Auto merge of #67133 - oli-obk:it_must_be_a_sign, r=eddyb

Deduplicate pretty printing of constants

r? @eddyb for the pretty printing logic
cc @RalfJung

Author: bors

src/librustc/mir/mod.rs

@@ -2562,15 +2562,15 @@ impl<'tcx> Debug for Constant<'tcx> {
 
 impl<'tcx> Display for Constant<'tcx> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
+        use crate::ty::print::PrettyPrinter;
         write!(fmt, "const ")?;
-        // FIXME make the default pretty printing of raw pointers more detailed. Here we output the
-        // debug representation of raw pointers, so that the raw pointers in the mir dump output are
-        // detailed and just not '{pointer}'.
-        if let ty::RawPtr(_) = self.literal.ty.kind {
-            write!(fmt, "{:?} : {}", self.literal.val, self.literal.ty)
-        } else {
-            write!(fmt, "{}", self.literal)
-        }
+        ty::tls::with(|tcx| {
+            let literal = tcx.lift(&self.literal).unwrap();
+            let mut cx = FmtPrinter::new(tcx, fmt, Namespace::ValueNS);
+            cx.print_alloc_ids = true;
+            cx.pretty_print_const(literal, true)?;
+            Ok(())
+        })
     }
 }
 

src/librustc/ty/print/pretty.rs

@@ -157,6 +157,7 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
         }
     }
 }
+
 impl PrettyPrinter<'tcx> for AbsolutePathPrinter<'tcx> {
     fn region_should_not_be_omitted(&self, _region: ty::Region<'_>) -> bool {
         false

src/librustc_mir/interpret/intrinsics/type_name.rs

@@ -3,18 +3,20 @@
 
 use std::convert::{TryFrom, TryInto};
 
-use rustc::ty::layout::{
-    self, HasDataLayout, IntegerExt, LayoutOf, PrimitiveExt, Size, TyLayout, VariantIdx,
-};
-use rustc::{mir, ty};
-
 use super::{InterpCx, MPlaceTy, Machine, MemPlace, Place, PlaceTy};
 pub use rustc::mir::interpret::ScalarMaybeUndef;
 use rustc::mir::interpret::{
     sign_extend, truncate, AllocId, ConstValue, GlobalId, InterpResult, Pointer, Scalar,
 };
-use rustc_ast::ast;
+use rustc::ty::layout::{
+    self, HasDataLayout, IntegerExt, LayoutOf, PrimitiveExt, Size, TyLayout, VariantIdx,
+};
+use rustc::ty::print::{FmtPrinter, PrettyPrinter, Printer};
+use rustc::ty::Ty;
+use rustc::{mir, ty};
+use rustc_hir::def::Namespace;
 use rustc_macros::HashStable;
+use std::fmt::Write;
 
 /// An `Immediate` represents a single immediate self-contained Rust value.
 ///
@@ -92,47 +94,44 @@ pub struct ImmTy<'tcx, Tag = ()> {
     pub layout: TyLayout<'tcx>,
 }
 
-// `Tag: Copy` because some methods on `Scalar` consume them by value
 impl<Tag: Copy> std::fmt::Display for ImmTy<'tcx, Tag> {
-    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match &self.imm {
-            // We cannot use `to_bits_or_ptr` as we do not have a `tcx`.
-            // So we use `is_bits` and circumvent a bunch of sanity checking -- but
-            // this is anyway only for printing.
-            Immediate::Scalar(ScalarMaybeUndef::Scalar(s)) if s.is_ptr() => {
-                fmt.write_str("{pointer}")
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        /// Helper function for printing a scalar to a FmtPrinter
+        fn p<'a, 'tcx, F: std::fmt::Write, Tag>(
+            cx: FmtPrinter<'a, 'tcx, F>,
+            s: ScalarMaybeUndef<Tag>,
+            ty: Ty<'tcx>,
+        ) -> Result<FmtPrinter<'a, 'tcx, F>, std::fmt::Error> {
+            match s {
+                ScalarMaybeUndef::Scalar(s) => {
+                    cx.pretty_print_const_scalar(s.erase_tag(), ty, true)
+                }
+                ScalarMaybeUndef::Undef => cx.typed_value(
+                    |mut this| {
+                        this.write_str("{undef ")?;
+                        Ok(this)
+                    },
+                    |this| this.print_type(ty),
+                    " ",
+                ),
             }
-            Immediate::Scalar(ScalarMaybeUndef::Scalar(s)) => {
-                let s = s.assert_bits(self.layout.size);
-                match self.layout.ty.kind {
-                    ty::Int(_) => {
-                        return write!(fmt, "{}", super::sign_extend(s, self.layout.size) as i128,);
-                    }
-                    ty::Uint(_) => return write!(fmt, "{}", s),
-                    ty::Bool if s == 0 => return fmt.write_str("false"),
-                    ty::Bool if s == 1 => return fmt.write_str("true"),
-                    ty::Char => {
-                        if let Some(c) = u32::try_from(s).ok().and_then(std::char::from_u32) {
-                            return write!(fmt, "{}", c);
-                        }
-                    }
-                    ty::Float(ast::FloatTy::F32) => {
-                        if let Ok(u) = u32::try_from(s) {
-                            return write!(fmt, "{}", f32::from_bits(u));
-                        }
-                    }
-                    ty::Float(ast::FloatTy::F64) => {
-                        if let Ok(u) = u64::try_from(s) {
-                            return write!(fmt, "{}", f64::from_bits(u));
-                        }
+        }
+        ty::tls::with(|tcx| {
+            match self.imm {
+                Immediate::Scalar(s) => {
+                    if let Some(ty) = tcx.lift(&self.layout.ty) {
+                        let cx = FmtPrinter::new(tcx, f, Namespace::ValueNS);
+                        p(cx, s, ty)?;
+                        return Ok(());
                     }
-                    _ => {}
+                    write!(f, "{:?}: {}", s.erase_tag(), self.layout.ty)
+                }
+                Immediate::ScalarPair(a, b) => {
+                    // FIXME(oli-obk): at least print tuples and slices nicely
+                    write!(f, "({:?}, {:?}): {}", a.erase_tag(), b.erase_tag(), self.layout.ty,)
                 }
-                write!(fmt, "{:x}", s)
             }
-            Immediate::Scalar(ScalarMaybeUndef::Undef) => fmt.write_str("{undef}"),
-            Immediate::ScalarPair(..) => fmt.write_str("{wide pointer or tuple}"),
-        }
+        })
     }
 }
 

src/librustc_mir/interpret/operand.rs

@@ -14,7 +14,7 @@ fn main() {}
 // START rustc.FOO.PromoteTemps.before.mir
 // bb0: {
 // ...
-//     _5 = const Scalar(alloc1+0) : &i32;
+//     _5 = const {alloc1+0: &i32};
 //     _4 = &(*_5);
 //     _3 = [move _4];
 //     _2 = &_3;
@@ -31,7 +31,7 @@ fn main() {}
 // START rustc.BAR.PromoteTemps.before.mir
 // bb0: {
 // ...
-//     _5 = const Scalar(alloc0+0) : &i32;
+//     _5 = const {alloc0+0: &i32};
 //     _4 = &(*_5);
 //     _3 = [move _4];
 //     _2 = &_3;

src/test/mir-opt/const-promotion-extern-static.rs

@@ -31,7 +31,7 @@ fn main() {
 // START rustc.main.ConstProp.after.mir
 //  bb0: {
 //      ...
-//      _3 = const Scalar(0x01) : std::option::Option<bool>;
+//      _3 = const {transmute(0x01): std::option::Option<bool>};
 //      _4 = const 1isize;
 //      switchInt(const 1isize) -> [1isize: bb2, otherwise: bb1];
 //  }

src/test/mir-opt/const_prop/discriminant.rs

@@ -29,7 +29,7 @@ fn main() {
 // START rustc.main.ConstProp.after.mir
 //  bb0: {
 //      ...
-//      _3 = const Scalar(<ZST>) : ();
+//      _3 = const ();
 //      _2 = (move _3, const 0u8, const 0u8);
 //      ...
 //      _1 = const encode(move _2) -> bb1;

src/test/mir-opt/const_prop/issue-66971.rs

@@ -10,10 +10,10 @@ fn main() {
 // START rustc.main.ConstProp.before.mir
 //  bb0: {
 //      ...
-//      _3 = const Scalar(alloc0+0) : &u8;
+//      _3 = const {alloc0+0: &u8};
 //      _2 = (*_3);
 //      ...
-//      _5 = const Scalar(alloc0+0) : &u8;
+//      _5 = const {alloc0+0: &u8};
 //      _4 = (*_5);
 //      _1 = Add(move _2, move _4);
 //      ...

src/test/mir-opt/const_prop/read_immutable_static.rs

@@ -1,18 +1,18 @@
 // compile-flags: -C overflow-checks=no
 
-fn use_zst(_: ((), ())) { }
+fn use_zst(_: ((), ())) {}
 
 struct Temp {
-    x: u8
+    x: u8,
 }
 
-fn use_u8(_: u8) { }
+fn use_u8(_: u8) {}
 
 fn main() {
     let ((), ()) = ((), ());
     use_zst(((), ()));
 
-    use_u8((Temp { x : 40 }).x + 2);
+    use_u8((Temp { x: 40 }).x + 2);
 }
 
 // END RUST SOURCE
@@ -35,28 +35,28 @@ fn main() {
 // bb0: {
 //   StorageLive(_1);
 //   StorageLive(_2);
-//   _2 = const Scalar(<ZST>) : ();
+//   _2 = const ();
 //   StorageLive(_3);
-//   _3 = const Scalar(<ZST>) : ();
-//   _1 = const Scalar(<ZST>) : ((), ());
+//   _3 = const ();
+//   _1 = const {transmute(()): ((), ())};
 //   StorageDead(_3);
 //   StorageDead(_2);
 //   StorageDead(_1);
 //   StorageLive(_4);
 //   StorageLive(_6);
-//   _6 = const Scalar(<ZST>) : ();
+//   _6 = const ();
 //   StorageLive(_7);
-//   _7 = const Scalar(<ZST>) : ();
+//   _7 = const ();
 //   StorageDead(_7);
 //   StorageDead(_6);
-//   _4 = const use_zst(const Scalar(<ZST>) : ((), ())) -> bb1;
+//   _4 = const use_zst(const {transmute(()): ((), ())}) -> bb1;
 // }
 // bb1: {
 //   StorageDead(_4);
 //   StorageLive(_8);
 //   StorageLive(_10);
 //   StorageLive(_11);
-//   _11 = const Scalar(0x28) : Temp;
+//   _11 = const {transmute(0x28) : Temp};
 //   _10 = const 40u8;
 //   StorageDead(_10);
 //   _8 = const use_u8(const 42u8) -> bb2;
@@ -75,7 +75,7 @@ fn main() {
 // }
 // bb0: {
 //   StorageLive(_1);
-//   _1 = const use_zst(const Scalar(<ZST>) : ((), ())) -> bb1;
+//   _1 = const use_zst(const {transmute(()): ((), ())}) -> bb1;
 // }
 // bb1: {
 //   StorageDead(_1);

src/test/mir-opt/simplify-locals-removes-unused-consts.rs

@@ -10,7 +10,7 @@ error[E0282]: type annotations needed
   --> $DIR/cannot-infer-const-args.rs:9:5
    |
 LL |     foo();
-   |     ^^^ cannot infer type for fn item `fn() -> usize {foo::<_: usize>}`
+   |     ^^^ cannot infer type for fn item `fn() -> usize {foo::<{_: usize}>}`
 
 error: aborting due to previous error