compiletest: add enable-by-default check-cfg

src/tools/compiletest/src/runtest.rs

@@ -1028,12 +1028,31 @@ fn compare_source(&self, expected: &str, actual: &str) {
     }
 
     fn set_revision_flags(&self, cmd: &mut Command) {
+        // Normalize revisions to be lowercase and replace `-`s with `_`s.
+        // Otherwise the `--cfg` flag is not valid.
+        let normalize_revision = |revision: &str| revision.to_lowercase().replace("-", "_");
+
         if let Some(revision) = self.revision {
-            // Normalize revisions to be lowercase and replace `-`s with `_`s.
-            // Otherwise the `--cfg` flag is not valid.
-            let normalized_revision = revision.to_lowercase().replace("-", "_");
+            let normalized_revision = normalize_revision(revision);
             cmd.args(&["--cfg", &normalized_revision]);
         }
+
+        if !self.props.no_auto_check_cfg {
+            let mut check_cfg = String::with_capacity(25);
+
+            // Generate `cfg(FALSE, REV1, ..., REVN)` (for all possible revisions)
+            //
+            // For compatibility reason we consider the `FALSE` cfg to be expected
+            // since it is extensively used in the testsuite.
+            check_cfg.push_str("cfg(FALSE");
+            for revision in &self.props.revisions {
+                check_cfg.push_str(",");
+                check_cfg.push_str(&normalize_revision(&revision));
+            }
+            check_cfg.push_str(")");
+
+            cmd.args(&["--check-cfg", &check_cfg]);
+        }
     }
 
     fn typecheck_source(&self, src: String) -> ProcRes {

tests/rustdoc-ui/argfile/commandline-argfile.rs

@@ -1,7 +1,8 @@
 // Check to see if we can get parameters from an @argsfile file
 //
 //@ check-pass
-//@ compile-flags: --cfg cmdline_set @{{src-base}}/argfile/commandline-argfile.args
+//@ compile-flags: --cfg cmdline_set --check-cfg=cfg(cmdline_set,unbroken)
+//@ compile-flags: @{{src-base}}/argfile/commandline-argfile.args
 
 #[cfg(not(cmdline_set))]
 compile_error!("cmdline_set not set");
@@ -9,5 +10,4 @@
 #[cfg(not(unbroken))]
 compile_error!("unbroken not set");
 
-fn main() {
-}
+fn main() {}

tests/ui/argfile/commandline-argfile.rs

@@ -1,7 +1,8 @@
 // Check to see if we can get parameters from an @argsfile file
 //
 //@ build-pass
-//@ compile-flags: --cfg cmdline_set @{{src-base}}/argfile/commandline-argfile.args
+//@ compile-flags: --cfg cmdline_set --check-cfg=cfg(cmdline_set,unbroken)
+//@ compile-flags: @{{src-base}}/argfile/commandline-argfile.args
 
 #[cfg(not(cmdline_set))]
 compile_error!("cmdline_set not set");
@@ -9,5 +10,4 @@
 #[cfg(not(unbroken))]
 compile_error!("unbroken not set");
 
-fn main() {
-}
+fn main() {}

tests/ui/cfg/cfg-in-crate-1.rs

@@ -1,5 +1,6 @@
 //@ run-pass
-//@ compile-flags: --cfg bar -D warnings
+//@ compile-flags: --cfg bar --check-cfg=cfg(bar) -D warnings
+
 #![cfg(bar)]
 
 fn main() {}

tests/ui/cfg/cfg-macros-foo.rs

@@ -1,5 +1,5 @@
 //@ run-pass
-//@ compile-flags: --cfg foo
+//@ compile-flags: --cfg foo --check-cfg=cfg(foo)
 
 // check that cfg correctly chooses between the macro impls (see also
 // cfg-macros-notfoo.rs)

tests/ui/cfg/cfg-path-error.rs

@@ -1,5 +1,7 @@
 //@ check-fail
 
+#![allow(unexpected_cfgs)] // invalid cfgs
+
 #[cfg(any(foo, foo::bar))]
 //~^ERROR `cfg` predicate key must be an identifier
 fn foo1() {}

tests/ui/cfg/cfg-path-error.stderr

@@ -1,23 +1,23 @@
 error: `cfg` predicate key must be an identifier
-  --> $DIR/cfg-path-error.rs:3:16
+  --> $DIR/cfg-path-error.rs:5:16
    |
 LL | #[cfg(any(foo, foo::bar))]
    |                ^^^^^^^^
 
 error: `cfg` predicate key must be an identifier
-  --> $DIR/cfg-path-error.rs:7:11
+  --> $DIR/cfg-path-error.rs:9:11
    |
 LL | #[cfg(any(foo::bar, foo))]
    |           ^^^^^^^^
 
 error: `cfg` predicate key must be an identifier
-  --> $DIR/cfg-path-error.rs:11:16
+  --> $DIR/cfg-path-error.rs:13:16
    |
 LL | #[cfg(all(foo, foo::bar))]
    |                ^^^^^^^^
 
 error: `cfg` predicate key must be an identifier
-  --> $DIR/cfg-path-error.rs:15:11
+  --> $DIR/cfg-path-error.rs:17:11
    |
 LL | #[cfg(all(foo::bar, foo))]
    |           ^^^^^^^^

tests/ui/cfg/cfg_attr.rs

@@ -1,6 +1,8 @@
 //@ run-pass
 //@ compile-flags:--cfg set1 --cfg set2
-#![allow(dead_code)]
+
+#![allow(dead_code, unexpected_cfgs)]
+
 use std::fmt::Debug;
 
 struct NotDebugable;

tests/ui/cfg/cfgs-on-items.rs

@@ -1,8 +1,7 @@
 //@ run-pass
-//@ compile-flags: --cfg fooA --cfg fooB
+//@ compile-flags: --cfg fooA --cfg fooB --check-cfg=cfg(fooA,fooB,fooC,bar)
 
 // fooA AND !bar
-
 #[cfg(all(fooA, not(bar)))]
 fn foo1() -> isize { 1 }
 

tests/ui/cfg/diagnostics-not-a-def.rs

@@ -1,4 +1,7 @@
+#![feature(lint_reasons)]
+
 pub mod inner {
+    #[expect(unexpected_cfgs)]
     pub fn i_am_here() {
         #[cfg(feature = "another one that doesn't exist")]
         loop {}

tests/ui/cfg/diagnostics-not-a-def.stderr

@@ -1,5 +1,5 @@
 error[E0425]: cannot find function `i_am_not` in module `inner`
-  --> $DIR/diagnostics-not-a-def.rs:11:12
+  --> $DIR/diagnostics-not-a-def.rs:14:12
    |
 LL |     inner::i_am_not();
    |            ^^^^^^^^ not found in `inner`

tests/ui/cfg/diagnostics-same-crate.rs

@@ -1,3 +1,5 @@
+#![allow(unexpected_cfgs)] // since we want to recognize them as unexpected
+
 pub mod inner {
     #[cfg(FALSE)]
     pub fn uwu() {}

tests/ui/cfg/diagnostics-same-crate.stderr

@@ -1,72 +1,72 @@
 error[E0432]: unresolved import `super::inner::doesnt_exist`
-  --> $DIR/diagnostics-same-crate.rs:28:9
+  --> $DIR/diagnostics-same-crate.rs:30:9
    |
 LL |     use super::inner::doesnt_exist;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ no `doesnt_exist` in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:7:13
+  --> $DIR/diagnostics-same-crate.rs:9:13
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
 
 error[E0432]: unresolved import `super::inner::doesnt_exist`
-  --> $DIR/diagnostics-same-crate.rs:31:23
+  --> $DIR/diagnostics-same-crate.rs:33:23
    |
 LL |     use super::inner::doesnt_exist::hi;
    |                       ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:7:13
+  --> $DIR/diagnostics-same-crate.rs:9:13
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
 
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-same-crate.rs:50:12
+  --> $DIR/diagnostics-same-crate.rs:52:12
    |
 LL |     inner::doesnt_exist::hello();
    |            ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:7:13
+  --> $DIR/diagnostics-same-crate.rs:9:13
    |
 LL |     pub mod doesnt_exist {
    |             ^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
-  --> $DIR/diagnostics-same-crate.rs:45:12
+  --> $DIR/diagnostics-same-crate.rs:47:12
    |
 LL |     inner::uwu();
    |            ^^^ not found in `inner`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:3:12
+  --> $DIR/diagnostics-same-crate.rs:5:12
    |
 LL |     pub fn uwu() {}
    |            ^^^
 
 error[E0425]: cannot find function `meow` in module `inner::right`
-  --> $DIR/diagnostics-same-crate.rs:54:19
+  --> $DIR/diagnostics-same-crate.rs:56:19
    |
 LL |     inner::right::meow();
    |                   ^^^^ not found in `inner::right`
    |
 note: found an item that was configured out
-  --> $DIR/diagnostics-same-crate.rs:22:16
+  --> $DIR/diagnostics-same-crate.rs:24:16
    |
 LL |         pub fn meow() {}
    |                ^^^^
    = note: the item is gated behind the `what-a-cool-feature` feature
 
 error[E0425]: cannot find function `uwu` in this scope
-  --> $DIR/diagnostics-same-crate.rs:41:5
+  --> $DIR/diagnostics-same-crate.rs:43:5
    |
 LL |     uwu();
    |     ^^^ not found in this scope
 
 error[E0425]: cannot find function `vanished` in this scope
-  --> $DIR/diagnostics-same-crate.rs:61:5
+  --> $DIR/diagnostics-same-crate.rs:63:5
    |
 LL |     vanished();
    |     ^^^^^^^^ not found in this scope

tests/ui/cfg/expanded-cfg.rs

@@ -1,5 +1,7 @@
 //@ check-pass
 
+#![allow(unexpected_cfgs)] // since we different cfgs
+
 macro_rules! mac {
     {} => {
         #[cfg(attr)]

tests/ui/cfg/future-compat-crate-attributes-using-cfg_attr.rs

@@ -1,5 +1,5 @@
 //@ check-fail
-//@ compile-flags:--cfg foo
+//@ compile-flags:--cfg foo --check-cfg=cfg(foo)
 
 #![cfg_attr(foo, crate_type="bin")]
 //~^ERROR `crate_type` within

tests/ui/conditional-compilation/cfg-attr-cfg-2.rs

@@ -1,6 +1,5 @@
-//
 //@ error-pattern: `main` function not found
-//@ compile-flags: --cfg foo
+//@ compile-flags: --cfg foo --check-cfg=cfg(foo,bar)
 
 // main is conditionally compiled, but the conditional compilation
 // is conditional too!

tests/ui/conditional-compilation/cfg-attr-cfg-2.stderr

@@ -1,5 +1,5 @@
 error[E0601]: `main` function not found in crate `cfg_attr_cfg_2`
-  --> $DIR/cfg-attr-cfg-2.rs:9:14
+  --> $DIR/cfg-attr-cfg-2.rs:8:14
    |
 LL | fn main() { }
    |              ^ consider adding a `main` function to `$DIR/cfg-attr-cfg-2.rs`

tests/ui/conditional-compilation/cfg-attr-crate-2.rs

@@ -1,6 +1,6 @@
 // https://github.com/rust-lang/rust/issues/21833#issuecomment-72353044
 
-//@ compile-flags: --cfg broken
+//@ compile-flags: --cfg broken --check-cfg=cfg(broken)
 
 #![crate_type = "lib"]
 #![cfg_attr(broken, no_core)] //~ ERROR the `#[no_core]` attribute is an experimental feature

tests/ui/conditional-compilation/cfg-attr-multi-invalid-1.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: --cfg broken
+//@ compile-flags: --cfg broken --check-cfg=cfg(broken)
 
 #![crate_type = "lib"]
 #![cfg_attr(broken, no_core, no_std)]

tests/ui/conditional-compilation/cfg-attr-multi-invalid-2.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: --cfg broken
+//@ compile-flags: --cfg broken --check-cfg=cfg(broken)
 
 #![crate_type = "lib"]
 #![cfg_attr(broken, no_std, no_core)]

tests/ui/conditional-compilation/cfg-generic-params.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:--cfg yes
+//@ compile-flags:--cfg yes --check-cfg=cfg(yes,no)
 
 fn f_lt<#[cfg(yes)] 'a: 'a, #[cfg(FALSE)] T>() {}
 fn f_ty<#[cfg(FALSE)] 'a: 'a, #[cfg(yes)] T>() {}

tests/ui/conditional-compilation/test-cfg.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: --cfg foo
+//@ compile-flags: --cfg foo --check-cfg=cfg(foo,bar)
 
 #[cfg(all(foo, bar))] // foo AND bar
 fn foo() {}

tests/ui/imports/extern-prelude-extern-crate-cfg.rs

@@ -1,5 +1,5 @@
 //@ build-pass (FIXME(62277): could be check-pass?)
-//@ compile-flags:--cfg my_feature
+//@ compile-flags:--cfg my_feature --check-cfg=cfg(my_feature)
 
 #![no_std]
 

tests/ui/macros/macro-comma-support-rpass.rs

@@ -51,6 +51,7 @@ fn assert_ne() {
 }
 
 #[test]
+#[allow(unexpected_cfgs)]
 fn cfg() {
     let _ = cfg!(pants);
     let _ = cfg!(pants,);

tests/ui/macros/macro-meta-items.rs

@@ -1,6 +1,7 @@
 //@ run-pass
+//@ compile-flags: --cfg foo --check-cfg=cfg(foo)
+
 #![allow(dead_code)]
-//@ compile-flags: --cfg foo
 
 macro_rules! compiles_fine {
     ($at:meta) => {

tests/ui/macros/macro-with-attrs1.rs

@@ -1,5 +1,5 @@
 //@ run-pass
-//@ compile-flags: --cfg foo
+//@ compile-flags: --cfg foo --check-cfg=cfg(foo)
 
 
 #[cfg(foo)]

tests/ui/macros/syntax-extension-cfg.rs

@@ -1,6 +1,6 @@
 //@ run-pass
 //@ compile-flags: --cfg foo --cfg qux="foo"
-
+//@ compile-flags: --check-cfg=cfg(foo) --check-cfg=cfg(qux,values("foo"))
 
 pub fn main() {
     // check

tests/ui/methods/method-lookup-order.rs

@@ -18,6 +18,9 @@
 
 //@ revisions: b00001 b00010 b00011 b00100 b00101 b00110 b00111 b01000 b01001 b01100 b01101 b10000 b10001 b10010 b10011 b10101 b10111 b11000 b11001 b11101
 
+//@ compile-flags: --check-cfg=cfg(inherent_mut,bar_for_foo,mutbar_for_foo)
+//@ compile-flags: --check-cfg=cfg(valbar_for_et_foo,valbar_for_etmut_foo)
+
 //@[b00001]compile-flags:  --cfg inherent_mut
 //@[b00010]compile-flags:                     --cfg bar_for_foo
 //@[b00011]compile-flags:  --cfg inherent_mut --cfg bar_for_foo

tests/ui/parser/attribute/attr-unquoted-ident.fixed

@@ -1,6 +1,8 @@
 //@ compile-flags: -Zdeduplicate-diagnostics=yes
 //@ run-rustfix
 
+#![allow(unexpected_cfgs)]
+
 fn main() {
     #[cfg(key="foo")]
     //~^ ERROR expected unsuffixed literal, found `foo`

tests/ui/parser/attribute/attr-unquoted-ident.rs

@@ -1,6 +1,8 @@
 //@ compile-flags: -Zdeduplicate-diagnostics=yes
 //@ run-rustfix
 
+#![allow(unexpected_cfgs)]
+
 fn main() {
     #[cfg(key=foo)]
     //~^ ERROR expected unsuffixed literal, found `foo`

tests/ui/parser/attribute/attr-unquoted-ident.stderr

@@ -1,5 +1,5 @@
 error: expected unsuffixed literal, found `foo`
-  --> $DIR/attr-unquoted-ident.rs:5:15
+  --> $DIR/attr-unquoted-ident.rs:7:15
    |
 LL |     #[cfg(key=foo)]
    |               ^^^
@@ -10,7 +10,7 @@ LL |     #[cfg(key="foo")]
    |               +   +
 
 error: expected unsuffixed literal, found `foo`
-  --> $DIR/attr-unquoted-ident.rs:11:15
+  --> $DIR/attr-unquoted-ident.rs:13:15
    |
 LL |     #[cfg(key=foo bar baz)]
    |               ^^^

tests/ui/regions/regions-refcell.rs

@@ -3,6 +3,7 @@
 // attempting to bootstrap librustc with new destructor lifetime
 // semantics.
 
+#![allow(unexpected_cfgs)] // for the cfg-as-descriptions
 
 use std::collections::HashMap;
 use std::cell::RefCell;

tests/ui/resolve/suggest-import-without-clobbering-attrs.fixed

@@ -1,8 +1,8 @@
 //@ run-rustfix
-//@ compile-flags: --cfg=whatever -Aunused
+//@ compile-flags: -Aunused
 
 use y::z;
-#[cfg(whatever)]
+#[cfg(all())]
 use y::Whatever;
 
 mod y {

tests/ui/resolve/suggest-import-without-clobbering-attrs.rs

@@ -1,7 +1,7 @@
 //@ run-rustfix
-//@ compile-flags: --cfg=whatever -Aunused
+//@ compile-flags: -Aunused
 
-#[cfg(whatever)]
+#[cfg(all())]
 use y::Whatever;
 
 mod y {

tests/ui/rfcs/rfc-2565-param-attrs/param-attrs-allowed.rs

@@ -1,5 +1,5 @@
 //@ check-pass
-//@ compile-flags: --cfg something
+//@ compile-flags: --cfg something --check-cfg=cfg(nothing,something)
 
 #![deny(unused_mut)]
 

tests/ui/rfcs/rfc-2565-param-attrs/param-attrs-cfg.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: --cfg something
+//@ compile-flags: --cfg something --check-cfg=cfg(nothing,something)
 //@ edition:2018
 
 #![feature(async_closure)]

tests/ui/rust-2018/issue-54400-unused-extern-crate-attr-span.fixed

@@ -4,7 +4,7 @@
 //@ edition:2018
 
 #![deny(rust_2018_idioms)]
-#![allow(dead_code)]
+#![allow(dead_code, unexpected_cfgs)]
 
 // The suggestion span should include the attribute.
 

tests/ui/rust-2018/issue-54400-unused-extern-crate-attr-span.rs

@@ -4,7 +4,7 @@
 //@ edition:2018
 
 #![deny(rust_2018_idioms)]
-#![allow(dead_code)]
+#![allow(dead_code, unexpected_cfgs)]
 
 // The suggestion span should include the attribute.
 

tests/ui/shell-argfiles/shell-argfiles-via-argfile.rs

@@ -1,6 +1,7 @@
 // Check to see if we can get parameters from an @argsfile file
 //
 //@ build-pass
+//@ no-auto-check-cfg
 //@ compile-flags: @{{src-base}}/shell-argfiles/shell-argfiles-via-argfile.args @shell:{{src-base}}/shell-argfiles/shell-argfiles-via-argfile-shell.args
 
 #[cfg(not(shell_args_set))]

tests/ui/shell-argfiles/shell-argfiles.args

@@ -1,3 +1,4 @@
 --cfg unquoted_set
 '--cfg' 'single_quoted_set'
 "--cfg" "double_quoted_set"
+--check-cfg 'cfg(cmdline_set, unquoted_set, single_quoted_set, double_quoted_set)'

tests/ui/sse2.rs

@@ -2,6 +2,7 @@
 
 #![allow(stable_features)]
 #![feature(cfg_target_feature)]
+#![feature(lint_reasons)]
 
 use std::env;
 
@@ -20,6 +21,7 @@ fn main() {
                 "SSE2 was not detected as available on an x86 platform");
     }
     // check a negative case too -- certainly not enabled by default
-    assert!(cfg!(not(target_feature = "ferris_wheel")),
-            "🎡 shouldn't be detected as available by default on any platform");
+    #[expect(unexpected_cfgs)]
+    { assert!(cfg!(not(target_feature = "ferris_wheel")),
+            "🎡 shouldn't be detected as available by default on any platform") };
 }

tests/ui/target-feature/no-llvm-leaks.rs

@@ -6,7 +6,7 @@
 //@ build-pass
 #![no_core]
 #![crate_type = "rlib"]
-#![feature(intrinsics, rustc_attrs, no_core, lang_items, staged_api)]
+#![feature(intrinsics, rustc_attrs, no_core, lang_items, staged_api, lint_reasons)]
 #![stable(feature = "test", since = "1.0.0")]
 
 // Supporting minimal rust core code
@@ -43,22 +43,30 @@ macro_rules! assert {
 
 #[cfg(target_arch = "aarch64")]
 fn check_aarch64() {
-    // This checks that the rustc feature name is used, not the LLVM feature.
+    // These checks that the rustc feature name is used, not the LLVM feature.
+
     assert!(cfg!(target_feature = "neon"));
-    assert!(cfg!(not(target_feature = "fp-armv8")));
+    // #[expect(unexpected_cfgs)] except that 32-bit arm actually use fp-armv8
+    { assert!(cfg!(not(target_feature = "fp-armv8"))); }
+
     assert!(cfg!(target_feature = "fhm"));
-    assert!(cfg!(not(target_feature = "fp16fml")));
+    #[expect(unexpected_cfgs)]
+    { assert!(cfg!(not(target_feature = "fp16fml"))); }
+
     assert!(cfg!(target_feature = "fp16"));
-    assert!(cfg!(not(target_feature = "fullfp16")));
+    #[expect(unexpected_cfgs)]
+    { assert!(cfg!(not(target_feature = "fullfp16"))); }
 }
 
 #[cfg(target_arch = "x86_64")]
 fn check_x86_64() {
     // This checks that the rustc feature name is used, not the LLVM feature.
     assert!(cfg!(target_feature = "rdrand"));
-    assert!(cfg!(not(target_feature = "rdrnd")));
+    #[expect(unexpected_cfgs)]
+    { assert!(cfg!(not(target_feature = "rdrnd"))); }
 
     // Likewise: We enable LLVM's crc32 feature with SSE4.2, but Rust says it's just SSE4.2
     assert!(cfg!(target_feature = "sse4.2"));
-    assert!(cfg!(not(target_feature = "crc32")));
+    #[expect(unexpected_cfgs)]
+    { assert!(cfg!(not(target_feature = "crc32"))); }
 }