Check for macros in built-in attributes that don't support them.

Author: ehuss

Diff for: compiler/rustc_expand/src/module.rs

@@ -3,6 +3,7 @@ use rustc_ast::ptr::P;
 use rustc_ast::{token, Attribute, Inline, Item};
 use rustc_errors::{struct_span_err, DiagnosticBuilder};
 use rustc_parse::new_parser_from_file;
+use rustc_parse::validate_attr;
 use rustc_session::parse::ParseSess;
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Ident};
@@ -168,7 +169,25 @@ fn mod_file_path_from_attr(
     dir_path: &Path,
 ) -> Option<PathBuf> {
     // Extract path string from first `#[path = "path_string"]` attribute.
-    let path_string = sess.first_attr_value_str_by_name(attrs, sym::path)?.as_str();
+    let first_path = attrs.iter().find(|at| at.has_name(sym::path))?;
+    let path_string = match first_path.value_str() {
+        Some(s) => s.as_str(),
+        None => {
+            // This check is here mainly to catch attempting to use a macro,
+            // such as #[path = concat!(...)]. This isn't currently supported
+            // because otherwise the InvocationCollector would need to defer
+            // loading a module until the #[path] attribute was expanded, and
+            // it doesn't support that (and would likely add a bit of
+            // complexity). Usually bad forms are checked in AstValidator (via
+            // `check_builtin_attribute`), but by the time that runs the macro
+            // is expanded, and it doesn't give an error.
+            validate_attr::emit_fatal_malformed_builtin_attribute(
+                &sess.parse_sess,
+                first_path,
+                sym::path,
+            );
+        }
+    };
 
     // On windows, the base path might have the form
     // `\\?\foo\bar` in which case it does not tolerate

Diff for: compiler/rustc_interface/src/passes.rs

@@ -23,7 +23,7 @@ use rustc_middle::middle::cstore::{MetadataLoader, MetadataLoaderDyn};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, GlobalCtxt, ResolverOutputs, TyCtxt};
 use rustc_mir_build as mir_build;
-use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str};
+use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str, validate_attr};
 use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
 use rustc_query_impl::{OnDiskCache, Queries as TcxQueries};
@@ -33,8 +33,8 @@ use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType, PpMod
 use rustc_session::lint;
 use rustc_session::output::{filename_for_input, filename_for_metadata};
 use rustc_session::search_paths::PathKind;
-use rustc_session::Session;
-use rustc_span::symbol::{Ident, Symbol};
+use rustc_session::{Limit, Session};
+use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::FileName;
 use rustc_trait_selection::traits;
 use rustc_typeck as typeck;
@@ -311,8 +311,7 @@ pub fn configure_and_expand(
 
         // Create the config for macro expansion
         let features = sess.features_untracked();
-        let recursion_limit =
-            rustc_middle::middle::limits::get_recursion_limit(&krate.attrs, &sess);
+        let recursion_limit = get_recursion_limit(&krate.attrs, &sess);
         let cfg = rustc_expand::expand::ExpansionConfig {
             features: Some(&features),
             recursion_limit,
@@ -1070,3 +1069,24 @@ pub fn start_codegen<'tcx>(
 
     codegen
 }
+
+fn get_recursion_limit(krate_attrs: &[ast::Attribute], sess: &Session) -> Limit {
+    if let Some(attr) = krate_attrs
+        .iter()
+        .find(|attr| attr.has_name(sym::recursion_limit) && attr.value_str().is_none())
+    {
+        // This is here mainly to check for using a macro, such as
+        // #![recursion_limit = foo!()]. That is not supported since that
+        // would require expanding this while in the middle of expansion,
+        // which needs to know the limit before expanding. Otherwise,
+        // validation would normally be caught in AstValidator (via
+        // `check_builtin_attribute`), but by the time that runs the macro
+        // is expanded, and it doesn't give an error.
+        validate_attr::emit_fatal_malformed_builtin_attribute(
+            &sess.parse_sess,
+            attr,
+            sym::recursion_limit,
+        );
+    }
+    rustc_middle::middle::limits::get_recursion_limit(krate_attrs, sess)
+}

Diff for: compiler/rustc_interface/src/util.rs

@@ -10,6 +10,7 @@ use rustc_errors::registry::Registry;
 use rustc_metadata::dynamic_lib::DynamicLibrary;
 #[cfg(parallel_compiler)]
 use rustc_middle::ty::tls;
+use rustc_parse::validate_attr;
 #[cfg(parallel_compiler)]
 use rustc_query_impl::QueryCtxt;
 use rustc_resolve::{self, Resolver};
@@ -475,7 +476,7 @@ pub fn get_codegen_sysroot(
 }
 
 pub(crate) fn check_attr_crate_type(
-    _sess: &Session,
+    sess: &Session,
     attrs: &[ast::Attribute],
     lint_buffer: &mut LintBuffer,
 ) {
@@ -515,6 +516,19 @@ pub(crate) fn check_attr_crate_type(
                         );
                     }
                 }
+            } else {
+                // This is here mainly to check for using a macro, such as
+                // #![crate_type = foo!()]. That is not supported since the
+                // crate type needs to be known very early in compilation long
+                // before expansion. Otherwise, validation would normally be
+                // caught in AstValidator (via `check_builtin_attribute`), but
+                // by the time that runs the macro is expanded, and it doesn't
+                // give an error.
+                validate_attr::emit_fatal_malformed_builtin_attribute(
+                    &sess.parse_sess,
+                    a,
+                    sym::crate_type,
+                );
             }
         }
     }

Diff for: compiler/rustc_parse/src/validate_attr.rs

@@ -4,7 +4,7 @@ use crate::parse_in;
 
 use rustc_ast::tokenstream::{DelimSpan, TokenTree};
 use rustc_ast::{self as ast, Attribute, MacArgs, MacDelimiter, MetaItem, MetaItemKind};
-use rustc_errors::{Applicability, PResult};
+use rustc_errors::{Applicability, FatalError, PResult};
 use rustc_feature::{AttributeTemplate, BUILTIN_ATTRIBUTE_MAP};
 use rustc_session::lint::builtin::ILL_FORMED_ATTRIBUTE_INPUT;
 use rustc_session::parse::ParseSess;
@@ -162,3 +162,15 @@ fn emit_malformed_attribute(
             .emit();
     }
 }
+
+pub fn emit_fatal_malformed_builtin_attribute(
+    sess: &ParseSess,
+    attr: &Attribute,
+    name: Symbol,
+) -> ! {
+    let template = BUILTIN_ATTRIBUTE_MAP.get(&name).expect("builtin attr defined").2;
+    emit_malformed_attribute(sess, attr, name, template);
+    // This is fatal, otherwise it will likely cause a cascade of other errors
+    // (and an error here is expected to be very rare).
+    FatalError.raise()
+}

Diff for: src/test/ui/invalid/invalid-crate-type-macro.rs

@@ -0,0 +1,7 @@
+#![crate_type = foo!()] //~ ERROR malformed `crate_type` attribute
+
+macro_rules! foo {
+    () => {"rlib"};
+}
+
+fn main() {}

Diff for: src/test/ui/invalid/invalid-crate-type-macro.stderr

@@ -0,0 +1,8 @@
+error: malformed `crate_type` attribute input
+  --> $DIR/invalid-crate-type-macro.rs:1:1
+   |
+LL | #![crate_type = foo!()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#![crate_type = "bin|lib|..."]`
+
+error: aborting due to previous error
+

Diff for: src/test/ui/modules/path-invalid-form.rs

@@ -0,0 +1,4 @@
+#[path = 123]  //~ ERROR malformed `path` attribute
+mod foo;
+
+fn main() {}

Diff for: src/test/ui/modules/path-invalid-form.stderr

@@ -0,0 +1,8 @@
+error: malformed `path` attribute input
+  --> $DIR/path-invalid-form.rs:1:1
+   |
+LL | #[path = 123]
+   | ^^^^^^^^^^^^^ help: must be of the form: `#[path = "file"]`
+
+error: aborting due to previous error
+

Diff for: src/test/ui/modules/path-macro.rs

@@ -0,0 +1,8 @@
+macro_rules! foo {
+    () => {"bar.rs"};
+}
+
+#[path = foo!()] //~ ERROR malformed `path` attribute
+mod abc;
+
+fn main() {}

Diff for: src/test/ui/modules/path-macro.stderr

@@ -0,0 +1,8 @@
+error: malformed `path` attribute input
+  --> $DIR/path-macro.rs:5:1
+   |
+LL | #[path = foo!()]
+   | ^^^^^^^^^^^^^^^^ help: must be of the form: `#[path = "file"]`
+
+error: aborting due to previous error
+

Diff for: src/test/ui/recursion_limit/invalid_digit_type.rs

@@ -0,0 +1,3 @@
+#![recursion_limit = 123] //~ ERROR malformed `recursion_limit` attribute
+
+fn main() {}

Diff for: src/test/ui/recursion_limit/invalid_digit_type.stderr

@@ -0,0 +1,8 @@
+error: malformed `recursion_limit` attribute input
+  --> $DIR/invalid_digit_type.rs:1:1
+   |
+LL | #![recursion_limit = 123]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#![recursion_limit = "N"]`
+
+error: aborting due to previous error
+

Diff for: src/test/ui/recursion_limit/invalid_macro.rs

@@ -0,0 +1,7 @@
+#![recursion_limit = foo!()] //~ ERROR malformed `recursion_limit` attribute
+
+macro_rules! foo {
+    () => {"128"};
+}
+
+fn main() {}

Diff for: src/test/ui/recursion_limit/invalid_macro.stderr

@@ -0,0 +1,8 @@
+error: malformed `recursion_limit` attribute input
+  --> $DIR/invalid_macro.rs:1:1
+   |
+LL | #![recursion_limit = foo!()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#![recursion_limit = "N"]`
+
+error: aborting due to previous error
+