2020-11-05 21:36:30 +00:00
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PRINT-BANG INPUT (DISPLAY): struct S;
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PRINT-BANG RE-COLLECTED (DISPLAY): struct S ;
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PRINT-BANG INPUT (DEBUG): TokenStream [
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Group {
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delimiter: None,
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stream: TokenStream [
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Ident {
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ident: "struct",
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span: $DIR/nonterminal-token-hygiene.rs:30:5: 30:11 (#5),
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},
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Ident {
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ident: "S",
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span: $DIR/nonterminal-token-hygiene.rs:30:12: 30:13 (#5),
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},
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Punct {
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ch: ';',
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spacing: Alone,
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span: $DIR/nonterminal-token-hygiene.rs:30:13: 30:14 (#5),
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},
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],
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span: $DIR/nonterminal-token-hygiene.rs:20:27: 20:32 (#6),
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},
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]
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#![feature /* 0#0 */(prelude_import)]
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#![no_std /* 0#0 */]
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// Make sure that marks from declarative macros are applied to tokens in nonterminal.
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// check-pass
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// compile-flags: -Z span-debug -Z macro-backtrace -Z unpretty=expanded,hygiene
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// compile-flags: -Z trim-diagnostic-paths=no
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// normalize-stdout-test "\d+#" -> "0#"
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// aux-build:test-macros.rs
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#![feature /* 0#0 */(decl_macro)]
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#![no_std /* 0#0 */]
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#[prelude_import /* 0#1 */]
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2021-02-17 14:52:31 +00:00
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use ::core /* 0#1 */::prelude /* 0#1 */::rust_2015 /* 0#1 */::*;
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2020-11-05 21:36:30 +00:00
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#[macro_use /* 0#1 */]
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extern crate core /* 0#2 */;
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#[macro_use /* 0#1 */]
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extern crate compiler_builtins /* 0#2 */;
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// Don't load unnecessary hygiene information from std
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extern crate std /* 0#0 */;
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#[macro_use /* 0#0 */]
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extern crate test_macros /* 0#0 */;
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macro_rules! outer
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/*
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0#0
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*/ {
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($ item : item) =>
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{
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2021-05-01 19:54:47 +00:00
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macro inner() { print_bang! { $ item } } inner! () ;
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2020-11-05 21:36:30 +00:00
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} ;
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}
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struct S /* 0#0 */;
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2021-05-01 19:54:47 +00:00
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macro inner /* 0#4 */ { () => { print_bang! { struct S; } } }
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2020-11-05 21:36:30 +00:00
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struct S /* 0#5 */;
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// OK, not a duplicate definition of `S`
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fn main /* 0#0 */() { }
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/*
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Expansions:
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0: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Root
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1: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: AstPass(StdImports)
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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
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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
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::: $DIR/span-from-proc-macro.rs:8:1
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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
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2: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Macro { kind: Bang, name: "outer", proc_macro: false }
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2020-11-05 21:36:30 +00:00
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3: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: AstPass(StdImports)
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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
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4: parent: ExpnId(2), call_site_ctxt: #4, def_site_ctxt: #4, kind: Macro { kind: Bang, name: "inner", proc_macro: false }
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5: parent: ExpnId(4), call_site_ctxt: #6, def_site_ctxt: #0, kind: Macro { kind: Bang, name: "print_bang", proc_macro: true }
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2020-11-05 21:36:30 +00:00
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SyntaxContexts:
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#0: parent: #0, outer_mark: (ExpnId(0), Opaque)
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#1: parent: #0, outer_mark: (ExpnId(1), Opaque)
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#2: parent: #0, outer_mark: (ExpnId(1), Transparent)
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#3: parent: #0, outer_mark: (ExpnId(3), Opaque)
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#4: parent: #0, outer_mark: (ExpnId(2), SemiTransparent)
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#5: parent: #0, outer_mark: (ExpnId(4), Opaque)
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#6: parent: #4, outer_mark: (ExpnId(4), Opaque)
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#7: parent: #0, outer_mark: (ExpnId(5), Opaque)
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#8: parent: #6, outer_mark: (ExpnId(5), Transparent)
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#9: parent: #5, outer_mark: (ExpnId(5), SemiTransparent)
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*/
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