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remove extraneous semicolons from macro expansions, fix span for unex…
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…pected format specifier error
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@ct-austin
ct-austin committed Sep 9, 2020
1 parent 7b6e821 commit 5eb7b6b
Showing 1 changed file with 22 additions and 15 deletions.
37 changes: 22 additions & 15 deletions impl/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,8 @@ extern crate lazy_static;
extern crate quote;
use proc_macro_hack::proc_macro_hack;
use regex::Regex;
use syn::Token;
use syn::{Token, Error};
use syn::export::Span;

fn consume_expr(s: &str) -> (&str, String) {
lazy_static! {
Expand Down Expand Up @@ -88,7 +89,7 @@ macro_rules! def_ifmt_macro {
use syn::parse_macro_input;
let FormatContents{fmt, args} = parse_macro_input!(tokens as FormatContents);
(quote! {
::std::$to_wrap!(#fmt, #(#args),*);
::std::$to_wrap!(#fmt, #(#args),*)
}).into()
}
}
Expand All @@ -112,7 +113,7 @@ struct FormatSpec {
spec: String,
}

fn parse_format_type(id: &str, input: syn::parse::ParseStream) -> syn::parse::Result<String> {
fn parse_format_type(id: &str, span: Span, input: syn::parse::ParseStream) -> syn::parse::Result<String> {
let mut out = String::new();
if id == "x" || id == "X" {
out.push_str(&id);
Expand All @@ -127,8 +128,7 @@ fn parse_format_type(id: &str, input: syn::parse::ParseStream) -> syn::parse::Re
} else if id == "S" {
out.push('E');
} else {
// TODO this gives "unexpected end of expression" alongside the intended error
return Err(input.error(format!("{} is not a valid format type", id)));
return Err(Error::new(span, format!("{} is not a valid format type", id)));
}
Ok(out)
}
Expand All @@ -138,6 +138,8 @@ fn parse_precision_type(input: syn::parse::ParseStream) -> syn::parse::Result<St
// TODO make it so these can be identifiers/exprs as well? maybe in parens?
let mut spec = String::new();

let span = input.cursor().span();

// ['.']
if input.peek(Token![.]) {
input.parse::<Token![.]>()?;
Expand All @@ -148,7 +150,7 @@ fn parse_precision_type(input: syn::parse::ParseStream) -> syn::parse::Result<St
if lit.suffix() != "" {
spec.push_str(&lit_str[..lit_str.len() - lit.suffix().len()]);
// [type]
spec.push_str(&parse_format_type(&lit.suffix(), input)?);
spec.push_str(&parse_format_type(&lit.suffix(), span, input)?);
} else {
spec.push_str(&lit_str);
}
Expand All @@ -161,7 +163,7 @@ fn parse_precision_type(input: syn::parse::ParseStream) -> syn::parse::Result<St
// [type]
} else if input.peek(syn::Ident) {
let id = input.parse::<syn::Ident>()?.to_string();
spec.push_str(&parse_format_type(&id, input)?);
spec.push_str(&parse_format_type(&id, span, input)?);
}

Ok(spec)
Expand Down Expand Up @@ -233,30 +235,32 @@ impl syn::parse::Parse for FormatSpec {
// ['0'][width]['.' precision][type]
if input.peek(syn::LitFloat) {
// ['0'][width]['.' precision][type]
let span = input.cursor().span();
let lit = input.parse::<syn::LitFloat>()?;
let lit_str = lit.to_string();
if lit.suffix() != "" {
// ['0'][width]['.' precision]
spec.push_str(&lit_str[..lit_str.len()-lit.suffix().len()]);
// [type]
spec.push_str(&parse_format_type(&lit.suffix(), input)?);
spec.push_str(&parse_format_type(&lit.suffix(), span, input)?);
} else {
// ['0'][width]['.' precision]
spec.push_str(&lit_str);
// [type]
if input.peek(syn::Ident) {
let id = input.parse::<syn::Ident>()?.to_string();
spec.push_str(&parse_format_type(&id, input)?);
spec.push_str(&parse_format_type(&id, span, input)?);
}
}
} else if input.peek(syn::LitInt) {
// ['0'][width][type]
let span = input.cursor().span();
let lit = input.parse::<syn::LitInt>()?;
let lit_str = lit.to_string();
if lit.suffix() != "" {
spec.push_str(&lit_str[..lit_str.len()-lit.suffix().len()]);
// [type]
spec.push_str(&parse_format_type(&lit.suffix(), input)?);
spec.push_str(&parse_format_type(&lit.suffix(), span, input)?);
} else {
// ['.' precision][type]
spec.push_str(&lit_str);
Expand Down Expand Up @@ -342,9 +346,12 @@ impl FormatContents {
fmt += &ls.value().replace("{", "{{").replace("}", "}}");
expect_expr = true;
} else if expect_expr {
// TODO: expression parsing spans don't work as expected for unexpected end errors
// e.g. iprintln!("test" 1 +); will have an error pointing at "test"
// however, iprintln!("test" 1 + (2 +)); works fine
// Bug in proc_macro_hack(fake_call_site): iformat!("x:" 2 + );'s
// "unexpected end of input" error span points at the first token in the macro
// invocation rather than the end.
// not going to try to work around - probably not a common mistake and
// if proc_macro_hack becomes a pass-through as mentioned by dtolnay
// (or, barring that, if I remove it as a dependency) the issue goes away
let expr = input.parse::<syn::Expr>()?;
args.push(expr);
fmt.push_str("{");
Expand Down Expand Up @@ -401,7 +408,7 @@ pub fn iwrite(tokens: proc_macro::TokenStream) -> proc_macro::TokenStream {
use syn::parse_macro_input;
let WriteFormat{buf, fmt_contents: FormatContents{fmt, args}} = parse_macro_input!(tokens as WriteFormat);
(quote! {
::std::write!(#buf, #fmt, #(#args),*);
::std::write!(#buf, #fmt, #(#args),*)
}).into()
}

Expand All @@ -410,6 +417,6 @@ pub fn iwriteln(tokens: proc_macro::TokenStream) -> proc_macro::TokenStream {
use syn::parse_macro_input;
let WriteFormat{buf, fmt_contents: FormatContents{fmt, args}} = parse_macro_input!(tokens as WriteFormat);
(quote! {
::std::writeln!(#buf, #fmt, #(#args),*);
::std::writeln!(#buf, #fmt, #(#args),*)
}).into()
}

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