Rollup merge of #65884 - Centril:non-hardcoded-abis, r=petrochenkov

syntax: ABI-oblivious grammar

This PR has the following effects:

1. `extern $lit` is now legal where `$lit:literal` and `$lit` is substituted for a string literal.

2. `extern "abi_that_does_not_exist"` is now *syntactically* legal whereas before, the set of ABI strings was hard-coded into the grammar of the language. With this PR, the set of ABIs are instead validated and translated during lowering. That seems more appropriate.

3. `ast::FloatTy` is now distinct from `rustc_target::abi::FloatTy`. The former is used substantially more and the translation between them is only necessary in a single place.

4. As a result of 2-3, libsyntax no longer depends on librustc_target, which should improve pipe-lining somewhat.

cc @rust-lang/lang -- the points 1-2 slightly change the definition of the language but in a way which seems consistent with our general principles (in particular wrt. the discussions of turning things into semantic errors). I expect this to be uncontroversial but it's worth letting y'all know. :)

r? @varkor

Author: Centril

Cargo.lock

@@ -3762,7 +3762,6 @@ dependencies = [
  "rustc",
  "rustc_codegen_utils",
  "rustc_data_structures",
- "rustc_target",
  "serde_json",
  "syntax",
  "syntax_pos",
@@ -4362,7 +4361,6 @@ dependencies = [
  "rustc_errors",
  "rustc_index",
  "rustc_lexer",
- "rustc_target",
  "scoped-tls",
  "serialize",
  "smallvec 1.0.0",
@@ -4380,7 +4378,6 @@ dependencies = [
  "rustc_errors",
  "rustc_index",
  "rustc_lexer",
- "rustc_target",
  "scoped-tls",
  "serialize",
  "smallvec 1.0.0",

src/librustc/error_codes.rs

@@ -2336,6 +2336,7 @@ the future, [RFC 2091] prohibits their implementation without a follow-up RFC.
     E0657, // `impl Trait` can only capture lifetimes bound at the fn level
     E0687, // in-band lifetimes cannot be used in `fn`/`Fn` syntax
     E0688, // in-band lifetimes cannot be mixed with explicit lifetime binders
+    E0703, // invalid ABI
 //  E0707, // multiple elided lifetimes used in arguments of `async fn`
     E0708, // `async` non-`move` closures with parameters are not currently
            // supported

src/librustc/hir/lowering.rs

@@ -1216,7 +1216,7 @@ impl<'a> LoweringContext<'a> {
                                     ImplTraitContext::disallowed(),
                                 ),
                                 unsafety: this.lower_unsafety(f.unsafety),
-                                abi: f.abi,
+                                abi: this.lower_abi(f.abi),
                                 decl: this.lower_fn_decl(&f.decl, None, false, None),
                                 param_names: this.lower_fn_params_to_names(&f.decl),
                             }))

src/librustc/hir/lowering/item.rs

@@ -12,6 +12,7 @@ use crate::hir::def::{Res, DefKind};
 use crate::util::nodemap::NodeMap;
 
 use rustc_data_structures::thin_vec::ThinVec;
+use rustc_target::spec::abi;
 
 use std::collections::BTreeSet;
 use smallvec::SmallVec;
@@ -735,7 +736,7 @@ impl LoweringContext<'_> {
 
     fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
         hir::ForeignMod {
-            abi: fm.abi,
+            abi: self.lower_abi(fm.abi),
             items: fm.items
                 .iter()
                 .map(|x| self.lower_foreign_item(x))
@@ -1291,10 +1292,30 @@ impl LoweringContext<'_> {
             unsafety: self.lower_unsafety(h.unsafety),
             asyncness: self.lower_asyncness(h.asyncness.node),
             constness: self.lower_constness(h.constness),
-            abi: h.abi,
+            abi: self.lower_abi(h.abi),
         }
     }
 
+    pub(super) fn lower_abi(&mut self, abi: Abi) -> abi::Abi {
+        abi::lookup(&abi.symbol.as_str()).unwrap_or_else(|| {
+            self.error_on_invalid_abi(abi);
+            abi::Abi::Rust
+        })
+    }
+
+    fn error_on_invalid_abi(&self, abi: Abi) {
+        struct_span_err!(
+            self.sess,
+            abi.span,
+            E0703,
+            "invalid ABI: found `{}`",
+            abi.symbol
+        )
+        .span_label(abi.span, "invalid ABI")
+        .help(&format!("valid ABIs: {}", abi::all_names().join(", ")))
+        .emit();
+    }
+
     pub(super) fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
         match u {
             Unsafety::Unsafe => hir::Unsafety::Unsafe,

src/librustc/ich/impls_syntax.rs

@@ -124,7 +124,6 @@ for ::syntax::attr::StabilityLevel {
 
 impl_stable_hash_for!(struct ::syntax::attr::RustcDeprecation { since, reason, suggestion });
 
-
 impl_stable_hash_for!(enum ::syntax::attr::IntType {
     SignedInt(int_ty),
     UnsignedInt(uint_ty)
@@ -136,6 +135,11 @@ impl_stable_hash_for!(enum ::syntax::ast::LitIntType {
     Unsuffixed
 });
 
+impl_stable_hash_for!(enum ::syntax::ast::LitFloatType {
+    Suffixed(float_ty),
+    Unsuffixed
+});
+
 impl_stable_hash_for!(struct ::syntax::ast::Lit {
     kind,
     token,
@@ -148,8 +152,7 @@ impl_stable_hash_for!(enum ::syntax::ast::LitKind {
     Byte(value),
     Char(value),
     Int(value, lit_int_type),
-    Float(value, float_ty),
-    FloatUnsuffixed(value),
+    Float(value, lit_float_type),
     Bool(value),
     Err(value)
 });
@@ -159,6 +162,7 @@ impl_stable_hash_for_spanned!(::syntax::ast::LitKind);
 impl_stable_hash_for!(enum ::syntax::ast::IntTy { Isize, I8, I16, I32, I64, I128 });
 impl_stable_hash_for!(enum ::syntax::ast::UintTy { Usize, U8, U16, U32, U64, U128 });
 impl_stable_hash_for!(enum ::syntax::ast::FloatTy { F32, F64 });
+impl_stable_hash_for!(enum ::rustc_target::abi::FloatTy { F32, F64 });
 impl_stable_hash_for!(enum ::syntax::ast::Unsafety { Unsafe, Normal });
 impl_stable_hash_for!(enum ::syntax::ast::Constness { Const, NotConst });
 impl_stable_hash_for!(enum ::syntax::ast::Defaultness { Default, Final });

src/librustc/ty/layout.rs

@@ -538,7 +538,10 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
             ty::Uint(ity) => {
                 scalar(Int(Integer::from_attr(dl, attr::UnsignedInt(ity)), false))
             }
-            ty::Float(fty) => scalar(Float(fty)),
+            ty::Float(fty) => scalar(Float(match fty {
+                ast::FloatTy::F32 => FloatTy::F32,
+                ast::FloatTy::F64 => FloatTy::F64,
+            })),
             ty::FnPtr(_) => {
                 let mut ptr = scalar_unit(Pointer);
                 ptr.valid_range = 1..=*ptr.valid_range.end();

src/librustc/ty/print/obsolete.rs

@@ -12,7 +12,6 @@ use rustc::ty::{self, Const, Instance, Ty, TyCtxt};
 use rustc::{bug, hir};
 use std::fmt::Write;
 use std::iter;
-use syntax::ast;
 
 /// Same as `unique_type_name()` but with the result pushed onto the given
 /// `output` parameter.
@@ -39,20 +38,9 @@ impl DefPathBasedNames<'tcx> {
             ty::Char => output.push_str("char"),
             ty::Str => output.push_str("str"),
             ty::Never => output.push_str("!"),
-            ty::Int(ast::IntTy::Isize) => output.push_str("isize"),
-            ty::Int(ast::IntTy::I8) => output.push_str("i8"),
-            ty::Int(ast::IntTy::I16) => output.push_str("i16"),
-            ty::Int(ast::IntTy::I32) => output.push_str("i32"),
-            ty::Int(ast::IntTy::I64) => output.push_str("i64"),
-            ty::Int(ast::IntTy::I128) => output.push_str("i128"),
-            ty::Uint(ast::UintTy::Usize) => output.push_str("usize"),
-            ty::Uint(ast::UintTy::U8) => output.push_str("u8"),
-            ty::Uint(ast::UintTy::U16) => output.push_str("u16"),
-            ty::Uint(ast::UintTy::U32) => output.push_str("u32"),
-            ty::Uint(ast::UintTy::U64) => output.push_str("u64"),
-            ty::Uint(ast::UintTy::U128) => output.push_str("u128"),
-            ty::Float(ast::FloatTy::F32) => output.push_str("f32"),
-            ty::Float(ast::FloatTy::F64) => output.push_str("f64"),
+            ty::Int(ty) => output.push_str(ty.name_str()),
+            ty::Uint(ty) => output.push_str(ty.name_str()),
+            ty::Float(ty) => output.push_str(ty.name_str()),
             ty::Adt(adt_def, substs) => {
                 self.push_def_path(adt_def.did, output);
                 self.push_generic_params(substs, iter::empty(), output, debug);

src/librustc/ty/print/pretty.rs

@@ -466,9 +466,9 @@ pub trait PrettyPrinter<'tcx>:
         match ty.kind {
             ty::Bool => p!(write("bool")),
             ty::Char => p!(write("char")),
-            ty::Int(t) => p!(write("{}", t.ty_to_string())),
-            ty::Uint(t) => p!(write("{}", t.ty_to_string())),
-            ty::Float(t) => p!(write("{}", t.ty_to_string())),
+            ty::Int(t) => p!(write("{}", t.name_str())),
+            ty::Uint(t) => p!(write("{}", t.name_str())),
+            ty::Float(t) => p!(write("{}", t.name_str())),
             ty::RawPtr(ref tm) => {
                 p!(write("*{} ", match tm.mutbl {
                     hir::MutMutable => "mut",
@@ -895,10 +895,11 @@ pub trait PrettyPrinter<'tcx>:
                 let bit_size = Integer::from_attr(&self.tcx(), UnsignedInt(*ui)).size();
                 let max = truncate(u128::max_value(), bit_size);
 
+                let ui_str = ui.name_str();
                 if data == max {
-                    p!(write("std::{}::MAX", ui))
+                    p!(write("std::{}::MAX", ui_str))
                 } else {
-                    p!(write("{}{}", data, ui))
+                    p!(write("{}{}", data, ui_str))
                 };
             },
             (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Int(i)) => {
@@ -911,10 +912,11 @@ pub trait PrettyPrinter<'tcx>:
                 let size = self.tcx().layout_of(ty::ParamEnv::empty().and(ty))
                     .unwrap()
                     .size;
+                let i_str = i.name_str();
                 match data {
-                    d if d == min => p!(write("std::{}::MIN", i)),
-                    d if d == max => p!(write("std::{}::MAX", i)),
-                    _ => p!(write("{}{}", sign_extend(data, size) as i128, i))
+                    d if d == min => p!(write("std::{}::MIN", i_str)),
+                    d if d == max => p!(write("std::{}::MAX", i_str)),
+                    _ => p!(write("{}{}", sign_extend(data, size) as i128, i_str))
                 }
             },
             (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Char) =>

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -843,13 +843,13 @@ fn basic_type_metadata(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>) -> &'ll DIType {
         ty::Bool => ("bool", DW_ATE_boolean),
         ty::Char => ("char", DW_ATE_unsigned_char),
         ty::Int(int_ty) => {
-            (int_ty.ty_to_string(), DW_ATE_signed)
+            (int_ty.name_str(), DW_ATE_signed)
         },
         ty::Uint(uint_ty) => {
-            (uint_ty.ty_to_string(), DW_ATE_unsigned)
+            (uint_ty.name_str(), DW_ATE_unsigned)
         },
         ty::Float(float_ty) => {
-            (float_ty.ty_to_string(), DW_ATE_float)
+            (float_ty.name_str(), DW_ATE_float)
         },
         _ => bug!("debuginfo::basic_type_metadata - t is invalid type")
     };

src/librustc_codegen_llvm/intrinsic.rs

@@ -18,8 +18,8 @@ use rustc::ty::layout::{self, LayoutOf, HasTyCtxt, Primitive};
 use rustc::mir::interpret::GlobalId;
 use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
 use rustc::hir;
-use syntax::ast::{self, FloatTy};
-use rustc_target::abi::HasDataLayout;
+use rustc_target::abi::{FloatTy, HasDataLayout};
+use syntax::ast;
 
 use rustc_codegen_ssa::common::span_invalid_monomorphization_error;
 use rustc_codegen_ssa::traits::*;
@@ -1335,7 +1335,7 @@ fn generic_simd_intrinsic(
             },
             ty::Float(f) => {
                 return_error!("unsupported element type `{}` of floating-point vector `{}`",
-                              f, in_ty);
+                              f.name_str(), in_ty);
             },
             _ => {
                 return_error!("`{}` is not a floating-point type", in_ty);