Implicit format args support

Author: Veykril

crates/hir-def/src/body.rs

@@ -95,6 +95,8 @@ pub struct BodySourceMap {
     field_map_back: FxHashMap<ExprId, FieldSource>,
     pat_field_map_back: FxHashMap<PatId, PatFieldSource>,
 
+    format_args_template_map: FxHashMap<ExprId, Vec<(syntax::TextRange, Name)>>,
+
     expansions: FxHashMap<InFile<AstPtr<ast::MacroCall>>, HirFileId>,
 
     /// Diagnostics accumulated during body lowering. These contain `AstPtr`s and so are stored in
@@ -387,6 +389,14 @@ impl BodySourceMap {
         self.expr_map.get(&src).copied()
     }
 
+    pub fn implicit_format_args(
+        &self,
+        node: InFile<&ast::FormatArgsExpr>,
+    ) -> Option<&[(syntax::TextRange, Name)]> {
+        let src = node.map(AstPtr::new).map(AstPtr::upcast::<ast::Expr>);
+        self.format_args_template_map.get(self.expr_map.get(&src)?).map(std::ops::Deref::deref)
+    }
+
     /// Get a reference to the body source map's diagnostics.
     pub fn diagnostics(&self) -> &[BodyDiagnostic] {
         &self.diagnostics
@@ -403,8 +413,10 @@ impl BodySourceMap {
             field_map_back,
             pat_field_map_back,
             expansions,
+            format_args_template_map,
             diagnostics,
         } = self;
+        format_args_template_map.shrink_to_fit();
         expr_map.shrink_to_fit();
         expr_map_back.shrink_to_fit();
         pat_map.shrink_to_fit();

crates/hir-def/src/body/lower.rs

@@ -1597,12 +1597,20 @@ impl ExprCollector<'_> {
         });
         let template = f.template();
         let fmt_snippet = template.as_ref().map(ToString::to_string);
+        let mut mappings = vec![];
         let fmt = match template.and_then(|it| self.expand_macros_to_string(it)) {
-            Some((s, is_direct_literal)) => {
-                format_args::parse(&s, fmt_snippet, args, is_direct_literal, |name| {
-                    self.alloc_expr_desugared(Expr::Path(Path::from(name)))
-                })
-            }
+            Some((s, is_direct_literal)) => format_args::parse(
+                &s,
+                fmt_snippet,
+                args,
+                is_direct_literal,
+                |name| self.alloc_expr_desugared(Expr::Path(Path::from(name))),
+                |name, span| {
+                    if let Some(span) = span {
+                        mappings.push((span, name.clone()))
+                    }
+                },
+            ),
             None => FormatArgs { template: Default::default(), arguments: args.finish() },
         };
 
@@ -1746,14 +1754,16 @@ impl ExprCollector<'_> {
             tail: Some(unsafe_arg_new),
         });
 
-        self.alloc_expr(
+        let idx = self.alloc_expr(
             Expr::Call {
                 callee: new_v1_formatted,
                 args: Box::new([lit_pieces, args, format_options, unsafe_arg_new]),
                 is_assignee_expr: false,
             },
             syntax_ptr,
-        )
+        );
+        self.source_map.format_args_template_map.insert(idx, mappings);
+        idx
     }
 
     /// Generate a hir expression for a format_args placeholder specification.

crates/hir-def/src/body/tests.rs

@@ -160,7 +160,7 @@ fn main() {
             let count = 10;
             builtin#lang(Arguments::new_v1_formatted)(
                 &[
-                    "\"hello ", " ", " friends, we ", " ", "", "\"",
+                    "hello ", " ", " friends, we ", " ", "",
                 ],
                 &[
                     builtin#lang(Argument::new_display)(
@@ -261,7 +261,7 @@ impl SsrError {
             _ = $crate::error::SsrError::new(
                 builtin#lang(Arguments::new_v1_formatted)(
                     &[
-                        "\"Failed to resolve path `", "`\"",
+                        "Failed to resolve path `", "`",
                     ],
                     &[
                         builtin#lang(Argument::new_display)(
@@ -320,7 +320,7 @@ fn f() {
             $crate::panicking::panic_fmt(
                 builtin#lang(Arguments::new_v1_formatted)(
                     &[
-                        "\"cc\"",
+                        "cc",
                     ],
                     &[],
                     &[],

crates/hir-def/src/hir/format_args.rs

@@ -5,7 +5,7 @@ use hir_expand::name::Name;
 use rustc_dependencies::parse_format as parse;
 use syntax::{
     ast::{self, IsString},
-    AstToken, SmolStr, TextRange,
+    SmolStr, TextRange, TextSize,
 };
 
 use crate::hir::ExprId;
@@ -170,15 +170,18 @@ pub(crate) fn parse(
     mut args: FormatArgumentsCollector,
     is_direct_literal: bool,
     mut synth: impl FnMut(Name) -> ExprId,
+    mut record_usage: impl FnMut(Name, Option<TextRange>),
 ) -> FormatArgs {
-    let text = s.text();
+    let text = s.text_without_quotes();
     let str_style = match s.quote_offsets() {
         Some(offsets) => {
             let raw = u32::from(offsets.quotes.0.len()) - 1;
-            (raw != 0).then_some(raw as usize)
+            // subtract 1 for the `r` prefix
+            (raw != 0).then(|| raw as usize - 1)
         }
         None => None,
     };
+
     let mut parser =
         parse::Parser::new(text, str_style, fmt_snippet, false, parse::ParseMode::Format);
 
@@ -199,6 +202,7 @@ pub(crate) fn parse(
     let to_span = |inner_span: parse::InnerSpan| {
         is_source_literal.then(|| {
             TextRange::new(inner_span.start.try_into().unwrap(), inner_span.end.try_into().unwrap())
+                - TextSize::from(str_style.map(|it| it + 1).unwrap_or(0) as u32 + 1)
         })
     };
 
@@ -230,9 +234,10 @@ pub(crate) fn parse(
                     Err(index)
                 }
             }
-            ArgRef::Name(name, _span) => {
+            ArgRef::Name(name, span) => {
                 let name = Name::new_text_dont_use(SmolStr::new(name));
                 if let Some((index, _)) = args.by_name(&name) {
+                    record_usage(name, span);
                     // Name found in `args`, so we resolve it to its index.
                     if index < args.explicit_args().len() {
                         // Mark it as used, if it was an explicit argument.
@@ -246,6 +251,7 @@ pub(crate) fn parse(
                         // disabled (see RFC #2795)
                         // FIXME: Diagnose
                     }
+                    record_usage(name.clone(), span);
                     Ok(args.add(FormatArgument {
                         kind: FormatArgumentKind::Captured(name.clone()),
                         // FIXME: This is problematic, we might want to synthesize a dummy

crates/hir/src/semantics.rs

@@ -29,8 +29,9 @@ use smallvec::{smallvec, SmallVec};
 use stdx::TupleExt;
 use syntax::{
     algo::skip_trivia_token,
-    ast::{self, HasAttrs as _, HasGenericParams, HasLoopBody},
-    match_ast, AstNode, Direction, SyntaxKind, SyntaxNode, SyntaxNodePtr, SyntaxToken, TextSize,
+    ast::{self, HasAttrs as _, HasGenericParams, HasLoopBody, IsString as _},
+    match_ast, AstNode, AstToken, Direction, SyntaxKind, SyntaxNode, SyntaxNodePtr, SyntaxToken,
+    TextRange, TextSize,
 };
 
 use crate::{
@@ -49,7 +50,7 @@ pub enum DescendPreference {
     None,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum PathResolution {
     /// An item
     Def(ModuleDef),
@@ -402,6 +403,41 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
+    pub fn resolve_offset_in_format_args(
+        &self,
+        string: ast::String,
+        offset: TextSize,
+    ) -> Option<(TextRange, Option<PathResolution>)> {
+        debug_assert!(offset <= string.syntax().text_range().len());
+        let literal = string.syntax().parent().filter(|it| it.kind() == SyntaxKind::LITERAL)?;
+        let format_args = ast::FormatArgsExpr::cast(literal.parent()?)?;
+        let source_analyzer = &self.analyze_no_infer(format_args.syntax())?;
+        let format_args = self.wrap_node_infile(format_args);
+        source_analyzer.resolve_offset_in_format_args(self.db, format_args.as_ref(), offset)
+    }
+
+    pub fn check_for_format_args_template(
+        &self,
+        original_token: SyntaxToken,
+        offset: TextSize,
+    ) -> Option<(TextRange, Option<PathResolution>)> {
+        if let Some(original_string) = ast::String::cast(original_token.clone()) {
+            if let Some(quote) = original_string.open_quote_text_range() {
+                return self
+                    .descend_into_macros(DescendPreference::SameText, original_token.clone())
+                    .into_iter()
+                    .find_map(|token| {
+                        self.resolve_offset_in_format_args(
+                            ast::String::cast(token)?,
+                            offset - quote.end(),
+                        )
+                    })
+                    .map(|(range, res)| (range + quote.end(), res));
+            }
+        }
+        None
+    }
+
     /// Maps a node down by mapping its first and last token down.
     pub fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
         // This might not be the correct way to do this, but it works for now
@@ -419,24 +455,27 @@ impl<'db> SemanticsImpl<'db> {
 
         if first == last {
             // node is just the token, so descend the token
-            self.descend_into_macros_impl(first, 0.into(), &mut |InFile { value, .. }| {
-                if let Some(node) = value.parent_ancestors().find_map(N::cast) {
+            self.descend_into_macros_impl(first, &mut |InFile { value, .. }| {
+                if let Some(node) = value
+                    .parent_ancestors()
+                    .take_while(|it| it.text_range() == value.text_range())
+                    .find_map(N::cast)
+                {
                     res.push(node)
                 }
                 ControlFlow::Continue(())
             });
         } else {
             // Descend first and last token, then zip them to look for the node they belong to
             let mut scratch: SmallVec<[_; 1]> = smallvec![];
-            self.descend_into_macros_impl(first, 0.into(), &mut |token| {
+            self.descend_into_macros_impl(first, &mut |token| {
                 scratch.push(token);
                 ControlFlow::Continue(())
             });
 
             let mut scratch = scratch.into_iter();
             self.descend_into_macros_impl(
                 last,
-                0.into(),
                 &mut |InFile { value: last, file_id: last_fid }| {
                     if let Some(InFile { value: first, file_id: first_fid }) = scratch.next() {
                         if first_fid == last_fid {
@@ -467,7 +506,6 @@ impl<'db> SemanticsImpl<'db> {
         &self,
         mode: DescendPreference,
         token: SyntaxToken,
-        offset: TextSize,
     ) -> SmallVec<[SyntaxToken; 1]> {
         enum Dp<'t> {
             SameText(&'t str),
@@ -487,7 +525,7 @@ impl<'db> SemanticsImpl<'db> {
             DescendPreference::None => Dp::None,
         };
         let mut res = smallvec![];
-        self.descend_into_macros_impl(token.clone(), offset, &mut |InFile { value, .. }| {
+        self.descend_into_macros_impl(token.clone(), &mut |InFile { value, .. }| {
             let is_a_match = match mode {
                 Dp::SameText(text) => value.text() == text,
                 Dp::SameKind(preferred_kind) => {
@@ -513,7 +551,6 @@ impl<'db> SemanticsImpl<'db> {
         &self,
         mode: DescendPreference,
         token: SyntaxToken,
-        offset: TextSize,
     ) -> SyntaxToken {
         enum Dp<'t> {
             SameText(&'t str),
@@ -533,7 +570,7 @@ impl<'db> SemanticsImpl<'db> {
             DescendPreference::None => Dp::None,
         };
         let mut res = token.clone();
-        self.descend_into_macros_impl(token.clone(), offset, &mut |InFile { value, .. }| {
+        self.descend_into_macros_impl(token.clone(), &mut |InFile { value, .. }| {
             let is_a_match = match mode {
                 Dp::SameText(text) => value.text() == text,
                 Dp::SameKind(preferred_kind) => {
@@ -558,9 +595,6 @@ impl<'db> SemanticsImpl<'db> {
     fn descend_into_macros_impl(
         &self,
         token: SyntaxToken,
-        // FIXME: We might want this to be Option<TextSize> to be able to opt out of subrange
-        // mapping, specifically for node downmapping
-        _offset: TextSize,
         f: &mut dyn FnMut(InFile<SyntaxToken>) -> ControlFlow<()>,
     ) {
         // FIXME: Clean this up
@@ -729,7 +763,7 @@ impl<'db> SemanticsImpl<'db> {
         offset: TextSize,
     ) -> impl Iterator<Item = impl Iterator<Item = SyntaxNode> + '_> + '_ {
         node.token_at_offset(offset)
-            .map(move |token| self.descend_into_macros(DescendPreference::None, token, offset))
+            .map(move |token| self.descend_into_macros(DescendPreference::None, token))
             .map(|descendants| {
                 descendants.into_iter().map(move |it| self.token_ancestors_with_macros(it))
             })

crates/hir/src/source_analyzer.rs

@@ -820,6 +820,29 @@ impl SourceAnalyzer {
         false
     }
 
+    pub(crate) fn resolve_offset_in_format_args(
+        &self,
+        db: &dyn HirDatabase,
+        format_args: InFile<&ast::FormatArgsExpr>,
+        offset: TextSize,
+    ) -> Option<(TextRange, Option<PathResolution>)> {
+        let implicits = self.body_source_map()?.implicit_format_args(format_args)?;
+        implicits.iter().find(|(range, _)| range.contains_inclusive(offset)).map(|(range, name)| {
+            (
+                *range,
+                resolve_hir_value_path(
+                    db,
+                    &self.resolver,
+                    self.resolver.body_owner(),
+                    &Path::from_known_path_with_no_generic(ModPath::from_segments(
+                        PathKind::Plain,
+                        Some(name.clone()),
+                    )),
+                ),
+            )
+        })
+    }
+
     fn resolve_impl_method_or_trait_def(
         &self,
         db: &dyn HirDatabase,
@@ -1038,24 +1061,7 @@ fn resolve_hir_path_(
     };
 
     let body_owner = resolver.body_owner();
-    let values = || {
-        resolver.resolve_path_in_value_ns_fully(db.upcast(), path).and_then(|val| {
-            let res = match val {
-                ValueNs::LocalBinding(binding_id) => {
-                    let var = Local { parent: body_owner?, binding_id };
-                    PathResolution::Local(var)
-                }
-                ValueNs::FunctionId(it) => PathResolution::Def(Function::from(it).into()),
-                ValueNs::ConstId(it) => PathResolution::Def(Const::from(it).into()),
-                ValueNs::StaticId(it) => PathResolution::Def(Static::from(it).into()),
-                ValueNs::StructId(it) => PathResolution::Def(Struct::from(it).into()),
-                ValueNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
-                ValueNs::ImplSelf(impl_id) => PathResolution::SelfType(impl_id.into()),
-                ValueNs::GenericParam(id) => PathResolution::ConstParam(id.into()),
-            };
-            Some(res)
-        })
-    };
+    let values = || resolve_hir_value_path(db, resolver, body_owner, path);
 
     let items = || {
         resolver
@@ -1075,6 +1081,30 @@ fn resolve_hir_path_(
         .or_else(macros)
 }
 
+fn resolve_hir_value_path(
+    db: &dyn HirDatabase,
+    resolver: &Resolver,
+    body_owner: Option<DefWithBodyId>,
+    path: &Path,
+) -> Option<PathResolution> {
+    resolver.resolve_path_in_value_ns_fully(db.upcast(), path).and_then(|val| {
+        let res = match val {
+            ValueNs::LocalBinding(binding_id) => {
+                let var = Local { parent: body_owner?, binding_id };
+                PathResolution::Local(var)
+            }
+            ValueNs::FunctionId(it) => PathResolution::Def(Function::from(it).into()),
+            ValueNs::ConstId(it) => PathResolution::Def(Const::from(it).into()),
+            ValueNs::StaticId(it) => PathResolution::Def(Static::from(it).into()),
+            ValueNs::StructId(it) => PathResolution::Def(Struct::from(it).into()),
+            ValueNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
+            ValueNs::ImplSelf(impl_id) => PathResolution::SelfType(impl_id.into()),
+            ValueNs::GenericParam(id) => PathResolution::ConstParam(id.into()),
+        };
+        Some(res)
+    })
+}
+
 /// Resolves a path where we know it is a qualifier of another path.
 ///
 /// For example, if we have: