Implement built-in attribute macro `#[cfg_eval]`

4 files changed, 196 insertions, 0 deletions

diff --git a/src/test/ui/proc-macro/cfg-eval-fail.rs b/src/test/ui/proc-macro/cfg-eval-fail.rs
new file mode 100644
index 00000000000..379491f3126
--- /dev/null
+++ b/src/test/ui/proc-macro/cfg-eval-fail.rs
@@ -0,0 +1,9 @@
+#![feature(cfg_eval)]
+#![feature(stmt_expr_attributes)]
+
+fn main() {
+    let _ = #[cfg_eval] #[cfg(FALSE)] 0;
+    //~^ ERROR removing an expression is not supported in this position
+    //~| ERROR removing an expression is not supported in this position
+    //~| ERROR removing an expression is not supported in this position
+}
diff --git a/src/test/ui/proc-macro/cfg-eval-fail.stderr b/src/test/ui/proc-macro/cfg-eval-fail.stderr
new file mode 100644
index 00000000000..010ac006b0b
--- /dev/null
+++ b/src/test/ui/proc-macro/cfg-eval-fail.stderr
@@ -0,0 +1,20 @@
+error: removing an expression is not supported in this position
+  --> $DIR/cfg-eval-fail.rs:5:25
+   |
+LL |     let _ = #[cfg_eval] #[cfg(FALSE)] 0;
+   |                         ^^^^^^^^^^^^^
+
+error: removing an expression is not supported in this position
+  --> $DIR/cfg-eval-fail.rs:5:25
+   |
+LL |     let _ = #[cfg_eval] #[cfg(FALSE)] 0;
+   |                         ^^^^^^^^^^^^^
+
+error: removing an expression is not supported in this position
+  --> $DIR/cfg-eval-fail.rs:5:25
+   |
+LL |     let _ = #[cfg_eval] #[cfg(FALSE)] 0;
+   |                         ^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
diff --git a/src/test/ui/proc-macro/cfg-eval.rs b/src/test/ui/proc-macro/cfg-eval.rs
new file mode 100644
index 00000000000..ea397df5452
--- /dev/null
+++ b/src/test/ui/proc-macro/cfg-eval.rs
@@ -0,0 +1,32 @@
+// check-pass
+// compile-flags: -Z span-debug
+// aux-build:test-macros.rs
+
+#![feature(cfg_eval)]
+#![feature(proc_macro_hygiene)]
+#![feature(stmt_expr_attributes)]
+
+#![no_std] // Don't load unnecessary hygiene information from std
+extern crate std;
+
+#[macro_use]
+extern crate test_macros;
+
+#[cfg_eval]
+#[print_attr]
+struct S1 {
+    #[cfg(FALSE)]
+    field_false: u8,
+    #[cfg(all(/*true*/))]
+    #[cfg_attr(FALSE, unknown_attr)]
+    #[cfg_attr(all(/*true*/), allow())]
+    field_true: u8,
+}
+
+#[cfg_eval]
+#[cfg(FALSE)]
+struct S2 {}
+
+fn main() {
+    let _ = #[cfg_eval] #[print_attr](#[cfg(FALSE)] 0, #[cfg(all(/*true*/))] 1);
+}
diff --git a/src/test/ui/proc-macro/cfg-eval.stdout b/src/test/ui/proc-macro/cfg-eval.stdout
new file mode 100644
index 00000000000..b98e8961bfe
--- /dev/null
+++ b/src/test/ui/proc-macro/cfg-eval.stdout
@@ -0,0 +1,135 @@
+PRINT-ATTR INPUT (DISPLAY): struct S1 { #[cfg(all())] #[allow()] field_true : u8, }
+PRINT-ATTR INPUT (DEBUG): TokenStream [
+    Ident {
+        ident: "struct",
+        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+    },
+    Ident {
+        ident: "S1",
+        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+    },
+    Group {
+        delimiter: Brace,
+        stream: TokenStream [
+            Punct {
+                ch: '#',
+                spacing: Alone,
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Group {
+                delimiter: Bracket,
+                stream: TokenStream [
+                    Ident {
+                        ident: "cfg",
+                        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+                    },
+                    Group {
+                        delimiter: Parenthesis,
+                        stream: TokenStream [
+                            Ident {
+                                ident: "all",
+                                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+                            },
+                            Group {
+                                delimiter: Parenthesis,
+                                stream: TokenStream [],
+                                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+                            },
+                        ],
+                        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+                    },
+                ],
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Punct {
+                ch: '#',
+                spacing: Alone,
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Group {
+                delimiter: Bracket,
+                stream: TokenStream [
+                    Ident {
+                        ident: "allow",
+                        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+                    },
+                    Group {
+                        delimiter: Parenthesis,
+                        stream: TokenStream [],
+                        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+                    },
+                ],
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Ident {
+                ident: "field_true",
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Punct {
+                ch: ':',
+                spacing: Alone,
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Ident {
+                ident: "u8",
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+            Punct {
+                ch: ',',
+                spacing: Alone,
+                span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+            },
+        ],
+        span: $DIR/cfg-eval.rs:17:1: 24:2 (#0),
+    },
+]
+PRINT-ATTR INPUT (DISPLAY): (#[cfg(all())] 1,)
+PRINT-ATTR INPUT (DEBUG): TokenStream [
+    Group {
+        delimiter: Parenthesis,
+        stream: TokenStream [
+            Punct {
+                ch: '#',
+                spacing: Alone,
+                span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+            },
+            Group {
+                delimiter: Bracket,
+                stream: TokenStream [
+                    Ident {
+                        ident: "cfg",
+                        span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+                    },
+                    Group {
+                        delimiter: Parenthesis,
+                        stream: TokenStream [
+                            Ident {
+                                ident: "all",
+                                span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+                            },
+                            Group {
+                                delimiter: Parenthesis,
+                                stream: TokenStream [],
+                                span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+                            },
+                        ],
+                        span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+                    },
+                ],
+                span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+            },
+            Literal {
+                kind: Integer,
+                symbol: "1",
+                suffix: None,
+                span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+            },
+            Punct {
+                ch: ',',
+                spacing: Alone,
+                span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+            },
+        ],
+        span: $DIR/cfg-eval.rs:31:38: 31:80 (#0),
+    },
+]