5 files changed, 66 insertions, 16 deletions

diff --git a/crates/ra_hir_expand/src/builtin_derive.rs b/crates/ra_hir_expand/src/builtin_derive.rs
index e60f879a3..1dc9cac66 100644
--- a/crates/ra_hir_expand/src/builtin_derive.rs
+++ b/crates/ra_hir_expand/src/builtin_derive.rs
@@ -38,7 +38,7 @@ macro_rules! register_builtin {
                  _ => return None,
             };
 
-            Some(MacroDefId { krate: None, ast_id: None, kind: MacroDefKind::BuiltInDerive(kind) })
+            Some(MacroDefId { krate: None, ast_id: None, kind: MacroDefKind::BuiltInDerive(kind), local_inner: false })
         }
     };
 }
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index e0fef613d..3bce8f673 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -73,11 +73,13 @@ pub fn find_builtin_macro(
             krate: Some(krate),
             ast_id: Some(ast_id),
             kind: MacroDefKind::BuiltIn(kind),
+            local_inner: false,
         }),
         Either::Right(kind) => Some(MacroDefId {
             krate: Some(krate),
             ast_id: Some(ast_id),
             kind: MacroDefKind::BuiltInEager(kind),
+            local_inner: false,
         }),
     }
 }
@@ -358,7 +360,7 @@ fn env_expand(
     // However, we cannot use an empty string here, because for
     // `include!(concat!(env!("OUT_DIR"), "/foo.rs"))` will become
     // `include!("foo.rs"), which might go to infinite loop
-    let s = get_env_inner(db, arg_id, &key).unwrap_or_else(|| "__RA_UNIMPLEMENTATED__".to_string());
+    let s = get_env_inner(db, arg_id, &key).unwrap_or_else(|| "__RA_UNIMPLEMENTED__".to_string());
     let expanded = quote! { #s };
 
     Ok((expanded, FragmentKind::Expr))
@@ -406,6 +408,7 @@ mod tests {
                     krate: Some(CrateId(0)),
                     ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[0]))),
                     kind: MacroDefKind::BuiltIn(expander),
+                    local_inner: false,
                 };
 
                 let loc = MacroCallLoc {
@@ -425,6 +428,7 @@ mod tests {
                     krate: Some(CrateId(0)),
                     ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[0]))),
                     kind: MacroDefKind::BuiltInEager(expander),
+                    local_inner: false,
                 };
 
                 let args = macro_calls[1].token_tree().unwrap();
@@ -504,7 +508,7 @@ mod tests {
             "#,
         );
 
-        assert_eq!(expanded, "\"__RA_UNIMPLEMENTATED__\"");
+        assert_eq!(expanded, "\"__RA_UNIMPLEMENTED__\"");
     }
 
     #[test]
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index 047452306..bf30d7151 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -34,7 +34,12 @@ impl TokenExpander {
             // FIXME switch these to ExpandResult as well
             TokenExpander::Builtin(it) => it.expand(db, id, tt).into(),
             TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt).into(),
-            TokenExpander::ProcMacro(it) => it.expand(db, id, tt).into(),
+            TokenExpander::ProcMacro(_) => {
+                // We store the result in salsa db to prevent non-determinisc behavior in
+                // some proc-macro implementation
+                // See #4315 for details
+                db.expand_proc_macro(id.into()).into()
+            }
         }
     }
 
@@ -75,6 +80,8 @@ pub trait AstDatabase: SourceDatabase {
 
     #[salsa::interned]
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
+
+    fn expand_proc_macro(&self, call: MacroCallId) -> Result<tt::Subtree, mbe::ExpandError>;
 }
 
 /// This expands the given macro call, but with different arguments. This is
@@ -216,6 +223,33 @@ fn macro_expand_with_arg(
     (Some(Arc::new(tt)), err.map(|e| format!("{:?}", e)))
 }
 
+pub(crate) fn expand_proc_macro(
+    db: &dyn AstDatabase,
+    id: MacroCallId,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    let lazy_id = match id {
+        MacroCallId::LazyMacro(id) => id,
+        MacroCallId::EagerMacro(_) => unreachable!(),
+    };
+
+    let loc = db.lookup_intern_macro(lazy_id);
+    let macro_arg = match db.macro_arg(id) {
+        Some(it) => it,
+        None => {
+            return Err(
+                tt::ExpansionError::Unknown("No arguments for proc-macro".to_string()).into()
+            )
+        }
+    };
+
+    let expander = match loc.def.kind {
+        MacroDefKind::CustomDerive(expander) => expander,
+        _ => unreachable!(),
+    };
+
+    expander.expand(db, lazy_id, &macro_arg.0)
+}
+
 pub(crate) fn parse_or_expand(db: &dyn AstDatabase, file_id: HirFileId) -> Option<SyntaxNode> {
     match file_id.0 {
         HirFileIdRepr::FileId(file_id) => Some(db.parse(file_id).tree().syntax().clone()),
@@ -330,7 +364,7 @@ fn to_fragment_kind(db: &dyn AstDatabase, id: MacroCallId) -> FragmentKind {
             FragmentKind::Expr
         }
         // FIXME: Expand to statements in appropriate positions; HIR lowering needs to handle that
-        EXPR_STMT | BLOCK => FragmentKind::Expr,
+        EXPR_STMT | BLOCK_EXPR => FragmentKind::Expr,
         ARG_LIST => FragmentKind::Expr,
         TRY_EXPR => FragmentKind::Expr,
         TUPLE_EXPR => FragmentKind::Expr,
@@ -342,7 +376,6 @@ fn to_fragment_kind(db: &dyn AstDatabase, id: MacroCallId) -> FragmentKind {
         CONDITION => FragmentKind::Expr,
         BREAK_EXPR => FragmentKind::Expr,
         RETURN_EXPR => FragmentKind::Expr,
-        BLOCK_EXPR => FragmentKind::Expr,
         MATCH_EXPR => FragmentKind::Expr,
         MATCH_ARM => FragmentKind::Expr,
         MATCH_GUARD => FragmentKind::Expr,
diff --git a/crates/ra_hir_expand/src/hygiene.rs b/crates/ra_hir_expand/src/hygiene.rs
index 53866bbcb..6b482a60c 100644
--- a/crates/ra_hir_expand/src/hygiene.rs
+++ b/crates/ra_hir_expand/src/hygiene.rs
@@ -16,31 +16,34 @@ use crate::{
 pub struct Hygiene {
     // This is what `$crate` expands to
     def_crate: Option<CrateId>,
+
+    // Indiciate this is a local inner macro
+    local_inner: bool,
 }
 
 impl Hygiene {
     pub fn new(db: &dyn AstDatabase, file_id: HirFileId) -> Hygiene {
-        let def_crate = match file_id.0 {
-            HirFileIdRepr::FileId(_) => None,
+        let (def_crate, local_inner) = match file_id.0 {
+            HirFileIdRepr::FileId(_) => (None, false),
             HirFileIdRepr::MacroFile(macro_file) => match macro_file.macro_call_id {
                 MacroCallId::LazyMacro(id) => {
                     let loc = db.lookup_intern_macro(id);
                     match loc.def.kind {
-                        MacroDefKind::Declarative => loc.def.krate,
-                        MacroDefKind::BuiltIn(_) => None,
-                        MacroDefKind::BuiltInDerive(_) => None,
-                        MacroDefKind::BuiltInEager(_) => None,
-                        MacroDefKind::CustomDerive(_) => None,
+                        MacroDefKind::Declarative => (loc.def.krate, loc.def.local_inner),
+                        MacroDefKind::BuiltIn(_) => (None, false),
+                        MacroDefKind::BuiltInDerive(_) => (None, false),
+                        MacroDefKind::BuiltInEager(_) => (None, false),
+                        MacroDefKind::CustomDerive(_) => (None, false),
                     }
                 }
-                MacroCallId::EagerMacro(_id) => None,
+                MacroCallId::EagerMacro(_id) => (None, false),
             },
         };
-        Hygiene { def_crate }
+        Hygiene { def_crate, local_inner }
     }
 
     pub fn new_unhygienic() -> Hygiene {
-        Hygiene { def_crate: None }
+        Hygiene { def_crate: None, local_inner: false }
     }
 
     // FIXME: this should just return name
@@ -52,4 +55,12 @@ impl Hygiene {
         }
         Either::Left(name_ref.as_name())
     }
+
+    pub fn local_inner_macros(&self) -> Option<CrateId> {
+        if self.local_inner {
+            self.def_crate
+        } else {
+            None
+        }
+    }
 }
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index 754a0f005..f440c073b 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -204,6 +204,8 @@ pub struct MacroDefId {
     pub krate: Option<CrateId>,
     pub ast_id: Option<AstId<ast::MacroCall>>,
     pub kind: MacroDefKind,
+
+    pub local_inner: bool,
 }
 
 impl MacroDefId {