Rollup merge of rust-lang#63717 - petrochenkov:eager, r=matthewjasper

Fix nested eager expansions in arguments of `format_args`

Fixes rust-lang#63460
Fixes rust-lang#63685 (regression from making `format_args` opaque - rust-lang#63114)

r? @matthewjasper

src/librustc_resolve/macros.rs

@@ -140,9 +140,23 @@ impl<'a> base::Resolver for Resolver<'a> {
         ImportResolver { r: self }.resolve_imports()
     }
 
-    fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: ExpnId, force: bool)
-                                -> Result<Option<Lrc<SyntaxExtension>>, Indeterminate> {
-        let parent_scope = self.invocation_parent_scopes[&invoc_id];
+    fn resolve_macro_invocation(
+        &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
+    ) -> Result<Option<Lrc<SyntaxExtension>>, Indeterminate> {
+        let invoc_id = invoc.expansion_data.id;
+        let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
+            Some(parent_scope) => *parent_scope,
+            None => {
+                // If there's no entry in the table, then we are resolving an eagerly expanded
+                // macro, which should inherit its parent scope from its eager expansion root -
+                // the macro that requested this eager expansion.
+                let parent_scope = *self.invocation_parent_scopes.get(&eager_expansion_root)
+                    .expect("non-eager expansion without a parent scope");
+                self.invocation_parent_scopes.insert(invoc_id, parent_scope);
+                parent_scope
+            }
+        };
+
         let (path, kind, derives, after_derive) = match invoc.kind {
             InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
                 (&attr.path, MacroKind::Attr, self.arenas.alloc_ast_paths(derives), after_derive),
@@ -161,7 +175,7 @@ impl<'a> base::Resolver for Resolver<'a> {
                         match self.resolve_macro_path(path, Some(MacroKind::Derive),
                                                       &parent_scope, true, force) {
                             Ok((Some(ref ext), _)) if ext.is_derive_copy => {
-                                self.add_derives(invoc.expansion_data.id, SpecialDerives::COPY);
+                                self.add_derives(invoc_id, SpecialDerives::COPY);
                                 return Ok(None);
                             }
                             Err(Determinacy::Undetermined) => result = Err(Indeterminate),
@@ -178,19 +192,15 @@ impl<'a> base::Resolver for Resolver<'a> {
         let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
 
         let span = invoc.span();
-        invoc.expansion_data.id.set_expn_data(
-            ext.expn_data(parent_scope.expansion, span, fast_print_path(path))
-        );
+        invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
 
         if let Res::Def(_, def_id) = res {
             if after_derive {
                 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
             }
-            self.macro_defs.insert(invoc.expansion_data.id, def_id);
-            let normal_module_def_id =
-                self.macro_def_scope(invoc.expansion_data.id).normal_ancestor_id;
-            self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.id,
-                                                            normal_module_def_id);
+            self.macro_defs.insert(invoc_id, def_id);
+            let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
+            self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
         }
 
         Ok(Some(ext))

src/libsyntax/ext/base.rs

@@ -682,8 +682,9 @@ pub trait Resolver {
 
     fn resolve_imports(&mut self);
 
-    fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: ExpnId, force: bool)
-                                -> Result<Option<Lrc<SyntaxExtension>>, Indeterminate>;
+    fn resolve_macro_invocation(
+        &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
+    ) -> Result<Option<Lrc<SyntaxExtension>>, Indeterminate>;
 
     fn check_unused_macros(&self);
 
@@ -908,12 +909,9 @@ impl<'a> ExtCtxt<'a> {
 /// compilation on error, merely emits a non-fatal error and returns `None`.
 pub fn expr_to_spanned_string<'a>(
     cx: &'a mut ExtCtxt<'_>,
-    mut expr: P<ast::Expr>,
+    expr: P<ast::Expr>,
     err_msg: &str,
 ) -> Result<(Symbol, ast::StrStyle, Span), Option<DiagnosticBuilder<'a>>> {
-    // Update `expr.span`'s ctxt now in case expr is an `include!` macro invocation.
-    expr.span = expr.span.apply_mark(cx.current_expansion.id);
-
     // Perform eager expansion on the expression.
     // We want to be able to handle e.g., `concat!("foo", "bar")`.
     let expr = cx.expander().fully_expand_fragment(AstFragment::Expr(expr)).make_expr();

src/libsyntax/ext/expand.rs

@@ -305,9 +305,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 continue
             };
 
-            let scope =
+            let eager_expansion_root =
                 if self.monotonic { invoc.expansion_data.id } else { orig_expansion_data.id };
-            let ext = match self.cx.resolver.resolve_macro_invocation(&invoc, scope, force) {
+            let ext = match self.cx.resolver.resolve_macro_invocation(
+                &invoc, eager_expansion_root, force
+            ) {
                 Ok(ext) => ext,
                 Err(Indeterminate) => {
                     undetermined_invocations.push(invoc);
@@ -318,7 +320,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             progress = true;
             let ExpansionData { depth, id: expn_id, .. } = invoc.expansion_data;
             self.cx.current_expansion = invoc.expansion_data.clone();
-            self.cx.current_expansion.id = scope;
 
             // FIXME(jseyfried): Refactor out the following logic
             let (expanded_fragment, new_invocations) = if let Some(ext) = ext {

src/test/ui/hygiene/eager-from-opaque-2.rs

@@ -0,0 +1,22 @@
+// Regression test for the issue #63460.
+
+// check-pass
+
+#[macro_export]
+macro_rules! separator {
+    () => { "/" };
+}
+
+#[macro_export]
+macro_rules! concat_separator {
+    ( $e:literal, $($other:literal),+ ) => {
+        concat!($e, $crate::separator!(), $crate::concat_separator!($($other),+))
+    };
+    ( $e:literal ) => {
+        $e
+    }
+}
+
+fn main() {
+    println!("{}", concat_separator!(2, 3, 4))
+}

src/test/ui/hygiene/eager-from-opaque.rs

@@ -0,0 +1,20 @@
+// Opaque macro can eagerly expand its input without breaking its resolution.
+// Regression test for issue #63685.
+
+// check-pass
+
+macro_rules! foo {
+    () => {
+        "foo"
+    };
+}
+
+macro_rules! bar {
+    () => {
+        foo!()
+    };
+}
+
+fn main() {
+    format_args!(bar!());
+}

src/test/ui/macros/derive-in-eager-expansion-hang.stderr

@@ -8,6 +8,9 @@ LL | |
 LL | |         ""
 LL | |     }
    | |_____^
+...
+LL |       format_args!(hang!());
+   |                    ------- in this macro invocation
 help: you might be missing a string literal to format with
    |
 LL |     format_args!("{}", hang!());