Rollup merge of #72308 - Aaron1011:fix/hygiene-error-message, r=matthewjasper

Emit a better diagnostic when function actually has a 'self' parameter

Fixes #66898

When we are unable to resolve a reference to `self`, we current assume
that the containing function doesn't have a `self` parameter, and
emit an error message accordingly.

However, if the reference to `self` was created by a macro invocation,
then resolution will correctly fail, due to hygiene. In this case, we
don't want to tell the user that the containing fuction doesn't have a
'self' paramter if it actually has one.

This PR checks for the precense of a 'self' parameter, and adjusts the
error message we emit accordingly.

TODO: The exact error message we emit could probably be improved. Should
we explicitly mention hygiene?

src/test/ui/hygiene/missing-self-diag.rs

@@ -0,0 +1,23 @@
+// Regression test for issue #66898
+// Tests that we don't emit a nonsensical error message
+// when a macro invocation tries to access `self` from a function
+// that has a 'self' parameter
+
+pub struct Foo;
+
+macro_rules! call_bar {
+    () => {
+        self.bar(); //~ ERROR expected value
+    }
+}
+
+impl Foo {
+    pub fn foo(&self) {
+        call_bar!();
+    }
+
+    pub fn bar(&self) {
+    }
+}
+
+fn main() {}

src/test/ui/hygiene/missing-self-diag.stderr

@@ -0,0 +1,17 @@
+error[E0424]: expected value, found module `self`
+  --> $DIR/missing-self-diag.rs:10:9
+   |
+LL |           self.bar();
+   |           ^^^^ `self` value is a keyword only available in methods with a `self` parameter
+...
+LL | /     pub fn foo(&self) {
+LL | |         call_bar!();
+   | |         ------------ in this macro invocation
+LL | |     }
+   | |_____- this function has a `self` parameter, but a macro invocation can only access identifiers it receives from parameters
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0424`.