6 files changed, 194 insertions, 65 deletions

diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index 42c392513..0e136b904 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -76,12 +76,13 @@ fn def_with_body_from_child_node(
     db: &impl HirDatabase,
     child: InFile<&SyntaxNode>,
 ) -> Option<DefWithBody> {
-    child.value.ancestors().find_map(|node| {
+    child.cloned().ancestors_with_macros(db).find_map(|node| {
+        let n = &node.value;
         match_ast! {
-            match node {
-                ast::FnDef(def)  => { return Function::from_source(db, child.with_value(def)).map(DefWithBody::from); },
-                ast::ConstDef(def) => { return Const::from_source(db, child.with_value(def)).map(DefWithBody::from); },
-                ast::StaticDef(def) => { return Static::from_source(db, child.with_value(def)).map(DefWithBody::from); },
+            match n {
+                ast::FnDef(def)  => { return Function::from_source(db, node.with_value(def)).map(DefWithBody::from); },
+                ast::ConstDef(def) => { return Const::from_source(db, node.with_value(def)).map(DefWithBody::from); },
+                ast::StaticDef(def) => { return Static::from_source(db, node.with_value(def)).map(DefWithBody::from); },
                 _ => { None },
             }
         }
@@ -135,6 +136,7 @@ pub struct ReferenceDescriptor {
     pub name: String,
 }
 
+#[derive(Debug)]
 pub struct Expansion {
     macro_file_kind: MacroFileKind,
     macro_call_id: MacroCallId,
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index 35f99b2bc..99303188b 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -49,7 +49,11 @@ register_builtin! {
     (COMPILE_ERROR_MACRO, CompileError) => compile_error_expand,
     (FILE_MACRO, File) => file_expand,
     (LINE_MACRO, Line) => line_expand,
-    (STRINGIFY_MACRO, Stringify) => stringify_expand
+    (STRINGIFY_MACRO, Stringify) => stringify_expand,
+    (FORMAT_ARGS_MACRO, FormatArgs) => format_args_expand,
+    // format_args_nl only differs in that it adds a newline in the end,
+    // so we use the same stub expansion for now
+    (FORMAT_ARGS_NL_MACRO, FormatArgsNl) => format_args_expand
 }
 
 fn to_line_number(db: &dyn AstDatabase, file: HirFileId, pos: TextUnit) -> usize {
@@ -200,6 +204,41 @@ fn compile_error_expand(
     Err(mbe::ExpandError::BindingError("Must be a string".into()))
 }
 
+fn format_args_expand(
+    _db: &dyn AstDatabase,
+    _id: MacroCallId,
+    tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // We expand `format_args!("", arg1, arg2)` to
+    // `std::fmt::Arguments::new_v1(&[], &[&arg1, &arg2])`,
+    // which is still not really correct, but close enough for now
+    let mut args = Vec::new();
+    let mut current = Vec::new();
+    for tt in tt.token_trees.iter().cloned() {
+        match tt {
+            tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => {
+                args.push(tt::Subtree { delimiter: tt::Delimiter::None, token_trees: current });
+                current = Vec::new();
+            }
+            _ => {
+                current.push(tt);
+            }
+        }
+    }
+    if !current.is_empty() {
+        args.push(tt::Subtree { delimiter: tt::Delimiter::None, token_trees: current });
+    }
+    if args.is_empty() {
+        return Err(mbe::ExpandError::NoMatchingRule);
+    }
+    let _format_string = args.remove(0);
+    let arg_tts = args.into_iter().flat_map(|arg| (quote! { & #arg , }).token_trees);
+    let expanded = quote! {
+        std::fmt::Arguments::new_v1(&[], &[##arg_tts])
+    };
+    Ok(expanded)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -307,4 +346,21 @@ mod tests {
 
         assert_eq!(expanded, r#"loop{"error!"}"#);
     }
+
+    #[test]
+    fn test_format_args_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+        #[rustc_builtin_macro]
+        macro_rules! format_args {
+            ($fmt:expr) => ({ /* compiler built-in */ });
+            ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+        }
+        format_args!("{} {:?}", arg1(a, b, c), arg2);
+"#,
+            BuiltinFnLikeExpander::FormatArgs,
+        );
+
+        assert_eq!(expanded, r#"std::fmt::Arguments::new_v1(&[] ,&[&arg1(a,b,c),&arg2,])"#);
+    }
 }
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index 99dabf3fb..013a6c8ba 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -45,8 +45,8 @@ impl TokenExpander {
     pub fn map_id_up(&self, id: tt::TokenId) -> (tt::TokenId, mbe::Origin) {
         match self {
             TokenExpander::MacroRules(it) => it.map_id_up(id),
-            TokenExpander::Builtin(..) => (id, mbe::Origin::Def),
-            TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Def),
+            TokenExpander::Builtin(..) => (id, mbe::Origin::Call),
+            TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Call),
         }
     }
 }
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index 59c69b91b..0a5da7e54 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -76,6 +76,17 @@ impl HirFileId {
         }
     }
 
+    /// If this is a macro call, returns the syntax node of the call.
+    pub fn call_node(self, db: &dyn db::AstDatabase) -> Option<InFile<SyntaxNode>> {
+        match self.0 {
+            HirFileIdRepr::FileId(_) => None,
+            HirFileIdRepr::MacroFile(macro_file) => {
+                let loc = db.lookup_intern_macro(macro_file.macro_call_id);
+                Some(loc.kind.node(db))
+            }
+        }
+    }
+
     /// Return expansion information if it is a macro-expansion file
     pub fn expansion_info(self, db: &dyn db::AstDatabase) -> Option<ExpansionInfo> {
         match self.0 {
@@ -176,6 +187,13 @@ impl MacroCallKind {
         }
     }
 
+    pub fn node(&self, db: &dyn db::AstDatabase) -> InFile<SyntaxNode> {
+        match self {
+            MacroCallKind::FnLike(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
+            MacroCallKind::Attr(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
+        }
+    }
+
     pub fn arg(&self, db: &dyn db::AstDatabase) -> Option<SyntaxNode> {
         match self {
             MacroCallKind::FnLike(ast_id) => {
@@ -283,3 +301,24 @@ impl<T> InFile<T> {
         db.parse_or_expand(self.file_id).expect("source created from invalid file")
     }
 }
+
+impl<T: Clone> InFile<&T> {
+    pub fn cloned(&self) -> InFile<T> {
+        self.with_value(self.value.clone())
+    }
+}
+
+impl InFile<SyntaxNode> {
+    pub fn ancestors_with_macros<'a>(
+        self,
+        db: &'a impl crate::db::AstDatabase,
+    ) -> impl Iterator<Item = InFile<SyntaxNode>> + 'a {
+        std::iter::successors(Some(self), move |node| match node.value.parent() {
+            Some(parent) => Some(node.with_value(parent)),
+            None => {
+                let parent_node = node.file_id.call_node(db)?;
+                Some(parent_node)
+            }
+        })
+    }
+}
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index c5a191160..4f2f702c0 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -38,8 +38,8 @@ impl Name {
     }
 
     /// Shortcut to create inline plain text name
-    const fn new_inline_ascii(len: usize, text: &[u8]) -> Name {
-        Name::new_text(SmolStr::new_inline_from_ascii(len, text))
+    const fn new_inline_ascii(text: &[u8]) -> Name {
+        Name::new_text(SmolStr::new_inline_from_ascii(text.len(), text))
     }
 
     /// Resolve a name from the text of token.
@@ -105,68 +105,70 @@ impl AsName for ra_db::Dependency {
 }
 
 // Primitives
-pub const ISIZE: Name = Name::new_inline_ascii(5, b"isize");
-pub const I8: Name = Name::new_inline_ascii(2, b"i8");
-pub const I16: Name = Name::new_inline_ascii(3, b"i16");
-pub const I32: Name = Name::new_inline_ascii(3, b"i32");
-pub const I64: Name = Name::new_inline_ascii(3, b"i64");
-pub const I128: Name = Name::new_inline_ascii(4, b"i128");
-pub const USIZE: Name = Name::new_inline_ascii(5, b"usize");
-pub const U8: Name = Name::new_inline_ascii(2, b"u8");
-pub const U16: Name = Name::new_inline_ascii(3, b"u16");
-pub const U32: Name = Name::new_inline_ascii(3, b"u32");
-pub const U64: Name = Name::new_inline_ascii(3, b"u64");
-pub const U128: Name = Name::new_inline_ascii(4, b"u128");
-pub const F32: Name = Name::new_inline_ascii(3, b"f32");
-pub const F64: Name = Name::new_inline_ascii(3, b"f64");
-pub const BOOL: Name = Name::new_inline_ascii(4, b"bool");
-pub const CHAR: Name = Name::new_inline_ascii(4, b"char");
-pub const STR: Name = Name::new_inline_ascii(3, b"str");
+pub const ISIZE: Name = Name::new_inline_ascii(b"isize");
+pub const I8: Name = Name::new_inline_ascii(b"i8");
+pub const I16: Name = Name::new_inline_ascii(b"i16");
+pub const I32: Name = Name::new_inline_ascii(b"i32");
+pub const I64: Name = Name::new_inline_ascii(b"i64");
+pub const I128: Name = Name::new_inline_ascii(b"i128");
+pub const USIZE: Name = Name::new_inline_ascii(b"usize");
+pub const U8: Name = Name::new_inline_ascii(b"u8");
+pub const U16: Name = Name::new_inline_ascii(b"u16");
+pub const U32: Name = Name::new_inline_ascii(b"u32");
+pub const U64: Name = Name::new_inline_ascii(b"u64");
+pub const U128: Name = Name::new_inline_ascii(b"u128");
+pub const F32: Name = Name::new_inline_ascii(b"f32");
+pub const F64: Name = Name::new_inline_ascii(b"f64");
+pub const BOOL: Name = Name::new_inline_ascii(b"bool");
+pub const CHAR: Name = Name::new_inline_ascii(b"char");
+pub const STR: Name = Name::new_inline_ascii(b"str");
 
 // Special names
-pub const SELF_PARAM: Name = Name::new_inline_ascii(4, b"self");
-pub const SELF_TYPE: Name = Name::new_inline_ascii(4, b"Self");
-pub const MACRO_RULES: Name = Name::new_inline_ascii(11, b"macro_rules");
+pub const SELF_PARAM: Name = Name::new_inline_ascii(b"self");
+pub const SELF_TYPE: Name = Name::new_inline_ascii(b"Self");
+pub const MACRO_RULES: Name = Name::new_inline_ascii(b"macro_rules");
 
 // Components of known path (value or mod name)
-pub const STD: Name = Name::new_inline_ascii(3, b"std");
-pub const ITER: Name = Name::new_inline_ascii(4, b"iter");
-pub const OPS: Name = Name::new_inline_ascii(3, b"ops");
-pub const FUTURE: Name = Name::new_inline_ascii(6, b"future");
-pub const RESULT: Name = Name::new_inline_ascii(6, b"result");
-pub const BOXED: Name = Name::new_inline_ascii(5, b"boxed");
+pub const STD: Name = Name::new_inline_ascii(b"std");
+pub const ITER: Name = Name::new_inline_ascii(b"iter");
+pub const OPS: Name = Name::new_inline_ascii(b"ops");
+pub const FUTURE: Name = Name::new_inline_ascii(b"future");
+pub const RESULT: Name = Name::new_inline_ascii(b"result");
+pub const BOXED: Name = Name::new_inline_ascii(b"boxed");
 
 // Components of known path (type name)
-pub const INTO_ITERATOR_TYPE: Name = Name::new_inline_ascii(12, b"IntoIterator");
-pub const ITEM_TYPE: Name = Name::new_inline_ascii(4, b"Item");
-pub const TRY_TYPE: Name = Name::new_inline_ascii(3, b"Try");
-pub const OK_TYPE: Name = Name::new_inline_ascii(2, b"Ok");
-pub const FUTURE_TYPE: Name = Name::new_inline_ascii(6, b"Future");
-pub const RESULT_TYPE: Name = Name::new_inline_ascii(6, b"Result");
-pub const OUTPUT_TYPE: Name = Name::new_inline_ascii(6, b"Output");
-pub const TARGET_TYPE: Name = Name::new_inline_ascii(6, b"Target");
-pub const BOX_TYPE: Name = Name::new_inline_ascii(3, b"Box");
-pub const RANGE_FROM_TYPE: Name = Name::new_inline_ascii(9, b"RangeFrom");
-pub const RANGE_FULL_TYPE: Name = Name::new_inline_ascii(9, b"RangeFull");
-pub const RANGE_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(14, b"RangeInclusive");
-pub const RANGE_TO_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(16, b"RangeToInclusive");
-pub const RANGE_TO_TYPE: Name = Name::new_inline_ascii(7, b"RangeTo");
-pub const RANGE_TYPE: Name = Name::new_inline_ascii(5, b"Range");
+pub const INTO_ITERATOR_TYPE: Name = Name::new_inline_ascii(b"IntoIterator");
+pub const ITEM_TYPE: Name = Name::new_inline_ascii(b"Item");
+pub const TRY_TYPE: Name = Name::new_inline_ascii(b"Try");
+pub const OK_TYPE: Name = Name::new_inline_ascii(b"Ok");
+pub const FUTURE_TYPE: Name = Name::new_inline_ascii(b"Future");
+pub const RESULT_TYPE: Name = Name::new_inline_ascii(b"Result");
+pub const OUTPUT_TYPE: Name = Name::new_inline_ascii(b"Output");
+pub const TARGET_TYPE: Name = Name::new_inline_ascii(b"Target");
+pub const BOX_TYPE: Name = Name::new_inline_ascii(b"Box");
+pub const RANGE_FROM_TYPE: Name = Name::new_inline_ascii(b"RangeFrom");
+pub const RANGE_FULL_TYPE: Name = Name::new_inline_ascii(b"RangeFull");
+pub const RANGE_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(b"RangeInclusive");
+pub const RANGE_TO_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(b"RangeToInclusive");
+pub const RANGE_TO_TYPE: Name = Name::new_inline_ascii(b"RangeTo");
+pub const RANGE_TYPE: Name = Name::new_inline_ascii(b"Range");
 
 // Builtin Macros
-pub const FILE_MACRO: Name = Name::new_inline_ascii(4, b"file");
-pub const COLUMN_MACRO: Name = Name::new_inline_ascii(6, b"column");
-pub const COMPILE_ERROR_MACRO: Name = Name::new_inline_ascii(13, b"compile_error");
-pub const LINE_MACRO: Name = Name::new_inline_ascii(4, b"line");
-pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(9, b"stringify");
+pub const FILE_MACRO: Name = Name::new_inline_ascii(b"file");
+pub const COLUMN_MACRO: Name = Name::new_inline_ascii(b"column");
+pub const COMPILE_ERROR_MACRO: Name = Name::new_inline_ascii(b"compile_error");
+pub const LINE_MACRO: Name = Name::new_inline_ascii(b"line");
+pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(b"stringify");
+pub const FORMAT_ARGS_MACRO: Name = Name::new_inline_ascii(b"format_args");
+pub const FORMAT_ARGS_NL_MACRO: Name = Name::new_inline_ascii(b"format_args_nl");
 
 // Builtin derives
-pub const COPY_TRAIT: Name = Name::new_inline_ascii(4, b"Copy");
-pub const CLONE_TRAIT: Name = Name::new_inline_ascii(5, b"Clone");
-pub const DEFAULT_TRAIT: Name = Name::new_inline_ascii(7, b"Default");
-pub const DEBUG_TRAIT: Name = Name::new_inline_ascii(5, b"Debug");
-pub const HASH_TRAIT: Name = Name::new_inline_ascii(4, b"Hash");
-pub const ORD_TRAIT: Name = Name::new_inline_ascii(3, b"Ord");
-pub const PARTIAL_ORD_TRAIT: Name = Name::new_inline_ascii(10, b"PartialOrd");
-pub const EQ_TRAIT: Name = Name::new_inline_ascii(2, b"Eq");
-pub const PARTIAL_EQ_TRAIT: Name = Name::new_inline_ascii(9, b"PartialEq");
+pub const COPY_TRAIT: Name = Name::new_inline_ascii(b"Copy");
+pub const CLONE_TRAIT: Name = Name::new_inline_ascii(b"Clone");
+pub const DEFAULT_TRAIT: Name = Name::new_inline_ascii(b"Default");
+pub const DEBUG_TRAIT: Name = Name::new_inline_ascii(b"Debug");
+pub const HASH_TRAIT: Name = Name::new_inline_ascii(b"Hash");
+pub const ORD_TRAIT: Name = Name::new_inline_ascii(b"Ord");
+pub const PARTIAL_ORD_TRAIT: Name = Name::new_inline_ascii(b"PartialOrd");
+pub const EQ_TRAIT: Name = Name::new_inline_ascii(b"Eq");
+pub const PARTIAL_EQ_TRAIT: Name = Name::new_inline_ascii(b"PartialEq");
diff --git a/crates/ra_ide/src/goto_definition.rs b/crates/ra_ide/src/goto_definition.rs
index 76a741207..d3c198813 100644
--- a/crates/ra_ide/src/goto_definition.rs
+++ b/crates/ra_ide/src/goto_definition.rs
@@ -689,8 +689,38 @@ mod tests {
                     fo<|>o();
                 }
             }
+            mod confuse_index { fn foo(); }
             ",
             "foo FN_DEF FileId(1) [52; 63) [55; 58)",
         );
     }
+
+    #[should_panic] // currently failing because of expr mapping problems
+    #[test]
+    fn goto_through_format() {
+        check_goto(
+            "
+            //- /lib.rs
+            #[macro_export]
+            macro_rules! format {
+                ($($arg:tt)*) => ($crate::fmt::format($crate::__export::format_args!($($arg)*)))
+            }
+            #[rustc_builtin_macro]
+            #[macro_export]
+            macro_rules! format_args {
+                ($fmt:expr) => ({ /* compiler built-in */ });
+                ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+            }
+            pub mod __export {
+                pub use crate::format_args;
+                fn foo() {} // for index confusion
+            }
+            fn foo() -> i8 {}
+            fn test() {
+                format!(\"{}\", fo<|>o())
+            }
+            ",
+            "foo FN_DEF FileId(1) [359; 376) [362; 365)",
+        );
+    }
 }