Implement function-like procedural macros ( `#[proc_macro]`) #40129

abonander · 2017-02-27T20:11:28Z

Adds the #[proc_macro] attribute, which expects bare functions of the kind fn(TokenStream) -> TokenStream, which can be invoked like my_macro!().

cc rust-lang/rfcs#1913, #38356

r? @jseyfried
cc @nrc

abonander · 2017-02-27T20:13:09Z

Unanswered question: did we decide whether or not to include the outer delimiters from the invocation in the input? i.e. rewrite!("Hello, world!") would see "( \"Hello, world!\" )" I forget.

abonander · 2017-02-27T20:13:42Z

src/libsyntax_ext/proc_macro_registrar.rs

    function_name: Ident,
    span: Span,
 }

 struct CollectProcMacros<'a> {
    derives: Vec<ProcMacroDerive>,
-    attr_macros: Vec<AttrProcMacro>,
+    attr_macros: Vec<ProcMacroDef>,
+    bang_macros: Vec<ProcMacroDef>,


I'm on the fence about reusing the typedef. I didn't see much point to having a unique type with the same signature.

This looks good as is.

abonander · 2017-02-27T20:14:50Z

src/test/run-pass-fulldeps/proc-macro/auxiliary/bang-macro.rs

+pub fn rewrite(input: TokenStream) -> TokenStream {
+    let input = input.to_string();
+
+    assert_eq!(input, r#""Hello, world!""#);


This might fail the test because the wrapping delimiters might get included. I forget what the executive decision was on whether or not to include those.

Nope, works as-is.

abonander · 2017-02-27T23:22:40Z

<jseyfried> DroidLogician: We decided not to include the wrapping () / [] / {} for now

Looks like I didn't have to do any extra work to support that as-is, very nice.

abonander · 2017-02-27T23:25:28Z

src/libsyntax_ext/proc_macro_registrar.rs

@@ -232,7 +257,8 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
        let mut found_attr: Option<&'a ast::Attribute> = None;

        for attr in &item.attrs {
-            if attr.check_name("proc_macro_derive") || attr.check_name("proc_macro_attribute") {
+            if attr.check_name("proc_macro_derive") || attr.check_name("proc_macro_attribute") ||
+                attr.check_name("proc_macro") {


Formatting suggestion welcome here.

Should be indented three spaces (to align with first condition) or eight spaces (to distinguish from body).

Eh, I don't really like how either of those look so it's your call. I would almost prefer a .check_names() method which can take a slice or iterator or something.

In this case I'd write:

if PROC_MACRO_KINDS.iter().any(|kind| attr.check_name(kind)) { ... }

where

const PROC_MACRO_KINDS: [&'static str, 3] = ["proc_macro", "proc_macro_attribute", "proc_macro_derive"];

Sounds good. I might use the static-in-const feature to make that a little shorter too.

abonander · 2017-02-27T23:26:34Z

src/libproc_macro/lib.rs

@@ -125,6 +125,10 @@ pub mod __internal {
        fn register_attr_proc_macro(&mut self,
                                    name: &str,
                                    expand: fn(TokenStream, TokenStream) -> TokenStream);
+
+        fn register_bang_proc_macro(&mut self,


Bikeshed: "fnlike" instead of "bang"?

I prefer Bang inside the compiler to avoid overloading "function". Also, we might want to use "proc macro function" for the underlying function item annotated with #[proc_macro*].

Also, we might want to use "proc macro function" for the underlying function item annotated with #[proc_macro*].

Clarify?

For #[proc_macro_derive(A)] fn f(..) { .. }, we would say A is a [derive] proc macro and f is the [derive] proc macro function.

Okay. That doesn't affect anything in this PR, though, right? That's purely wording for documentation and stuff?

Yeah, it's just an argument for "bang proc macro" instead of "function / fnlike procedural macro".

jseyfried · 2017-02-28T02:52:13Z

src/libsyntax/feature_gate.rs

+    ("proc_macro", Normal, Gated(Stability::Unstable,
+                                           "proc_macro",
+                                           "function-like proc macros are currently unstable",
+                                           cfg_fn!(proc_macro))),


nit: These should be indented to the same column as Stability::Unstable,.

jseyfried · 2017-02-28T02:53:02Z

src/libsyntax_ext/proc_macro_impl.rs

+                }
+                if let Some(s) = e.downcast_ref::<&'static str>() {
+                    err.help(&format!("message: {}", s));
+                }


It would be nice to factor this out to avoid duplication across macro kinds (not needed for this PR though).

jseyfried · 2017-02-28T02:53:52Z

src/libsyntax_ext/proc_macro_registrar.rs

@@ -27,21 +27,25 @@ use syntax_pos::{Span, DUMMY_SP};

 use deriving;

+const PROC_MACRO_KINDS: [&'static str; 3] = ["proc_macro_derive", "proc_macro_attribute",
+                                             "proc_macro"];


nit: I would break after the = or give each macro kind its own line.

jseyfried · 2017-02-28T02:54:23Z

src/libsyntax_ext/proc_macro_registrar.rs

    function_name: Ident,
    span: Span,
 }

 struct CollectProcMacros<'a> {
    derives: Vec<ProcMacroDerive>,
-    attr_macros: Vec<AttrProcMacro>,
+    attr_macros: Vec<ProcMacroDef>,
+    bang_macros: Vec<ProcMacroDef>,


This looks good as is.

jseyfried · 2017-02-28T03:02:32Z

@abonander Looks great!

What happens when we #[macro_use] a bang procedural macro? I think this should behave the same as #[macro_use]ing an attribute procedural macro (i.e. error when the #[macro_use] import is used and suggest a use import instead).

cc @keeperofdakeys

abonander · 2017-02-28T03:14:32Z

I'll have to test that, I think we're only checking that in the attribute proc macro codepath.

keeperofdakeys · 2017-02-28T04:18:04Z

Only supporting use seems like the best thing.

@abonander Nice. Maybe you'd like to add a misspelled call for a proc macro to this test, so we can test suggestions? They should be working, but it would be good to make sure.

abonander · 2017-02-28T04:25:53Z

Yeah #[macro_use] is currently importing bang proc macros without a problem so I'll fix that real quick. Don't give me any hints, I want to see if I can figure it out myself since I've already been digging around in resolve.

jseyfried · 2017-02-28T05:08:08Z

src/test/run-pass-fulldeps/proc-macro/bang-macro.rs

+
+// aux-build:bang-macro.rs
+
+#![allow(warnings)]


Why do we need this?

We don't. I copy-pasted this from another file to get the copyright and stuff and I must have forgotten to remove that.

keeperofdakeys · 2017-02-28T05:14:04Z

@abonander Awesome, thanks.

abonander · 2017-02-28T07:44:18Z

@jseyfried Last nits fixed and rebased.

jseyfried · 2017-03-01T02:23:58Z

src/libsyntax_ext/proc_macro_registrar.rs

+    fn collect_bang_proc_macro(&mut self, item: &'a ast::Item, attr: &'a ast::Attribute) {
+        if let Some(_) = attr.meta_item_list() {
+            self.handler.span_err(attr.span, "`#[proc_macro]` attribute
+                cannot contain any meta items");


"meta item" is compiler jargon -- I'd say "does not accept arguments" (also applies to proc_macro_attribute).

jseyfried · 2017-03-01T02:27:07Z

src/test/compile-fail-fulldeps/proc-macro/macro-use-bang.rs

+fn main() {
+    bang_proc_macro!(println!("Hello, world!"));
+    //~^ ERROR: procedural macros cannot be imported with `#[macro_use]`
+}


nit: trailing newline

jseyfried · 2017-03-01T02:28:35Z

r=me modulo comments
@bors delegate=abonander

bors · 2017-03-01T02:28:36Z

✌️ @abonander can now approve this pull request

abonander · 2017-03-01T02:35:28Z

@bors r=jseyfried

bors · 2017-03-01T02:35:29Z

📌 Commit 2fcbb48 has been approved by jseyfried

@jseyfried

Implement function-like procedural macros ( `#[proc_macro]`) Adds the `#[proc_macro]` attribute, which expects bare functions of the kind `fn(TokenStream) -> TokenStream`, which can be invoked like `my_macro!()`. cc rust-lang/rfcs#1913, rust-lang#38356 r? @jseyfried cc @nrc

@jseyfried

Implement function-like procedural macros ( `#[proc_macro]`) Adds the `#[proc_macro]` attribute, which expects bare functions of the kind `fn(TokenStream) -> TokenStream`, which can be invoked like `my_macro!()`. cc rust-lang/rfcs#1913, rust-lang#38356 r? @jseyfried cc @nrc

@jseyfried

Implement function-like procedural macros ( `#[proc_macro]`) Adds the `#[proc_macro]` attribute, which expects bare functions of the kind `fn(TokenStream) -> TokenStream`, which can be invoked like `my_macro!()`. cc rust-lang/rfcs#1913, rust-lang#38356 r? @jseyfried cc @nrc

Rollup of 7 pull requests - Successful merges: #39832, #40104, #40110, #40117, #40129, #40139, #40166 - Failed merges:

rust-lang/rust#40129

rust-highfive assigned jseyfried Feb 27, 2017

abonander commented Feb 27, 2017

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abonander changed the title ~~[WIP?] Implement function-like procedural macros ( #[proc_macro])~~ Implement function-like procedural macros ( #[proc_macro]) Feb 27, 2017

abonander force-pushed the proc_macro_bang branch from bdbadad to fcebcf4 Compare February 27, 2017 23:21

abonander commented Feb 27, 2017

View reviewed changes

abonander force-pushed the proc_macro_bang branch 3 times, most recently from c7035cb to e7f258e Compare February 28, 2017 01:40

jseyfried reviewed Feb 28, 2017

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jseyfried mentioned this pull request Feb 28, 2017

Tracking issue for RFC 1566: Procedural macros #38356

Closed

31 tasks

abonander force-pushed the proc_macro_bang branch from 489cd50 to 1be0a59 Compare February 28, 2017 07:44

jseyfried reviewed Mar 1, 2017

View reviewed changes

Implement function-like procedural macros ( #[proc_macro])

2fcbb48

abonander force-pushed the proc_macro_bang branch from 1be0a59 to 2fcbb48 Compare March 1, 2017 02:34

frewsxcv mentioned this pull request Mar 2, 2017

Rollup of 6 pull requests #40211

Closed

frewsxcv mentioned this pull request Mar 2, 2017

Rollup of 7 pull requests #40215

Closed

frewsxcv mentioned this pull request Mar 2, 2017

Rollup of 7 pull requests #40216

Merged

bors added a commit that referenced this pull request Mar 2, 2017

Auto merge of #40216 - frewsxcv:rollup, r=frewsxcv

c0b7112

Rollup of 7 pull requests - Successful merges: #39832, #40104, #40110, #40117, #40129, #40139, #40166 - Failed merges:

bors merged commit 2fcbb48 into rust-lang:master Mar 2, 2017

chpio added a commit to vtree-rs/vtree that referenced this pull request Mar 9, 2017

convert proc macro to "#[proc_macro]"/"proc macros 1.2"

72a9b51

rust-lang/rust#40129

cuviper mentioned this pull request Jun 1, 2017

rustbuild: Add ./x.py test --no-fail-fast #42363

Merged


		// aux-build:bang-macro.rs

		#![allow(warnings)]

Implement function-like procedural macros ( #[proc_macro]) #40129

Implement function-like procedural macros ( #[proc_macro]) #40129

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jseyfried commented Feb 28, 2017

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jseyfried commented Mar 1, 2017

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bors commented Mar 1, 2017

Implement function-like procedural macros ( `#[proc_macro]`) #40129

Implement function-like procedural macros ( `#[proc_macro]`) #40129

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