From c4a8d7f86a5d54a2f3b3875e703d06acd12ae7cc Mon Sep 17 00:00:00 2001
From: Mark Rousskov <mark.simulacrum@gmail.com>
Date: Tue, 1 Sep 2020 17:12:38 -0400
Subject: [PATCH] Introduce missing ABI lint on extern blocks
---
Cargo.lock | 1 +
compiler/rustc_ast_lowering/src/item.rs | 17 ++++++++++------
compiler/rustc_ast_lowering/src/lib.rs | 24 ++++++++++++++++++++++-
compiler/rustc_lint/src/context.rs | 4 ++++
compiler/rustc_lint_defs/Cargo.toml | 1 +
compiler/rustc_lint_defs/src/builtin.rs | 26 +++++++++++++++++++++++++
compiler/rustc_lint_defs/src/lib.rs | 2 ++
7 files changed, 68 insertions(+), 7 deletions(-)
diff --git a/Cargo.lock b/Cargo.lock
index ab452c97e7b..a24ab967e5c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3896,6 +3896,7 @@ dependencies = [
"rustc_macros",
"rustc_serialize",
"rustc_span",
+ "rustc_target",
"tracing",
]
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 4e9f9d66c5b..7666b25b6d7 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -317,12 +317,17 @@ impl<'hir> LoweringContext<'_, 'hir> {
})
}
ItemKind::Mod(ref m) => hir::ItemKind::Mod(self.lower_mod(m)),
- ItemKind::ForeignMod(ref fm) => hir::ItemKind::ForeignMod {
- abi: fm.abi.map_or(abi::Abi::C, |abi| self.lower_abi(abi)),
- items: self
- .arena
- .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))),
- },
+ ItemKind::ForeignMod(ref fm) => {
+ if fm.abi.is_none() {
+ self.maybe_lint_missing_abi(span, id, abi::Abi::C);
+ }
+ hir::ItemKind::ForeignMod {
+ abi: fm.abi.map_or(abi::Abi::C, |abi| self.lower_abi(abi)),
+ items: self
+ .arena
+ .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))),
+ }
+ }
ItemKind::GlobalAsm(ref ga) => hir::ItemKind::GlobalAsm(self.lower_global_asm(ga)),
ItemKind::TyAlias(_, ref gen, _, Some(ref ty)) => {
// We lower
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 89557c29dd1..59e55fc4ee7 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -53,13 +53,15 @@ use rustc_hir::definitions::{DefKey, DefPathData, Definitions};
use rustc_hir::intravisit;
use rustc_hir::{ConstArg, GenericArg, ParamName};
use rustc_index::vec::{Idx, IndexVec};
-use rustc_session::lint::{builtin::BARE_TRAIT_OBJECTS, BuiltinLintDiagnostics, LintBuffer};
+use rustc_session::lint::builtin::{BARE_TRAIT_OBJECTS, MISSING_ABI};
+use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
use rustc_session::parse::ParseSess;
use rustc_session::Session;
use rustc_span::hygiene::ExpnId;
use rustc_span::source_map::{respan, DesugaringKind};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::Span;
+use rustc_target::spec::abi::Abi;
use smallvec::{smallvec, SmallVec};
use std::collections::BTreeMap;
@@ -2777,6 +2779,26 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
)
}
}
+
+ fn maybe_lint_missing_abi(&mut self, span: Span, id: NodeId, default: Abi) {
+ // FIXME(davidtwco): This is a hack to detect macros which produce spans of the
+ // call site which do not have a macro backtrace. See #61963.
+ let is_macro_callsite = self
+ .sess
+ .source_map()
+ .span_to_snippet(span)
+ .map(|snippet| snippet.starts_with("#["))
+ .unwrap_or(true);
+ if !is_macro_callsite {
+ self.resolver.lint_buffer().buffer_lint_with_diagnostic(
+ MISSING_ABI,
+ id,
+ span,
+ "extern declarations without an explicit ABI are deprecated",
+ BuiltinLintDiagnostics::MissingAbi(span, default),
+ )
+ }
+ }
}
fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body<'_>>) -> Vec<hir::BodyId> {
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index f4740be34cb..0f40324acb1 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -600,6 +600,10 @@ pub trait LintContext: Sized {
BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
db.span_suggestion(span, "remove `mut` from the parameter", ident.to_string(), Applicability::MachineApplicable);
}
+ BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
+ db.span_label(span, "ABI should be specified here");
+ db.help(&format!("the default ABI is {}", default_abi.name()));
+ }
}
// Rewrap `db`, and pass control to the user.
decorate(LintDiagnosticBuilder::new(db));
diff --git a/compiler/rustc_lint_defs/Cargo.toml b/compiler/rustc_lint_defs/Cargo.toml
index 7f908088cf5..f909f159784 100644
--- a/compiler/rustc_lint_defs/Cargo.toml
+++ b/compiler/rustc_lint_defs/Cargo.toml
@@ -11,3 +11,4 @@ rustc_data_structures = { path = "../rustc_data_structures" }
rustc_span = { path = "../rustc_span" }
rustc_serialize = { path = "../rustc_serialize" }
rustc_macros = { path = "../rustc_macros" }
+rustc_target = { path = "../rustc_target" }
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index f90fc7fc9ab..e9632796704 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -2917,6 +2917,7 @@ declare_lint_pass! {
FUNCTION_ITEM_REFERENCES,
USELESS_DEPRECATED,
UNSUPPORTED_NAKED_FUNCTIONS,
+ MISSING_ABI,
]
}
@@ -2944,3 +2945,28 @@ declare_lint! {
}
declare_lint_pass!(UnusedDocComment => [UNUSED_DOC_COMMENTS]);
+
+declare_lint! {
+ /// The `missing_abi` lint detects cases where the ABI is omitted from
+ /// extern declarations.
+ ///
+ /// ### Example
+ ///
+ /// ```rust,compile_fail
+ /// #![deny(missing_abi)]
+ ///
+ /// extern fn foo() {}
+ /// ```
+ ///
+ /// {{produces}}
+ ///
+ /// ### Explanation
+ ///
+ /// Historically, Rust implicitly selected C as the ABI for extern
+ /// declarations. We expect to add new ABIs, like `C-unwind`, in the future,
+ /// though this has not yet happened, and especially with their addition
+ /// seeing the ABI easily will make code review easier.
+ pub MISSING_ABI,
+ Allow,
+ "No declared ABI for extern declaration"
+}
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index 2bfc6a85576..9d60a51a0af 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -6,6 +6,7 @@ use rustc_ast::node_id::{NodeId, NodeMap};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
use rustc_span::edition::Edition;
use rustc_span::{sym, symbol::Ident, MultiSpan, Span, Symbol};
+use rustc_target::spec::abi::Abi;
pub mod builtin;
@@ -252,6 +253,7 @@ pub enum BuiltinLintDiagnostics {
UnusedImports(String, Vec<(Span, String)>),
RedundantImport(Vec<(Span, bool)>, Ident),
DeprecatedMacro(Option<Symbol>, Span),
+ MissingAbi(Span, Abi),
UnusedDocComment(Span),
PatternsInFnsWithoutBody(Span, Ident),
}