Create basic support for names case checks and implement function name case check

1 files changed, 173 insertions, 0 deletions

diff --git a/crates/hir_ty/src/diagnostics/decl_check.rs b/crates/hir_ty/src/diagnostics/decl_check.rs
new file mode 100644
index 000000000..6c3cd65c5
--- /dev/null
+++ b/crates/hir_ty/src/diagnostics/decl_check.rs
@@ -0,0 +1,173 @@
+//! Provides validators for the item declarations.
+//! This includes the following items:
+//! - variable bindings (e.g. `let x = foo();`)
+//! - struct fields (e.g. `struct Foo { field: u8 }`)
+//! - enum fields (e.g. `enum Foo { Variant { field: u8 } }`)
+//! - function/method arguments (e.g. `fn foo(arg: u8)`)
+
+// TODO: Temporary, to not see warnings until module is somewhat complete.
+// If you see these lines in the pull request, feel free to call me stupid :P.
+#![allow(dead_code, unused_imports, unused_variables)]
+
+use std::sync::Arc;
+
+use hir_def::{
+    body::Body,
+    db::DefDatabase,
+    expr::{Expr, ExprId, UnaryOp},
+    item_tree::ItemTreeNode,
+    resolver::{resolver_for_expr, ResolveValueResult, ValueNs},
+    src::HasSource,
+    AdtId, FunctionId, Lookup, ModuleDefId,
+};
+use hir_expand::{diagnostics::DiagnosticSink, name::Name};
+use syntax::{ast::NameOwner, AstPtr};
+
+use crate::{
+    db::HirDatabase,
+    diagnostics::{CaseType, IncorrectCase},
+    lower::CallableDefId,
+    ApplicationTy, InferenceResult, Ty, TypeCtor,
+};
+
+pub(super) struct DeclValidator<'a, 'b: 'a> {
+    owner: ModuleDefId,
+    sink: &'a mut DiagnosticSink<'b>,
+}
+
+#[derive(Debug)]
+struct Replacement {
+    current_name: Name,
+    suggested_text: String,
+    expected_case: CaseType,
+}
+
+impl<'a, 'b> DeclValidator<'a, 'b> {
+    pub(super) fn new(
+        owner: ModuleDefId,
+        sink: &'a mut DiagnosticSink<'b>,
+    ) -> DeclValidator<'a, 'b> {
+        DeclValidator { owner, sink }
+    }
+
+    pub(super) fn validate_item(&mut self, db: &dyn HirDatabase) {
+        // let def = self.owner.into();
+        match self.owner {
+            ModuleDefId::FunctionId(func) => self.validate_func(db, func),
+            ModuleDefId::AdtId(adt) => self.validate_adt(db, adt),
+            _ => return,
+        }
+    }
+
+    fn validate_func(&mut self, db: &dyn HirDatabase, func: FunctionId) {
+        let data = db.function_data(func);
+
+        // 1. Check the function name.
+        let function_name = data.name.to_string();
+        let fn_name_replacement = if let Some(new_name) = to_lower_snake_case(&function_name) {
+            let replacement = Replacement {
+                current_name: data.name.clone(),
+                suggested_text: new_name,
+                expected_case: CaseType::LowerSnakeCase,
+            };
+            Some(replacement)
+        } else {
+            None
+        };
+
+        // 2. Check the param names.
+        let mut fn_param_replacements = Vec::new();
+
+        for param_name in data.param_names.iter().cloned().filter_map(|i| i) {
+            let name = param_name.to_string();
+            if let Some(new_name) = to_lower_snake_case(&name) {
+                let replacement = Replacement {
+                    current_name: param_name,
+                    suggested_text: new_name,
+                    expected_case: CaseType::LowerSnakeCase,
+                };
+                fn_param_replacements.push(replacement);
+            }
+        }
+
+        // 3. If there is at least one element to spawn a warning on, go to the source map and generate a warning.
+        self.create_incorrect_case_diagnostic_for_func(
+            func,
+            db,
+            fn_name_replacement,
+            fn_param_replacements,
+        )
+    }
+
+    /// Given the information about incorrect names in the function declaration, looks up into the source code
+    /// for exact locations and adds diagnostics into the sink.
+    fn create_incorrect_case_diagnostic_for_func(
+        &mut self,
+        func: FunctionId,
+        db: &dyn HirDatabase,
+        fn_name_replacement: Option<Replacement>,
+        fn_param_replacements: Vec<Replacement>,
+    ) {
+        // XXX: only look at sources if we do have incorrect names
+        if fn_name_replacement.is_none() && fn_param_replacements.is_empty() {
+            return;
+        }
+
+        let fn_loc = func.lookup(db.upcast());
+        let fn_src = fn_loc.source(db.upcast());
+
+        if let Some(replacement) = fn_name_replacement {
+            let ast_ptr = if let Some(name) = fn_src.value.name() {
+                name
+            } else {
+                // We don't want rust-analyzer to panic over this, but it is definitely some kind of error in the logic.
+                log::error!(
+                    "Replacement was generated for a function without a name: {:?}",
+                    fn_src
+                );
+                return;
+            };
+
+            let diagnostic = IncorrectCase {
+                file: fn_src.file_id,
+                ident: AstPtr::new(&ast_ptr).into(),
+                expected_case: replacement.expected_case,
+                ident_text: replacement.current_name.to_string(),
+                suggested_text: replacement.suggested_text,
+            };
+
+            self.sink.push(diagnostic);
+        }
+
+        // let item_tree = db.item_tree(loc.id.file_id);
+        // let fn_def = &item_tree[fn_loc.id.value];
+        // let (_, source_map) = db.body_with_source_map(func.into());
+    }
+
+    fn validate_adt(&mut self, db: &dyn HirDatabase, adt: AdtId) {}
+}
+
+fn to_lower_snake_case(ident: &str) -> Option<String> {
+    let lower_snake_case = stdx::to_lower_snake_case(ident);
+
+    if lower_snake_case == ident {
+        None
+    } else {
+        Some(lower_snake_case)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::check_diagnostics;
+
+    #[test]
+    fn incorrect_function_name() {
+        check_diagnostics(
+            r#"
+fn NonSnakeCaseName() {}
+// ^^^^^^^^^^^^^^^^ Argument `NonSnakeCaseName` should have a snake_case name, e.g. `non_snake_case_name`
+"#,
+        );
+    }
+}