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Rollup merge of #72799 - Aaron1011:feature/span-debug, r=petrochenkov
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Add `-Z span-debug` to allow for easier debugging of proc macros

Currently, the `Debug` impl for `proc_macro::Span` just prints out
the byte range. This can make debugging proc macros (either as a crate
author or as a compiler developer) very frustrating, since neither the
actual filename nor the `SyntaxContext` is displayed.

This commit adds a perma-unstable flag `-Z span-debug`. When enabled,
the `Debug` impl for `proc_macro::Span` simply forwards directly to
`rustc_span::Span`. Once #72618 is merged, this will start displaying
actual line numbers.

While `Debug` impls are not subject to Rust's normal stability
guarnatees, we probably shouldn't expose any additional information on
stable until `#![feature(proc_macro_span)]` is stabilized. Otherwise,
we would be providing a 'backdoor' way to access information that's
supposed be behind unstable APIs.
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RalfJung authored Jun 8, 2020
2 parents 89d8979 + b541d3d commit e135087
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Showing 7 changed files with 220 additions and 1 deletion.
2 changes: 2 additions & 0 deletions src/librustc_expand/expand.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1789,6 +1789,7 @@ pub struct ExpansionConfig<'feat> {
pub trace_mac: bool,
pub should_test: bool, // If false, strip `#[test]` nodes
pub keep_macs: bool,
pub span_debug: bool, // If true, use verbose debugging for `proc_macro::Span`
}

impl<'feat> ExpansionConfig<'feat> {
Expand All @@ -1800,6 +1801,7 @@ impl<'feat> ExpansionConfig<'feat> {
trace_mac: false,
should_test: false,
keep_macs: false,
span_debug: false,
}
}

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8 changes: 7 additions & 1 deletion src/librustc_expand/proc_macro_server.rs
Original file line number Diff line number Diff line change
Expand Up @@ -352,6 +352,7 @@ pub(crate) struct Rustc<'a> {
def_site: Span,
call_site: Span,
mixed_site: Span,
span_debug: bool,
}

impl<'a> Rustc<'a> {
Expand All @@ -362,6 +363,7 @@ impl<'a> Rustc<'a> {
def_site: cx.with_def_site_ctxt(expn_data.def_site),
call_site: cx.with_call_site_ctxt(expn_data.call_site),
mixed_site: cx.with_mixed_site_ctxt(expn_data.call_site),
span_debug: cx.ecfg.span_debug,
}
}

Expand Down Expand Up @@ -646,7 +648,11 @@ impl server::Diagnostic for Rustc<'_> {

impl server::Span for Rustc<'_> {
fn debug(&mut self, span: Self::Span) -> String {
format!("{:?} bytes({}..{})", span.ctxt(), span.lo().0, span.hi().0)
if self.span_debug {
format!("{:?}", span)
} else {
format!("{:?} bytes({}..{})", span.ctxt(), span.lo().0, span.hi().0)
}
}
fn def_site(&mut self) -> Self::Span {
self.def_site
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1 change: 1 addition & 0 deletions src/librustc_interface/passes.rs
Original file line number Diff line number Diff line change
Expand Up @@ -291,6 +291,7 @@ fn configure_and_expand_inner<'a>(
recursion_limit: sess.recursion_limit(),
trace_mac: sess.opts.debugging_opts.trace_macros,
should_test: sess.opts.test,
span_debug: sess.opts.debugging_opts.span_debug,
..rustc_expand::expand::ExpansionConfig::default(crate_name.to_string())
};

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1 change: 1 addition & 0 deletions src/librustc_interface/tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -506,6 +506,7 @@ fn test_debugging_options_tracking_hash() {
untracked!(save_analysis, true);
untracked!(self_profile, SwitchWithOptPath::Enabled(None));
untracked!(self_profile_events, Some(vec![String::new()]));
untracked!(span_debug, true);
untracked!(span_free_formats, true);
untracked!(strip, Strip::None);
untracked!(terminal_width, Some(80));
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2 changes: 2 additions & 0 deletions src/librustc_session/options.rs
Original file line number Diff line number Diff line change
Expand Up @@ -996,6 +996,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
"make the current crate share its generic instantiations"),
show_span: Option<String> = (None, parse_opt_string, [TRACKED],
"show spans for compiler debugging (expr|pat|ty)"),
span_debug: bool = (false, parse_bool, [UNTRACKED],
"forward proc_macro::Span's `Debug` impl to `Span`"),
// o/w tests have closure@path
span_free_formats: bool = (false, parse_bool, [UNTRACKED],
"exclude spans when debug-printing compiler state (default: no)"),
Expand Down
41 changes: 41 additions & 0 deletions src/test/ui/proc-macro/debug/dump-debug-span-debug.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,41 @@
// run-pass
// aux-build:macro-dump-debug.rs
// compile-flags: -Z span-debug

extern crate macro_dump_debug;
use macro_dump_debug::dump_debug;

dump_debug! {
ident // ident
r#ident // raw ident
, // alone punct
==> // joint punct
() // empty group
[_] // nonempty group

// unsuffixed literals
0
1.0
"S"
b"B"
r"R"
r##"R"##
br"BR"
br##"BR"##
'C'
b'B'

// suffixed literals
0q
1.0q
"S"q
b"B"q
r"R"q
r##"R"##q
br"BR"q
br##"BR"##q
'C'q
b'B'q
}

fn main() {}
166 changes: 166 additions & 0 deletions src/test/ui/proc-macro/debug/dump-debug-span-debug.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,166 @@
TokenStream [Ident { ident: "ident", span: $DIR/dump-debug-span-debug.rs:9:5: 9:10 }, Ident { ident: "r#ident", span: $DIR/dump-debug-span-debug.rs:10:5: 10:12 }, Punct { ch: ',', spacing: Alone, span: $DIR/dump-debug-span-debug.rs:11:5: 11:6 }, Punct { ch: '=', spacing: Joint, span: $DIR/dump-debug-span-debug.rs:12:5: 12:7 }, Punct { ch: '=', spacing: Joint, span: $DIR/dump-debug-span-debug.rs:12:5: 12:7 }, Punct { ch: '>', spacing: Alone, span: $DIR/dump-debug-span-debug.rs:12:7: 12:8 }, Group { delimiter: Parenthesis, stream: TokenStream [], span: $DIR/dump-debug-span-debug.rs:13:5: 13:7 }, Group { delimiter: Bracket, stream: TokenStream [Ident { ident: "_", span: $DIR/dump-debug-span-debug.rs:14:6: 14:7 }], span: $DIR/dump-debug-span-debug.rs:14:5: 14:8 }, Literal { kind: Integer, symbol: "0", suffix: None, span: $DIR/dump-debug-span-debug.rs:17:5: 17:6 }, Literal { kind: Float, symbol: "1.0", suffix: None, span: $DIR/dump-debug-span-debug.rs:18:5: 18:8 }, Literal { kind: Str, symbol: "S", suffix: None, span: $DIR/dump-debug-span-debug.rs:19:5: 19:8 }, Literal { kind: ByteStr, symbol: "B", suffix: None, span: $DIR/dump-debug-span-debug.rs:20:5: 20:9 }, Literal { kind: StrRaw(0), symbol: "R", suffix: None, span: $DIR/dump-debug-span-debug.rs:21:5: 21:9 }, Literal { kind: StrRaw(2), symbol: "R", suffix: None, span: $DIR/dump-debug-span-debug.rs:22:5: 22:13 }, Literal { kind: ByteStrRaw(0), symbol: "BR", suffix: None, span: $DIR/dump-debug-span-debug.rs:23:5: 23:11 }, Literal { kind: ByteStrRaw(2), symbol: "BR", suffix: None, span: $DIR/dump-debug-span-debug.rs:24:5: 24:15 }, Literal { kind: Char, symbol: "C", suffix: None, span: $DIR/dump-debug-span-debug.rs:25:5: 25:8 }, Literal { kind: Byte, symbol: "B", suffix: None, span: $DIR/dump-debug-span-debug.rs:26:5: 26:9 }, Literal { kind: Integer, symbol: "0", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:29:5: 29:7 }, Literal { kind: Float, symbol: "1.0", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:30:5: 30:9 }, Literal { kind: Str, symbol: "S", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:31:5: 31:9 }, Literal { kind: ByteStr, symbol: "B", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:32:5: 32:10 }, Literal { kind: StrRaw(0), symbol: "R", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:33:5: 33:10 }, Literal { kind: StrRaw(2), symbol: "R", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:34:5: 34:14 }, Literal { kind: ByteStrRaw(0), symbol: "BR", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:35:5: 35:12 }, Literal { kind: ByteStrRaw(2), symbol: "BR", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:36:5: 36:16 }, Literal { kind: Char, symbol: "C", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:37:5: 37:9 }, Literal { kind: Byte, symbol: "B", suffix: Some("q"), span: $DIR/dump-debug-span-debug.rs:38:5: 38:10 }]
TokenStream [
Ident {
ident: "ident",
span: $DIR/dump-debug-span-debug.rs:9:5: 9:10,
},
Ident {
ident: "r#ident",
span: $DIR/dump-debug-span-debug.rs:10:5: 10:12,
},
Punct {
ch: ',',
spacing: Alone,
span: $DIR/dump-debug-span-debug.rs:11:5: 11:6,
},
Punct {
ch: '=',
spacing: Joint,
span: $DIR/dump-debug-span-debug.rs:12:5: 12:7,
},
Punct {
ch: '=',
spacing: Joint,
span: $DIR/dump-debug-span-debug.rs:12:5: 12:7,
},
Punct {
ch: '>',
spacing: Alone,
span: $DIR/dump-debug-span-debug.rs:12:7: 12:8,
},
Group {
delimiter: Parenthesis,
stream: TokenStream [],
span: $DIR/dump-debug-span-debug.rs:13:5: 13:7,
},
Group {
delimiter: Bracket,
stream: TokenStream [
Ident {
ident: "_",
span: $DIR/dump-debug-span-debug.rs:14:6: 14:7,
},
],
span: $DIR/dump-debug-span-debug.rs:14:5: 14:8,
},
Literal {
kind: Integer,
symbol: "0",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:17:5: 17:6,
},
Literal {
kind: Float,
symbol: "1.0",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:18:5: 18:8,
},
Literal {
kind: Str,
symbol: "S",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:19:5: 19:8,
},
Literal {
kind: ByteStr,
symbol: "B",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:20:5: 20:9,
},
Literal {
kind: StrRaw(0),
symbol: "R",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:21:5: 21:9,
},
Literal {
kind: StrRaw(2),
symbol: "R",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:22:5: 22:13,
},
Literal {
kind: ByteStrRaw(0),
symbol: "BR",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:23:5: 23:11,
},
Literal {
kind: ByteStrRaw(2),
symbol: "BR",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:24:5: 24:15,
},
Literal {
kind: Char,
symbol: "C",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:25:5: 25:8,
},
Literal {
kind: Byte,
symbol: "B",
suffix: None,
span: $DIR/dump-debug-span-debug.rs:26:5: 26:9,
},
Literal {
kind: Integer,
symbol: "0",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:29:5: 29:7,
},
Literal {
kind: Float,
symbol: "1.0",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:30:5: 30:9,
},
Literal {
kind: Str,
symbol: "S",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:31:5: 31:9,
},
Literal {
kind: ByteStr,
symbol: "B",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:32:5: 32:10,
},
Literal {
kind: StrRaw(0),
symbol: "R",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:33:5: 33:10,
},
Literal {
kind: StrRaw(2),
symbol: "R",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:34:5: 34:14,
},
Literal {
kind: ByteStrRaw(0),
symbol: "BR",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:35:5: 35:12,
},
Literal {
kind: ByteStrRaw(2),
symbol: "BR",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:36:5: 36:16,
},
Literal {
kind: Char,
symbol: "C",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:37:5: 37:9,
},
Literal {
kind: Byte,
symbol: "B",
suffix: Some("q"),
span: $DIR/dump-debug-span-debug.rs:38:5: 38:10,
},
]

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