rust/src/test/ui/proc-macro/nonterminal-token-hygiene.stdout

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PRINT-BANG INPUT (DISPLAY): struct S;
PRINT-BANG RE-COLLECTED (DISPLAY): struct S ;
PRINT-BANG INPUT (DEBUG): TokenStream [
Group {
delimiter: None,
stream: TokenStream [
Ident {
ident: "struct",
span: $DIR/nonterminal-token-hygiene.rs:30:5: 30:11 (#5),
},
Ident {
ident: "S",
span: $DIR/nonterminal-token-hygiene.rs:30:12: 30:13 (#5),
},
Punct {
ch: ';',
spacing: Alone,
span: $DIR/nonterminal-token-hygiene.rs:30:13: 30:14 (#5),
},
],
span: $DIR/nonterminal-token-hygiene.rs:20:27: 20:32 (#6),
},
]
#![feature /* 0#0 */(prelude_import)]
#![no_std /* 0#0 */]
// Make sure that marks from declarative macros are applied to tokens in nonterminal.
// check-pass
// compile-flags: -Z span-debug -Z macro-backtrace -Z unpretty=expanded,hygiene
// compile-flags: -Z trim-diagnostic-paths=no
// normalize-stdout-test "\d+#" -> "0#"
// aux-build:test-macros.rs
#![feature /* 0#0 */(decl_macro)]
#![no_std /* 0#0 */]
#[prelude_import /* 0#1 */]
use ::core /* 0#1 */::prelude /* 0#1 */::rust_2015 /* 0#1 */::*;
#[macro_use /* 0#1 */]
extern crate core /* 0#2 */;
#[macro_use /* 0#1 */]
extern crate compiler_builtins /* 0#2 */;
// Don't load unnecessary hygiene information from std
extern crate std /* 0#0 */;
#[macro_use /* 0#0 */]
extern crate test_macros /* 0#0 */;
macro_rules! outer
/*
0#0
*/ {
($ item : item) =>
{
macro inner() { print_bang! { $ item } } inner! () ;
} ;
}
struct S /* 0#0 */;
macro inner /* 0#4 */ { () => { print_bang! { struct S; } } }
struct S /* 0#5 */;
// OK, not a duplicate definition of `S`
fn main /* 0#0 */() { }
/*
Expansions:
0: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Root
1: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: AstPass(StdImports)
Implement span quoting for proc-macros This PR implements span quoting, allowing proc-macros to produce spans pointing *into their own crate*. This is used by the unstable `proc_macro::quote!` macro, allowing us to get error messages like this: ``` error[E0412]: cannot find type `MissingType` in this scope --> $DIR/auxiliary/span-from-proc-macro.rs:37:20 | LL | pub fn error_from_attribute(_args: TokenStream, _input: TokenStream) -> TokenStream { | ----------------------------------------------------------------------------------- in this expansion of procedural macro `#[error_from_attribute]` ... LL | field: MissingType | ^^^^^^^^^^^ not found in this scope | ::: $DIR/span-from-proc-macro.rs:8:1 | LL | #[error_from_attribute] | ----------------------- in this macro invocation ``` Here, `MissingType` occurs inside the implementation of the proc-macro `#[error_from_attribute]`. Previosuly, this would always result in a span pointing at `#[error_from_attribute]` This will make many proc-macro-related error message much more useful - when a proc-macro generates code containing an error, users will get an error message pointing directly at that code (within the macro definition), instead of always getting a span pointing at the macro invocation site. This is implemented as follows: * When a proc-macro crate is being *compiled*, it causes the `quote!` macro to get run. This saves all of the sapns in the input to `quote!` into the metadata of *the proc-macro-crate* (which we are currently compiling). The `quote!` macro then expands to a call to `proc_macro::Span::recover_proc_macro_span(id)`, where `id` is an opaque identifier for the span in the crate metadata. * When the same proc-macro crate is *run* (e.g. it is loaded from disk and invoked by some consumer crate), the call to `proc_macro::Span::recover_proc_macro_span` causes us to load the span from the proc-macro crate's metadata. The proc-macro then produces a `TokenStream` containing a `Span` pointing into the proc-macro crate itself. The recursive nature of 'quote!' can be difficult to understand at first. The file `src/test/ui/proc-macro/quote-debug.stdout` shows the output of the `quote!` macro, which should make this eaier to understand. This PR also supports custom quoting spans in custom quote macros (e.g. the `quote` crate). All span quoting goes through the `proc_macro::quote_span` method, which can be called by a custom quote macro to perform span quoting. An example of this usage is provided in `src/test/ui/proc-macro/auxiliary/custom-quote.rs` Custom quoting currently has a few limitations: In order to quote a span, we need to generate a call to `proc_macro::Span::recover_proc_macro_span`. However, proc-macros support renaming the `proc_macro` crate, so we can't simply hardcode this path. Previously, the `quote_span` method used the path `crate::Span` - however, this only works when it is called by the builtin `quote!` macro in the same crate. To support being called from arbitrary crates, we need access to the name of the `proc_macro` crate to generate a path. This PR adds an additional argument to `quote_span` to specify the name of the `proc_macro` crate. Howver, this feels kind of hacky, and we may want to change this before stabilizing anything quote-related. Additionally, using `quote_span` currently requires enabling the `proc_macro_internals` feature. The builtin `quote!` macro has an `#[allow_internal_unstable]` attribute, but this won't work for custom quote implementations. This will likely require some additional tricks to apply `allow_internal_unstable` to the span of `proc_macro::Span::recover_proc_macro_span`.
2020-08-02 23:52:16 +00:00
2: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Macro { kind: Bang, name: "outer", proc_macro: false }
3: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: AstPass(StdImports)
Implement span quoting for proc-macros This PR implements span quoting, allowing proc-macros to produce spans pointing *into their own crate*. This is used by the unstable `proc_macro::quote!` macro, allowing us to get error messages like this: ``` error[E0412]: cannot find type `MissingType` in this scope --> $DIR/auxiliary/span-from-proc-macro.rs:37:20 | LL | pub fn error_from_attribute(_args: TokenStream, _input: TokenStream) -> TokenStream { | ----------------------------------------------------------------------------------- in this expansion of procedural macro `#[error_from_attribute]` ... LL | field: MissingType | ^^^^^^^^^^^ not found in this scope | ::: $DIR/span-from-proc-macro.rs:8:1 | LL | #[error_from_attribute] | ----------------------- in this macro invocation ``` Here, `MissingType` occurs inside the implementation of the proc-macro `#[error_from_attribute]`. Previosuly, this would always result in a span pointing at `#[error_from_attribute]` This will make many proc-macro-related error message much more useful - when a proc-macro generates code containing an error, users will get an error message pointing directly at that code (within the macro definition), instead of always getting a span pointing at the macro invocation site. This is implemented as follows: * When a proc-macro crate is being *compiled*, it causes the `quote!` macro to get run. This saves all of the sapns in the input to `quote!` into the metadata of *the proc-macro-crate* (which we are currently compiling). The `quote!` macro then expands to a call to `proc_macro::Span::recover_proc_macro_span(id)`, where `id` is an opaque identifier for the span in the crate metadata. * When the same proc-macro crate is *run* (e.g. it is loaded from disk and invoked by some consumer crate), the call to `proc_macro::Span::recover_proc_macro_span` causes us to load the span from the proc-macro crate's metadata. The proc-macro then produces a `TokenStream` containing a `Span` pointing into the proc-macro crate itself. The recursive nature of 'quote!' can be difficult to understand at first. The file `src/test/ui/proc-macro/quote-debug.stdout` shows the output of the `quote!` macro, which should make this eaier to understand. This PR also supports custom quoting spans in custom quote macros (e.g. the `quote` crate). All span quoting goes through the `proc_macro::quote_span` method, which can be called by a custom quote macro to perform span quoting. An example of this usage is provided in `src/test/ui/proc-macro/auxiliary/custom-quote.rs` Custom quoting currently has a few limitations: In order to quote a span, we need to generate a call to `proc_macro::Span::recover_proc_macro_span`. However, proc-macros support renaming the `proc_macro` crate, so we can't simply hardcode this path. Previously, the `quote_span` method used the path `crate::Span` - however, this only works when it is called by the builtin `quote!` macro in the same crate. To support being called from arbitrary crates, we need access to the name of the `proc_macro` crate to generate a path. This PR adds an additional argument to `quote_span` to specify the name of the `proc_macro` crate. Howver, this feels kind of hacky, and we may want to change this before stabilizing anything quote-related. Additionally, using `quote_span` currently requires enabling the `proc_macro_internals` feature. The builtin `quote!` macro has an `#[allow_internal_unstable]` attribute, but this won't work for custom quote implementations. This will likely require some additional tricks to apply `allow_internal_unstable` to the span of `proc_macro::Span::recover_proc_macro_span`.
2020-08-02 23:52:16 +00:00
4: parent: ExpnId(2), call_site_ctxt: #4, def_site_ctxt: #4, kind: Macro { kind: Bang, name: "inner", proc_macro: false }
5: parent: ExpnId(4), call_site_ctxt: #6, def_site_ctxt: #0, kind: Macro { kind: Bang, name: "print_bang", proc_macro: true }
SyntaxContexts:
#0: parent: #0, outer_mark: (ExpnId(0), Opaque)
#1: parent: #0, outer_mark: (ExpnId(1), Opaque)
#2: parent: #0, outer_mark: (ExpnId(1), Transparent)
#3: parent: #0, outer_mark: (ExpnId(3), Opaque)
#4: parent: #0, outer_mark: (ExpnId(2), SemiTransparent)
#5: parent: #0, outer_mark: (ExpnId(4), Opaque)
#6: parent: #4, outer_mark: (ExpnId(4), Opaque)
#7: parent: #0, outer_mark: (ExpnId(5), Opaque)
#8: parent: #6, outer_mark: (ExpnId(5), Transparent)
#9: parent: #5, outer_mark: (ExpnId(5), SemiTransparent)
*/