diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs index 03674978d53d..d05c7811b087 100644 --- a/crates/ide/src/inlay_hints.rs +++ b/crates/ide/src/inlay_hints.rs @@ -307,6 +307,7 @@ pub struct InlayHintsConfig<'a> { pub sized_bound: bool, pub discriminant_hints: DiscriminantHints, pub parameter_hints: bool, + pub parameter_hints_for_missing_arguments: bool, pub generic_parameter_hints: GenericParameterHints, pub chaining_hints: bool, pub adjustment_hints: AdjustmentHints, @@ -886,6 +887,7 @@ mod tests { render_colons: false, type_hints: false, parameter_hints: false, + parameter_hints_for_missing_arguments: false, sized_bound: false, generic_parameter_hints: GenericParameterHints { type_hints: false, diff --git a/crates/ide/src/inlay_hints/param_name.rs b/crates/ide/src/inlay_hints/param_name.rs index 8d0348767316..f1e62a5ab8ac 100644 --- a/crates/ide/src/inlay_hints/param_name.rs +++ b/crates/ide/src/inlay_hints/param_name.rs @@ -11,6 +11,7 @@ use hir::{EditionedFileId, Semantics}; use ide_db::{RootDatabase, famous_defs::FamousDefs}; use stdx::to_lower_snake_case; +use syntax::T; use syntax::ast::{self, AstNode, HasArgList, HasName, UnaryOp}; use crate::{InlayHint, InlayHintLabel, InlayHintPosition, InlayHintsConfig, InlayKind}; @@ -88,9 +89,75 @@ pub(super) fn hints( }); acc.extend(hints); + + // Show hint for the next expected (missing) argument if enabled + if config.parameter_hints_for_missing_arguments { + let provided_args_count = arg_list.args().count(); + let params = callable.params(); + let total_params = params.len(); + + if provided_args_count < total_params + && let Some(next_param) = params.get(provided_args_count) + && let Some(param_name) = next_param.name(sema.db) + { + // Apply heuristics to hide obvious parameter hints + if should_hide_missing_param_hint(unary_function, function_name, param_name.as_str()) { + return Some(()); + } + + // Determine the position for the hint + if let Some(hint_range) = missing_arg_hint_position(&arg_list) { + let colon = if config.render_colons { ":" } else { "" }; + let label = InlayHintLabel::simple( + format!("{}{}", param_name.display(sema.db, krate.edition(sema.db)), colon), + None, + config.lazy_location_opt(|| { + let source = sema.source(next_param.clone())?; + let name_syntax = match source.value.as_ref() { + Either::Left(pat) => pat.name(), + Either::Right(param) => match param.pat()? { + ast::Pat::IdentPat(it) => it.name(), + _ => None, + }, + }?; + sema.original_range_opt(name_syntax.syntax()).map(|frange| { + ide_db::FileRange { + file_id: frange.file_id.file_id(sema.db), + range: frange.range, + } + }) + }), + ); + acc.push(InlayHint { + range: hint_range, + kind: InlayKind::Parameter, + label, + text_edit: None, + position: InlayHintPosition::Before, + pad_left: true, + pad_right: false, + resolve_parent: Some(expr.syntax().text_range()), + }); + } + } + } + Some(()) } +/// Determines the position where the hint for a missing argument should be placed. +/// Returns the range of the token where the hint should appear. +fn missing_arg_hint_position(arg_list: &ast::ArgList) -> Option { + // Always place the hint on the closing paren, so it appears before `)`. + // This way `foo()` becomes `foo(a)` visually with the hint. + arg_list + .syntax() + .children_with_tokens() + .filter_map(|it| it.into_token()) + .find(|t| t.kind() == T![')']) + .map(|t| t.text_range()) +} + fn get_callable<'db>( sema: &Semantics<'db, RootDatabase>, expr: &ast::Expr, @@ -153,6 +220,37 @@ fn should_hide_param_name_hint( is_argument_expr_similar_to_param_name(sema, argument, param_name) } +/// Determines whether to hide the parameter hint for a missing argument. +/// This is a simplified version of `should_hide_param_name_hint` that doesn't +/// require an actual argument expression. +fn should_hide_missing_param_hint( + unary_function: bool, + function_name: Option<&str>, + param_name: &str, +) -> bool { + let param_name = param_name.trim_matches('_'); + if param_name.is_empty() { + return true; + } + + if param_name.starts_with("ra_fixture") { + return true; + } + + if unary_function { + if let Some(function_name) = function_name + && is_param_name_suffix_of_fn_name(param_name, function_name) + { + return true; + } + if is_obvious_param(param_name) { + return true; + } + } + + false +} + /// Hide the parameter name of a unary function if it is a `_` - prefixed suffix of the function's name, or equal. /// /// `fn strip_suffix(suffix)` will be hidden. @@ -606,6 +704,103 @@ fn main() { // ^^^^^^ a_d_e baz(a.d.ec); // ^^^^^^ a_d_e +}"#, + ); + } + + #[track_caller] + fn check_missing_params(#[rust_analyzer::rust_fixture] ra_fixture: &str) { + check_with_config( + InlayHintsConfig { + parameter_hints: true, + parameter_hints_for_missing_arguments: true, + ..DISABLED_CONFIG + }, + ra_fixture, + ); + } + + #[test] + fn missing_param_hint_empty_call() { + // When calling foo() with no args, show hint for first param on the closing paren + check_missing_params( + r#" +fn foo(a: i32, b: i32) -> i32 { a + b } +fn main() { + foo(); + //^ a +}"#, + ); + } + + #[test] + fn missing_param_hint_after_first_arg() { + // foo(1,) - show hint for 'a' on '1', and 'b' on the trailing comma + check_missing_params( + r#" +fn foo(a: i32, b: i32) -> i32 { a + b } +fn main() { + foo(1,); + //^ a + //^ b +}"#, + ); + } + + #[test] + fn missing_param_hint_partial_args() { + // foo(1, 2,) - show hints for a, b on args, and c on trailing comma + check_missing_params( + r#" +fn foo(a: i32, b: i32, c: i32) -> i32 { a + b + c } +fn main() { + foo(1, 2,); + //^ a + //^ b + //^ c +}"#, + ); + } + + #[test] + fn missing_param_hint_method_call() { + // S.foo(1,) - show hint for 'a' on '1', and 'b' on trailing comma + check_missing_params( + r#" +struct S; +impl S { + fn foo(&self, a: i32, b: i32) -> i32 { a + b } +} +fn main() { + S.foo(1,); + //^ a + //^ b +}"#, + ); + } + + #[test] + fn missing_param_hint_no_hint_when_complete() { + // When all args provided, no missing hint - just regular param hints + check_missing_params( + r#" +fn foo(a: i32, b: i32) -> i32 { a + b } +fn main() { + foo(1, 2); + //^ a + //^ b +}"#, + ); + } + + #[test] + fn missing_param_hint_respects_heuristics() { + // The hint should be hidden if it matches heuristics (e.g., single param unary fn with same name) + check_missing_params( + r#" +fn foo(foo: i32) -> i32 { foo } +fn main() { + foo(); }"#, ); } diff --git a/crates/ide/src/static_index.rs b/crates/ide/src/static_index.rs index 30e8d62ea210..e87766376acb 100644 --- a/crates/ide/src/static_index.rs +++ b/crates/ide/src/static_index.rs @@ -169,6 +169,7 @@ impl StaticIndex<'_> { type_hints: true, sized_bound: false, parameter_hints: true, + parameter_hints_for_missing_arguments: false, generic_parameter_hints: crate::GenericParameterHints { type_hints: false, lifetime_hints: false, diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs index f39ab1301f8f..1a6cd784cf2f 100644 --- a/crates/rust-analyzer/src/cli/analysis_stats.rs +++ b/crates/rust-analyzer/src/cli/analysis_stats.rs @@ -1205,6 +1205,7 @@ impl flags::AnalysisStats { sized_bound: false, discriminant_hints: ide::DiscriminantHints::Always, parameter_hints: true, + parameter_hints_for_missing_arguments: false, generic_parameter_hints: ide::GenericParameterHints { type_hints: true, lifetime_hints: true, diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs index 1a2ea97204aa..007725be7406 100644 --- a/crates/rust-analyzer/src/config.rs +++ b/crates/rust-analyzer/src/config.rs @@ -280,6 +280,9 @@ config_data! { /// Show function parameter name inlay hints at the call site. inlayHints_parameterHints_enable: bool = true, + /// Show parameter name inlay hints for missing arguments at the call site. + inlayHints_parameterHints_missingArguments_enable: bool = false, + /// Show exclusive range inlay hints. inlayHints_rangeExclusiveHints_enable: bool = false, @@ -1916,6 +1919,9 @@ impl Config { type_hints: self.inlayHints_typeHints_enable().to_owned(), sized_bound: self.inlayHints_implicitSizedBoundHints_enable().to_owned(), parameter_hints: self.inlayHints_parameterHints_enable().to_owned(), + parameter_hints_for_missing_arguments: self + .inlayHints_parameterHints_missingArguments_enable() + .to_owned(), generic_parameter_hints: GenericParameterHints { type_hints: self.inlayHints_genericParameterHints_type_enable().to_owned(), lifetime_hints: self.inlayHints_genericParameterHints_lifetime_enable().to_owned(), diff --git a/docs/book/src/configuration_generated.md b/docs/book/src/configuration_generated.md index b36576b4bb20..1f5c672233ae 100644 --- a/docs/book/src/configuration_generated.md +++ b/docs/book/src/configuration_generated.md @@ -1070,6 +1070,13 @@ Default: `true` Show function parameter name inlay hints at the call site. +## rust-analyzer.inlayHints.parameterHints.missingArguments.enable {#inlayHints.parameterHints.missingArguments.enable} + +Default: `false` + +Show parameter name inlay hints for missing arguments at the call site. + + ## rust-analyzer.inlayHints.rangeExclusiveHints.enable {#inlayHints.rangeExclusiveHints.enable} Default: `false` diff --git a/editors/code/package.json b/editors/code/package.json index abe85d6c9d72..98fe6a558b80 100644 --- a/editors/code/package.json +++ b/editors/code/package.json @@ -2396,6 +2396,16 @@ } } }, + { + "title": "Inlay Hints", + "properties": { + "rust-analyzer.inlayHints.parameterHints.missingArguments.enable": { + "markdownDescription": "Show parameter name inlay hints for missing arguments at the call site.", + "default": false, + "type": "boolean" + } + } + }, { "title": "Inlay Hints", "properties": {