Improve diagnostic deduplication

@@ -0,0 +1,63 @@+use std::hash::Hash;++use rustc_data_structures::stable_hash::StableHasher;+use rustc_serialize::Encoder;+use rustc_span::def_id::{CrateNum, DefId, DefIndex};+use rustc_span::{ByteSymbol, ExpnId, Span, SpanEncoder, Symbol, SyntaxContext};++/// Hasher used to determine if two diagnostics are the same and should be deduplicated. Used by+/// `DiagCtxtInner::emitted_diagnostics`. It's a stable hash with one special behaviour: parents of+/// spans within the diagnostics are ignored so that incremental and non-incremental compilation+/// get the same behaviour.+///+/// Although this has nothing to do with encoding data to/from file, it is implemented on top of+/// `Encoder`/`SpanEncoder` because they provide traversals of all the relevant types used within+/// diagnostics. There is no corresponding decoder.+pub(crate) struct DedupHashEncoder(pub(crate) StableHasher);++macro_rules! encoder_methods {+    ($($name:ident($ty:ty);)*) => {+        $(+            #[inline]+            fn $name(&mut self, value: $ty) {+                value.hash(&mut self.0)+            }+        )*+    }+}++impl Encoder for DedupHashEncoder {+    encoder_methods! {+        emit_usize(usize);+        emit_u128(u128);+        emit_u64(u64);+        emit_u32(u32);+        emit_u16(u16);+        emit_u8(u8);++        emit_isize(isize);+        emit_i128(i128);+        emit_i64(i64);+        emit_i32(i32);+        emit_i16(i16);++        emit_raw_bytes(&[u8]);+    }+}++impl SpanEncoder for DedupHashEncoder {+    fn encode_span(&mut self, span: Span) {+        // The raison d'être of `DedupHashEncoder` is to ignore `parent` here.+        span.with_parent(None).hash(&mut self.0);+    }++    encoder_methods! {+        encode_symbol(Symbol);+        encode_byte_symbol(ByteSymbol);+        encode_expn_id(ExpnId);+        encode_syntax_context(SyntaxContext);+        encode_crate_num(CrateNum);+        encode_def_index(DefIndex);+        encode_def_id(DefId);+    }+}

@@ -12,9 +12,11 @@ use rustc_error_messages::{DiagArgMap, DiagArgName, IntoDiagArg}; use rustc_hashes::Hash128; use rustc_lint_defs::Applicability; use rustc_macros::{Decodable, Encodable};+use rustc_serialize::Encodable; use rustc_span::{Span, Spanned, Symbol}; use tracing::debug; +use crate::dedup_hash::DedupHashEncoder; use crate::{     CodeSuggestion, DiagCtxtHandle, DiagMessage, ErrCode, ErrorGuaranteed, ExplicitBug, Level,     MultiSpan, StashKey, Style, Sublevel, Substitution, SubstitutionPart, SuggestionStyle,@@ -298,20 +300,22 @@ impl DiagInner {             emitted_at: _,   // ignore         } = self; -        let hashed_parts = (-            std::mem::discriminant(level), // ignore the field within `Warning`-            messages,-            code,-            span,-            children,-            suggestions,-            args.as_slice(),-            is_lint,-        );+        let mut e = DedupHashEncoder(StableHasher::new()); -        let mut hasher = StableHasher::new();-        hashed_parts.hash(&mut hasher);-        hasher.finish()+        // We use `discriminant` because we want to ignore the field within `Warning`.+        // `Encoder`/`SpanEncoder` can't traverse a `Discriminant<T>` so we hash it directly.+        std::mem::discriminant(level).hash(&mut e.0);++        // All the other fields are hashed via `encode`.+        messages.encode(&mut e);+        code.encode(&mut e);+        span.encode(&mut e);+        children.encode(&mut e);+        suggestions.encode(&mut e);+        args.encode(&mut e);+        is_lint.encode(&mut e);++        e.0.finish()     } } @@ -324,6 +328,16 @@ pub struct Subdiag {     pub span: MultiSpan, } +impl Subdiag {+    /// Hash used to determine if two subdiagnostics are the same. Used by+    /// `DiagCtxtInner::emitted_diagnostics`.+    pub(crate) fn dedup_hash(&self) -> Hash128 {+        let mut e = DedupHashEncoder(StableHasher::new());+        self.encode(&mut e);+        e.0.finish()+    }+}+ /// Used for emitting structured error messages and other diagnostic information. /// Wraps a `DiagInner`, adding some useful things. /// - The `dcx` field, allowing it to (a) emit itself, and (b) do a drop check

@@ -44,7 +44,6 @@ use emitter::{DynEmitter, Emitter}; use rustc_ast::attr::version::RustcVersion; use rustc_data_structures::AtomicRef; use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};-use rustc_data_structures::stable_hash::StableHasher; use rustc_data_structures::sync::{DynSend, Lock}; pub use rustc_error_messages::{     DiagArg, DiagArgFromDisplay, DiagArgMap, DiagArgName, DiagArgValue, DiagMessage, IntoDiagArg,@@ -70,6 +69,7 @@ use crate::timings::TimingRecord; pub mod annotate_snippet_emitter_writer; pub mod codes; mod decorate_diag;+mod dedup_hash; mod diagnostic; mod diagnostic_impls; pub mod emitter;@@ -1321,21 +1321,18 @@ impl DiagCtxtInner {                 debug!(?diagnostic);                 debug!(?self.emitted_diagnostics); -                let not_yet_emitted = |sub: &mut Subdiag| {+                let show_sub = |sub: &Subdiag| {                     debug!(?sub);                     match sub.level {                         Sublevel::Error | Sublevel::Warning | Sublevel::Note | Sublevel::Help => {-                            return true;+                            true+                        }+                        Sublevel::OnceNote | Sublevel::OnceHelp => {+                            self.emitted_diagnostics.insert(sub.dedup_hash())                         }-                        Sublevel::OnceNote | Sublevel::OnceHelp => {}                     }-                    let mut hasher = StableHasher::new();-                    sub.hash(&mut hasher);-                    let diagnostic_hash = hasher.finish();-                    debug!(?diagnostic_hash);-                    self.emitted_diagnostics.insert(diagnostic_hash)                 };-                diagnostic.children.retain_mut(not_yet_emitted);+                diagnostic.children.retain(show_sub);                 if already_emitted {                     let msg = "duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`";                     diagnostic.sub(Sublevel::Note, msg, MultiSpan::new());

@@ -929,10 +929,12 @@ impl<'tcx> TyEncoder<'tcx> for CacheEncoder<'tcx> {  macro_rules! encoder_methods {     ($($name:ident($ty:ty);)*) => {-        #[inline]-        $(fn $name(&mut self, value: $ty) {-            self.encoder.$name(value)-        })*+        $(+            #[inline]+            fn $name(&mut self, value: $ty) {+                self.encoder.$name(value)+            }+        )*     } } 

@@ -0,0 +1,15 @@+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`++error: aborting due to 1 previous error++For more information about this error, try `rustc --explain E0277`.

@@ -0,0 +1,54 @@+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`++error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`++error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`++error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`++error: aborting due to 4 previous errors++For more information about this error, try `rustc --explain E0277`.

@@ -0,0 +1,15 @@+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`++error: aborting due to 1 previous error++For more information about this error, try `rustc --explain E0277`.

@@ -0,0 +1,54 @@+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`++error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`++error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`++error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied+  --> $DIR/deduplicate-diagnostics-incr.rs:11:11+   |+LL | #[global_allocator]+   | ------------------- in this attribute macro expansion+LL | static A: usize = 0;+   |           ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize`+   |+help: the trait `GlobalAllocator` is implemented for `System`+  --> $SRC_DIR/std/src/alloc.rs:LL:COL+   = note: required for `usize` to implement `GlobalAlloc`+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`++error: aborting due to 4 previous errors++For more information about this error, try `rustc --explain E0277`.

@@ -0,0 +1,17 @@+//! Test that span parents (which are incremental only) are ignored when deduplicating diagnostics.+//! Regression test for #162901.++//@ revisions: dedup dup incr-dedup incr-dup+//@[dedup] compile-flags: -Z deduplicate-diagnostics=yes+//@[incr-dup] incremental+//@[incr-dedup] incremental+//@[incr-dedup] compile-flags: -Z deduplicate-diagnostics=yes++#[global_allocator]+static A: usize = 0;+//[dedup,dup,incr-dedup,incr-dup]~^ ERROR E0277+//[dup,incr-dup]~| ERROR E0277+//[dup,incr-dup]~| ERROR E0277+//[dup,incr-dup]~| ERROR E0277++fn main() {}

@@ -35,6 +35,7 @@ numer = "numer" # short for numerator, not a typo for "number" old-skool = "old-skool" # variant spelling of "old-school" optin = "optin" # short for opt-in publically = "publically"+raison = "raison" # part of the French phrase "raison d'être" rplace = "rplace" # short for R-place splitted = "splitted" sythetic = "sythetic" # typo in vendored LLVM sources