/nonstandard_style/tests.rs
+        check(to_camel_case, "X86_64", expect![[""]]);
+        check(to_camel_case, "x86__64", expect![["X86_64"]]);
+        check(to_camel_case, "Abc_123", expect![["Abc123"]]);
+        check(to_camel_case, "A1_b2_c3", expect![["A1B2C3"]]);
     }
 
     #[test]
@@ -190,5 +192,7 @@ mod tests {
         check(to_upper_snake_case, "CamelCase", expect![["CAMEL_CASE"]]);
         check(to_upper_snake_case, "lowerCamelCase", expect![["LOWER_CAMEL_CASE"]]);
         check(to_upper_snake_case, "A", expect![[""]]);
+        check(to_upper_snake_case, "ABC", expect![[""]]);
+        check(to_upper_snake_case, "X86_64", expect![[""]]);
     }
 }
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
index 21a121aad..2da9688ca 100644
--- a/crates/hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -202,4 +202,22 @@ fn main() {
 "#,
         );
     }
+
+    #[test]
+    fn no_missing_unsafe_diagnostic_with_safe_intrinsic() {
+        check_diagnostics(
+            r#"
+extern "rust-intrinsic" {
+    pub fn bitreverse(x: u32) -> u32; // Safe intrinsic
+    pub fn floorf32(x: f32) -> f32; // Unsafe intrinsic
+}
+
+fn main() {
+    let _ = bitreverse(12);
+    let _ = floorf32(12.0);
+          //^^^^^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
+}
+"#,
+        );
+    }
 }
diff --git a/crates/hir_ty/src/traits.rs b/crates/hir_ty/src/traits.rs
index 14cd3a2b4..ce1174cbe 100644
--- a/crates/hir_ty/src/traits.rs
+++ b/crates/hir_ty/src/traits.rs
@@ -5,6 +5,7 @@ use base_db::CrateId;
 use chalk_ir::cast::Cast;
 use chalk_solve::{logging_db::LoggingRustIrDatabase, Solver};
 use hir_def::{lang_item::LangItemTarget, TraitId};
+use stdx::panic_context;
 
 use crate::{db::HirDatabase, DebruijnIndex, Substs};
 
@@ -168,14 +169,23 @@ fn solve(
     };
 
     let mut solve = || {
-        if is_chalk_print() {
-            let logging_db = LoggingRustIrDatabase::new(context);
-            let solution = solver.solve_limited(&logging_db, goal, &should_continue);
-            log::debug!("chalk program:\n{}", logging_db);
+        let _ctx = if is_chalk_debug() || is_chalk_print() {
+            Some(panic_context::enter(format!("solving {:?}", goal)))
+        } else {
+            None
+        };
+        let solution = if is_chalk_print() {
+            let logging_db =
+                LoggingRustIrDatabaseLoggingOnDrop(LoggingRustIrDatabase::new(context));
+            let solution = solver.solve_limited(&logging_db.0, goal, &should_continue);
             solution
         } else {
             solver.solve_limited(&context, goal, &should_continue)
-        }
+        };
+
+        log::debug!("solve({:?}) => {:?}", goal, solution);
+
+        solution
     };
 
     // don't set the TLS for Chalk unless Chalk debugging is active, to make
@@ -183,11 +193,17 @@ fn solve(
     let solution =
         if is_chalk_debug() { chalk::tls::set_current_program(db, solve) } else { solve() };
 
-    log::debug!("solve({:?}) => {:?}", goal, solution);
-
     solution
 }
 
+struct LoggingRustIrDatabaseLoggingOnDrop<'a>(LoggingRustIrDatabase<Interner, ChalkContext<'a>>);
+
+impl<'a> Drop for LoggingRustIrDatabaseLoggingOnDrop<'a> {
+    fn drop(&mut self) {
+        eprintln!("chalk program:\n{}", self.0);
+    }
+}
+
 fn is_chalk_debug() -> bool {
     std::env::var("CHALK_DEBUG").is_ok()
 }
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index be3301313..dd7affcec 100644
--- a/crates/hir_ty/src/traits/chalk/mapping.rs
+++ b/crates/hir_ty/src/traits/chalk/mapping.rs
@@ -4,8 +4,8 @@
 //! conversions.
 
 use chalk_ir::{
-    cast::Cast, fold::shift::Shift, interner::HasInterner, PlaceholderIndex, Scalar, TypeName,
-    UniverseIndex,
+    cast::Cast, fold::shift::Shift, interner::HasInterner, LifetimeData, PlaceholderIndex, Scalar,
+    TypeName, UniverseIndex,
 };
 use chalk_solve::rust_ir;
 
@@ -76,7 +76,7 @@ impl ToChalk for Ty {
                 );
                 let bounded_ty = chalk_ir::DynTy {
                     bounds: make_binders(where_clauses, 1),
-                    lifetime: FAKE_PLACEHOLDER.to_lifetime(&Interner),
+                    lifetime: LifetimeData::Static.intern(&Interner),
                 };
                 chalk_ir::TyData::Dyn(bounded_ty).intern(&Interner)
             }
@@ -161,9 +161,6 @@ impl ToChalk for Ty {
     }
 }
 
-const FAKE_PLACEHOLDER: PlaceholderIndex =
-    PlaceholderIndex { ui: UniverseIndex::ROOT, idx: usize::MAX };
-
 /// We currently don't model lifetimes, but Chalk does. So, we have to insert a
 /// fake lifetime here, because Chalks built-in logic may expect it to be there.
 fn ref_to_chalk(
@@ -172,7 +169,7 @@ fn ref_to_chalk(
     subst: Substs,
 ) -> chalk_ir::Ty<Interner> {
     let arg = subst[0].clone().to_chalk(db);
-    let lifetime = FAKE_PLACEHOLDER.to_lifetime(&Interner);
+    let lifetime = LifetimeData::Static.intern(&Interner);
     chalk_ir::ApplicationTy {
         name: TypeName::Ref(mutability.to_chalk(db)),
         substitution: chalk_ir::Substitution::from_iter(
@@ -205,7 +202,11 @@ fn array_to_chalk(db: &dyn HirDatabase, subst: Substs) -> chalk_ir::Ty<Interner>
         substitution: chalk_ir::Substitution::empty(&Interner),
     }
     .intern(&Interner);
-    let const_ = FAKE_PLACEHOLDER.to_const(&Interner, usize_ty);
+    let const_ = chalk_ir::ConstData {
+        ty: usize_ty,
+        value: chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: () }),
+    }
+    .intern(&Interner);
     chalk_ir::ApplicationTy {
         name: TypeName::Array,
         substitution: chalk_ir::Substitution::from_iter(