diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs index 690f80f6876..bcfa5313bde 100644 --- a/compiler/rustc_expand/src/config.rs +++ b/compiler/rustc_expand/src/config.rs @@ -197,9 +197,11 @@ pub fn pre_configure_attrs(sess: &Session, attrs: &[Attribute]) -> ast::AttrVec config_tokens: false, lint_node_id: ast::CRATE_NODE_ID, }; - let attrs: ast::AttrVec = - attrs.iter().flat_map(|attr| strip_unconfigured.process_cfg_attr(attr)).collect(); - if strip_unconfigured.in_cfg(&attrs) { attrs } else { ast::AttrVec::new() } + attrs + .iter() + .flat_map(|attr| strip_unconfigured.process_cfg_attr(attr)) + .take_while(|attr| !is_cfg(attr) || strip_unconfigured.cfg_true(attr).0) + .collect() } #[macro_export] diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs index dd8863df195..9850723a857 100644 --- a/compiler/rustc_expand/src/expand.rs +++ b/compiler/rustc_expand/src/expand.rs @@ -1039,7 +1039,12 @@ fn wrap_flat_map_node_noop_flat_map( ) -> Result { Ok(noop_flat_map(node, collector)) } - fn expand_cfg_false(&mut self, collector: &mut InvocationCollector<'_, '_>, span: Span) { + fn expand_cfg_false( + &mut self, + collector: &mut InvocationCollector<'_, '_>, + _pos: usize, + span: Span, + ) { collector.cx.emit_err(RemoveNodeNotSupported { span, descr: Self::descr() }); } @@ -1409,8 +1414,15 @@ fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy { fn noop_visit(&mut self, visitor: &mut V) { noop_visit_crate(self, visitor) } - fn expand_cfg_false(&mut self, collector: &mut InvocationCollector<'_, '_>, _span: Span) { - self.attrs.clear(); + fn expand_cfg_false( + &mut self, + collector: &mut InvocationCollector<'_, '_>, + pos: usize, + _span: Span, + ) { + // Attributes above `cfg(FALSE)` are left in place, because we may want to configure + // some global crate properties even on fully unconfigured crates. + self.attrs.truncate(pos); // Standard prelude imports are left in the crate for backward compatibility. self.items.truncate(collector.cx.num_standard_library_imports); } @@ -1804,7 +1816,7 @@ fn visit_node + DummyAstNode>( continue; } - node.expand_cfg_false(self, span); + node.expand_cfg_false(self, pos, span); continue; } sym::cfg_attr => { diff --git a/tests/ui/cfg/auxiliary/cfg_false_lib.rs b/tests/ui/cfg/auxiliary/cfg_false_lib.rs index 3c011d72b02..6c2dbb44d2a 100644 --- a/tests/ui/cfg/auxiliary/cfg_false_lib.rs +++ b/tests/ui/cfg/auxiliary/cfg_false_lib.rs @@ -1,6 +1,4 @@ -// It is unclear whether a fully unconfigured crate should link to standard library, -// or what its `no_std`/`no_core`/`compiler_builtins` status, more precisely. -// Currently the usual standard library prelude is added to such crates, -// and therefore they link to libstd. +// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(FALSE)`. +// This crate has no such attribute, therefore this crate does link to libstd. #![cfg(FALSE)] diff --git a/tests/ui/cfg/auxiliary/cfg_false_lib_no_std_after.rs b/tests/ui/cfg/auxiliary/cfg_false_lib_no_std_after.rs new file mode 100644 index 00000000000..3cfa6c510d0 --- /dev/null +++ b/tests/ui/cfg/auxiliary/cfg_false_lib_no_std_after.rs @@ -0,0 +1,5 @@ +// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(FALSE)`. +// Therefore this crate does link to libstd. + +#![cfg(FALSE)] +#![no_std] diff --git a/tests/ui/cfg/auxiliary/cfg_false_lib_no_std_before.rs b/tests/ui/cfg/auxiliary/cfg_false_lib_no_std_before.rs new file mode 100644 index 00000000000..8e89545b8f4 --- /dev/null +++ b/tests/ui/cfg/auxiliary/cfg_false_lib_no_std_before.rs @@ -0,0 +1,8 @@ +// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(FALSE)`. +// Therefore this crate doesn't link to libstd. + +// no-prefer-dynamic + +#![no_std] +#![crate_type = "lib"] +#![cfg(FALSE)] diff --git a/tests/ui/cfg/cfg-false-feature.rs b/tests/ui/cfg/cfg-false-feature.rs index 21ea3ec79b4..84c231562f1 100644 --- a/tests/ui/cfg/cfg-false-feature.rs +++ b/tests/ui/cfg/cfg-false-feature.rs @@ -1,5 +1,4 @@ -// It is unclear which features should be in effect in a fully unconfigured crate (issue #104633). -// Currently none on the features are in effect, so we get the feature gates reported. +// Features above `cfg(FALSE)` are in effect in a fully unconfigured crate (issue #104633). // check-pass // compile-flags: --crate-type lib @@ -8,8 +7,7 @@ #![cfg(FALSE)] #![feature(box_syntax)] -macro mac() {} //~ WARN `macro` is experimental - //~| WARN unstable syntax can change at any point in the future +macro mac() {} // OK trait A = Clone; //~ WARN trait aliases are experimental //~| WARN unstable syntax can change at any point in the future diff --git a/tests/ui/cfg/cfg-false-feature.stderr b/tests/ui/cfg/cfg-false-feature.stderr index 14673fbdb14..34093036205 100644 --- a/tests/ui/cfg/cfg-false-feature.stderr +++ b/tests/ui/cfg/cfg-false-feature.stderr @@ -1,5 +1,5 @@ warning: trait aliases are experimental - --> $DIR/cfg-false-feature.rs:14:1 + --> $DIR/cfg-false-feature.rs:12:1 | LL | trait A = Clone; | ^^^^^^^^^^^^^^^^ @@ -9,19 +9,8 @@ LL | trait A = Clone; = warning: unstable syntax can change at any point in the future, causing a hard error! = note: for more information, see issue #65860 -warning: `macro` is experimental - --> $DIR/cfg-false-feature.rs:11:1 - | -LL | macro mac() {} - | ^^^^^^^^^^^^^^ - | - = note: see issue #39412 for more information - = help: add `#![feature(decl_macro)]` to the crate attributes to enable - = warning: unstable syntax can change at any point in the future, causing a hard error! - = note: for more information, see issue #65860 - warning: box pattern syntax is experimental - --> $DIR/cfg-false-feature.rs:18:9 + --> $DIR/cfg-false-feature.rs:16:9 | LL | let box _ = Box::new(0); | ^^^^^ @@ -31,5 +20,5 @@ LL | let box _ = Box::new(0); = warning: unstable syntax can change at any point in the future, causing a hard error! = note: for more information, see issue #65860 -warning: 3 warnings emitted +warning: 2 warnings emitted diff --git a/tests/ui/cfg/cfg_false_no_std-1.rs b/tests/ui/cfg/cfg_false_no_std-1.rs new file mode 100644 index 00000000000..bcb49e51353 --- /dev/null +++ b/tests/ui/cfg/cfg_false_no_std-1.rs @@ -0,0 +1,10 @@ +// No error, panic handler is supplied by libstd linked though the empty library. + +// check-pass +// aux-build: cfg_false_lib_no_std_after.rs + +#![no_std] + +extern crate cfg_false_lib_no_std_after as _; + +fn main() {} diff --git a/tests/ui/cfg/cfg_false_no_std-2.rs b/tests/ui/cfg/cfg_false_no_std-2.rs new file mode 100644 index 00000000000..0a2bfd5f68b --- /dev/null +++ b/tests/ui/cfg/cfg_false_no_std-2.rs @@ -0,0 +1,11 @@ +// Error, the linked empty library is `no_std` and doesn't provide a panic handler. + +// dont-check-compiler-stderr +// error-pattern: `#[panic_handler]` function required, but not found +// aux-build: cfg_false_lib_no_std_before.rs + +#![no_std] + +extern crate cfg_false_lib_no_std_before as _; + +fn main() {} diff --git a/tests/ui/cfg/cfg_false_no_std.rs b/tests/ui/cfg/cfg_false_no_std.rs index 319ea078187..4fa831715ed 100644 --- a/tests/ui/cfg/cfg_false_no_std.rs +++ b/tests/ui/cfg/cfg_false_no_std.rs @@ -1,5 +1,4 @@ -// Currently no error because the panic handler is supplied by libstd linked though the empty -// library, but the desirable behavior is unclear (see comments in cfg_false_lib.rs). +// No error, panic handler is supplied by libstd linked though the empty library. // check-pass // aux-build: cfg_false_lib.rs