Rollup merge of rust-lang#67795 - Mark-Simulacrum:fmt-argument, r=dtolnay

Cleanup formatting code

This removes a few leftover positional enum variants that were no longer used.

All details that are changed are unstable (and `#[doc(hidden)]`), so this should
not impact downstream code.

Author: JohnTitor

src/libcore/fmt/mod.rs

@@ -10,7 +10,6 @@ use crate::mem;
 use crate::num::flt2dec;
 use crate::ops::Deref;
 use crate::result;
-use crate::slice;
 use crate::str;
 
 mod builders;
@@ -234,8 +233,6 @@ pub struct Formatter<'a> {
     precision: Option<usize>,
 
     buf: &'a mut (dyn Write + 'a),
-    curarg: slice::Iter<'a, ArgumentV1<'a>>,
-    args: &'a [ArgumentV1<'a>],
 }
 
 // NB. Argument is essentially an optimized partially applied formatting function,
@@ -1043,8 +1040,6 @@ pub fn write(output: &mut dyn Write, args: Arguments<'_>) -> Result {
         buf: output,
         align: rt::v1::Alignment::Unknown,
         fill: ' ',
-        args: args.args,
-        curarg: args.args.iter(),
     };
 
     let mut idx = 0;
@@ -1063,7 +1058,7 @@ pub fn write(output: &mut dyn Write, args: Arguments<'_>) -> Result {
             // a string piece.
             for (arg, piece) in fmt.iter().zip(args.pieces.iter()) {
                 formatter.buf.write_str(*piece)?;
-                formatter.run(arg)?;
+                run(&mut formatter, arg, &args.args)?;
                 idx += 1;
             }
         }
@@ -1077,6 +1072,39 @@ pub fn write(output: &mut dyn Write, args: Arguments<'_>) -> Result {
     Ok(())
 }
 
+fn run(fmt: &mut Formatter<'_>, arg: &rt::v1::Argument, args: &[ArgumentV1<'_>]) -> Result {
+    fmt.fill = arg.format.fill;
+    fmt.align = arg.format.align;
+    fmt.flags = arg.format.flags;
+    fmt.width = getcount(args, &arg.format.width);
+    fmt.precision = getcount(args, &arg.format.precision);
+
+    // Extract the correct argument
+    let value = {
+        #[cfg(bootstrap)]
+        {
+            match arg.position {
+                rt::v1::Position::At(i) => args[i],
+            }
+        }
+        #[cfg(not(bootstrap))]
+        {
+            args[arg.position]
+        }
+    };
+
+    // Then actually do some printing
+    (value.formatter)(value.value, fmt)
+}
+
+fn getcount(args: &[ArgumentV1<'_>], cnt: &rt::v1::Count) -> Option<usize> {
+    match *cnt {
+        rt::v1::Count::Is(n) => Some(n),
+        rt::v1::Count::Implied => None,
+        rt::v1::Count::Param(i) => args[i].as_usize(),
+    }
+}
+
 /// Padding after the end of something. Returned by `Formatter::padding`.
 #[must_use = "don't forget to write the post padding"]
 struct PostPadding {
@@ -1114,41 +1142,6 @@ impl<'a> Formatter<'a> {
             align: self.align,
             width: self.width,
             precision: self.precision,
-
-            // These only exist in the struct for the `run` method,
-            // which won’t be used together with this method.
-            curarg: self.curarg.clone(),
-            args: self.args,
-        }
-    }
-
-    // First up is the collection of functions used to execute a format string
-    // at runtime. This consumes all of the compile-time statics generated by
-    // the format! syntax extension.
-    fn run(&mut self, arg: &rt::v1::Argument) -> Result {
-        // Fill in the format parameters into the formatter
-        self.fill = arg.format.fill;
-        self.align = arg.format.align;
-        self.flags = arg.format.flags;
-        self.width = self.getcount(&arg.format.width);
-        self.precision = self.getcount(&arg.format.precision);
-
-        // Extract the correct argument
-        let value = match arg.position {
-            rt::v1::Position::Next => *self.curarg.next().unwrap(),
-            rt::v1::Position::At(i) => self.args[i],
-        };
-
-        // Then actually do some printing
-        (value.formatter)(value.value, self)
-    }
-
-    fn getcount(&mut self, cnt: &rt::v1::Count) -> Option<usize> {
-        match *cnt {
-            rt::v1::Count::Is(n) => Some(n),
-            rt::v1::Count::Implied => None,
-            rt::v1::Count::Param(i) => self.args[i].as_usize(),
-            rt::v1::Count::NextParam => self.curarg.next()?.as_usize(),
         }
     }
 

src/libcore/fmt/rt/v1.rs

@@ -7,7 +7,10 @@
 
 #[derive(Copy, Clone)]
 pub struct Argument {
+    #[cfg(bootstrap)]
     pub position: Position,
+    #[cfg(not(bootstrap))]
+    pub position: usize,
     pub format: FormatSpec,
 }
 
@@ -37,12 +40,11 @@ pub enum Alignment {
 pub enum Count {
     Is(usize),
     Param(usize),
-    NextParam,
     Implied,
 }
 
+#[cfg(bootstrap)]
 #[derive(Copy, Clone)]
 pub enum Position {
-    Next,
     At(usize),
 }

src/librustc_builtin_macros/format.rs

@@ -590,17 +590,6 @@ impl<'a, 'b> Context<'a, 'b> {
             parse::NextArgument(ref arg) => {
                 // Build the position
                 let pos = {
-                    let pos = |c, arg| {
-                        let mut path = Context::rtpath(self.ecx, "Position");
-                        path.push(self.ecx.ident_of(c, sp));
-                        match arg {
-                            Some(i) => {
-                                let arg = self.ecx.expr_usize(sp, i);
-                                self.ecx.expr_call_global(sp, path, vec![arg])
-                            }
-                            None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
-                        }
-                    };
                     match arg.position {
                         parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => {
                             // Map to index in final generated argument array
@@ -615,7 +604,7 @@ impl<'a, 'b> Context<'a, 'b> {
                                     arg_idx
                                 }
                             };
-                            pos("At", Some(arg_idx))
+                            self.ecx.expr_usize(sp, arg_idx)
                         }
 
                         // should never be the case, because names are already

src/test/ui/async-await/async-fn-nonsend.rs

@@ -2,15 +2,15 @@
 // edition:2018
 // compile-flags: --crate-type lib
 
-use std::{
-    cell::RefCell,
-    fmt::Debug,
-    rc::Rc,
-};
+use std::{cell::RefCell, fmt::Debug, rc::Rc};
 
-fn non_sync() -> impl Debug { RefCell::new(()) }
+fn non_sync() -> impl Debug {
+    RefCell::new(())
+}
 
-fn non_send() -> impl Debug { Rc::new(()) }
+fn non_send() -> impl Debug {
+    Rc::new(())
+}
 
 fn take_ref<T>(_: &T) {}
 
@@ -53,5 +53,4 @@ pub fn pass_assert() {
     //~^ ERROR future cannot be sent between threads safely
     assert_send(non_sync_with_method_call());
     //~^ ERROR future cannot be sent between threads safely
-    //~^^ ERROR future cannot be sent between threads safely
 }

src/test/ui/async-await/async-fn-nonsend.stderr

@@ -62,27 +62,5 @@ LL |     }
 LL | }
    | - `f` is later dropped here
 
-error: future cannot be sent between threads safely
-  --> $DIR/async-fn-nonsend.rs:54:5
-   |
-LL | fn assert_send(_: impl Send) {}
-   |    -----------         ---- required by this bound in `assert_send`
-...
-LL |     assert_send(non_sync_with_method_call());
-   |     ^^^^^^^^^^^ future returned by `non_sync_with_method_call` is not `Send`
-   |
-   = help: within `std::fmt::ArgumentV1<'_>`, the trait `std::marker::Sync` is not implemented for `*mut (dyn std::ops::Fn() + 'static)`
-note: future is not `Send` as this value is used across an await
-  --> $DIR/async-fn-nonsend.rs:43:9
-   |
-LL |     let f: &mut std::fmt::Formatter = panic!();
-   |         - has type `&mut std::fmt::Formatter<'_>`
-LL |     if non_sync().fmt(f).unwrap() == () {
-LL |         fut().await;
-   |         ^^^^^^^^^^^ await occurs here, with `f` maybe used later
-LL |     }
-LL | }
-   | - `f` is later dropped here
-
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors