Auto merge of #53893 - petrochenkov:cfgexpr, r=pnkfelix

Validate syntax of `cfg` attributes

Fixes https://github.com/rust-lang/rust/issues/53298

src/test/ui/cfg-arg-invalid-1.rs

@@ -0,0 +1,3 @@
+// compile-flags: --cfg a(b=c)
+// error-pattern: invalid `--cfg` argument: `a(b=c)` (expected `key` or `key="value"`)
+fn main() {}

src/test/ui/cfg-arg-invalid-2.rs

@@ -0,0 +1,3 @@
+// compile-flags: --cfg a{b}
+// error-pattern: invalid `--cfg` argument: `a{b}` (expected `key` or `key="value"`)
+fn main() {}

src/test/ui/cfg-arg-invalid-3.rs

@@ -0,0 +1,3 @@
+// compile-flags: --cfg a::b
+// error-pattern: invalid `--cfg` argument: `a::b` (argument key must be an identifier)
+fn main() {}

src/test/ui/cfg-arg-invalid-4.rs

@@ -0,0 +1,3 @@
+// compile-flags: --cfg a(b)
+// error-pattern: invalid `--cfg` argument: `a(b)` (expected `key` or `key="value"`)
+fn main() {}

src/test/ui/cfg-arg-invalid-5.rs

@@ -0,0 +1,3 @@
+// compile-flags: --cfg a=10
+// error-pattern: invalid `--cfg` argument: `a=10` (argument value must be a string)
+fn main() {}

src/test/ui/cfg-arg-invalid.rs

@@ -1,13 +0,0 @@
-// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// compile-flags: --cfg a{b}
-// error-pattern: invalid --cfg argument: a{b}
-fn main() {}

src/test/ui/cfg-attr-syntax-validation.rs

@@ -0,0 +1,32 @@
+#[cfg] //~ ERROR `cfg` is not followed by parentheses
+struct S1;
+
+#[cfg = 10] //~ ERROR `cfg` is not followed by parentheses
+struct S2;
+
+#[cfg()] //~ ERROR `cfg` predicate is not specified
+struct S3;
+
+#[cfg(a, b)] //~ ERROR multiple `cfg` predicates are specified
+struct S4;
+
+#[cfg("str")] //~ ERROR `cfg` predicate key cannot be a literal
+struct S5;
+
+#[cfg(a::b)] //~ ERROR `cfg` predicate key must be an identifier
+struct S6;
+
+#[cfg(a())] //~ ERROR invalid predicate `a`
+struct S7;
+
+#[cfg(a = 10)] //~ ERROR literal in `cfg` predicate value must be a string
+struct S8;
+
+macro_rules! generate_s9 {
+    ($expr: expr) => {
+        #[cfg(feature = $expr)] //~ ERROR `cfg` is not a well-formed meta-item
+        struct S9;
+    }
+}
+
+generate_s9!(concat!("nonexistent"));

src/test/ui/cfg-attr-syntax-validation.stderr

@@ -0,0 +1,60 @@
+error: `cfg` is not followed by parentheses
+  --> $DIR/cfg-attr-syntax-validation.rs:1:1
+   |
+LL | #[cfg] //~ ERROR `cfg` is not followed by parentheses
+   | ^^^^^^ help: expected syntax is: `cfg(/* predicate */)`
+
+error: `cfg` is not followed by parentheses
+  --> $DIR/cfg-attr-syntax-validation.rs:4:1
+   |
+LL | #[cfg = 10] //~ ERROR `cfg` is not followed by parentheses
+   | ^^^^^^^^^^^ help: expected syntax is: `cfg(/* predicate */)`
+
+error: `cfg` predicate is not specified
+  --> $DIR/cfg-attr-syntax-validation.rs:7:1
+   |
+LL | #[cfg()] //~ ERROR `cfg` predicate is not specified
+   | ^^^^^^^^
+
+error: multiple `cfg` predicates are specified
+  --> $DIR/cfg-attr-syntax-validation.rs:10:10
+   |
+LL | #[cfg(a, b)] //~ ERROR multiple `cfg` predicates are specified
+   |          ^
+
+error: `cfg` predicate key cannot be a literal
+  --> $DIR/cfg-attr-syntax-validation.rs:13:7
+   |
+LL | #[cfg("str")] //~ ERROR `cfg` predicate key cannot be a literal
+   |       ^^^^^
+
+error: `cfg` predicate key must be an identifier
+  --> $DIR/cfg-attr-syntax-validation.rs:16:7
+   |
+LL | #[cfg(a::b)] //~ ERROR `cfg` predicate key must be an identifier
+   |       ^^^^
+
+error[E0537]: invalid predicate `a`
+  --> $DIR/cfg-attr-syntax-validation.rs:19:7
+   |
+LL | #[cfg(a())] //~ ERROR invalid predicate `a`
+   |       ^^^
+
+error: literal in `cfg` predicate value must be a string
+  --> $DIR/cfg-attr-syntax-validation.rs:22:11
+   |
+LL | #[cfg(a = 10)] //~ ERROR literal in `cfg` predicate value must be a string
+   |           ^^
+
+error: `cfg` is not a well-formed meta-item
+  --> $DIR/cfg-attr-syntax-validation.rs:27:9
+   |
+LL |         #[cfg(feature = $expr)] //~ ERROR `cfg` is not a well-formed meta-item
+   |         ^^^^^^^^^^^^^^^^^^^^^^^ help: expected syntax is: `#[cfg(/* predicate */)]`
+...
+LL | generate_s9!(concat!("nonexistent"));
+   | ------------------------------------- in this macro invocation
+
+error: aborting due to 9 previous errors
+
+For more information about this error, try `rustc --explain E0537`.

src/test/ui/cfg-empty-codemap.rs

@@ -12,7 +12,7 @@
 
 // compile-flags: --cfg ""
 
-// error-pattern: expected identifier, found
+// error-pattern: invalid `--cfg` argument: `""` (expected `key` or `key="value"`)
 
 pub fn main() {
 }

src/test/ui/issues/issue-31495.rs

@@ -1,13 +0,0 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// compile-flags: --cfg foo(bar)
-// error-pattern: invalid predicate in --cfg command line argument: `foo`
-fn main() {}