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Recover from parse errors in struct literal fields

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Attempt to recover from parse errors while parsing a struct's literal fields
by skipping tokens until a comma or the closing brace is found. This allows
errors in other fields to be reported.
This commit is contained in:
Esteban Küber 2019-01-20 00:37:06 -08:00
parent 0c0c585281
commit b1f169fe7a
7 changed files with 132 additions and 15 deletions
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47
src/libsyntax/parse/parser.rs
View File

@ -100,6 +100,7 @@ pub enum PathStyle {
enum SemiColonMode {
Break,
Ignore,
Comma,
}
#[derive(Clone, Copy, PartialEq, Debug)]
@ -2656,18 +2657,37 @@ fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Att
break;
}
let mut recovery_field = None;
if let token::Ident(ident, _) = self.token {
if !self.token.is_reserved_ident() {
let mut ident = ident.clone();
ident.span = self.span;
recovery_field = Some(ast::Field {
ident,
span: self.span,
expr: self.mk_expr(self.span, ExprKind::Err, ThinVec::new()),
is_shorthand: true,
attrs: ThinVec::new(),
});
}
}
match self.parse_field() {
Ok(f) => fields.push(f),
Err(mut e) => {
e.span_label(struct_sp, "while parsing this struct");
e.emit();
if let Some(f) = recovery_field {
fields.push(f);
}
// If the next token is a comma, then try to parse
// what comes next as additional fields, rather than
// bailing out until next `}`.
if self.token != token::Comma {
self.recover_stmt();
break;
self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
if self.token != token::Comma {
break;
}
}
}
}
@ -2676,9 +2696,10 @@ fn parse_struct_expr(&mut self, lo: Span, pth: ast::Path, mut attrs: ThinVec<Att
&[token::CloseDelim(token::Brace)]) {
Ok(()) => {}
Err(mut e) => {
e.span_label(struct_sp, "while parsing this struct");
e.emit();
self.recover_stmt();
break;
self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
self.eat(&token::Comma);
}
}
}
@ -4538,13 +4559,13 @@ fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockM
token::CloseDelim(token::DelimToken::Brace) => {
if brace_depth == 0 {
debug!("recover_stmt_ return - close delim {:?}", self.token);
return;
break;
}
brace_depth -= 1;
self.bump();
if in_block && bracket_depth == 0 && brace_depth == 0 {
debug!("recover_stmt_ return - block end {:?}", self.token);
return;
break;
}
}
token::CloseDelim(token::DelimToken::Bracket) => {
@ -4556,7 +4577,7 @@ fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockM
}
token::Eof => {
debug!("recover_stmt_ return - Eof");
return;
break;
}
token::Semi => {
self.bump();
@ -4564,7 +4585,17 @@ fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockM
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
return;
break;
}
}
token::Comma => {
if break_on_semi == SemiColonMode::Comma &&
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
break;
} else {
self.bump();
}
}
_ => {

13
src/test/ui/issues/issue-52496.rs Normal file
View File

@ -0,0 +1,13 @@
struct Foo { bar: f64, baz: i64, bat: i64 }
fn main() {
let _ = Foo { bar: .5, baz: 42 };
//~^ ERROR expected expression
//~| ERROR missing field `bat` in initializer of `Foo`
let bar = 1.5f32;
let _ = Foo { bar.into(), bat: -1, . };
//~^ ERROR expected one of
//~| ERROR mismatched types
//~| ERROR missing field `baz` in initializer of `Foo`
//~| ERROR expected identifier, found `.`
}

50
src/test/ui/issues/issue-52496.stderr Normal file
View File

@ -0,0 +1,50 @@
error: expected expression, found `.`
--> $DIR/issue-52496.rs:4:24
|
LL | let _ = Foo { bar: .5, baz: 42 };
| --- ^ expected expression
| |
| while parsing this struct
error: expected one of `,` or `}`, found `.`
--> $DIR/issue-52496.rs:8:22
|
LL | let _ = Foo { bar.into(), bat: -1, . };
| --- ^ expected one of `,` or `}` here
| |
| while parsing this struct
error: expected identifier, found `.`
--> $DIR/issue-52496.rs:8:40
|
LL | let _ = Foo { bar.into(), bat: -1, . };
| --- ^ expected identifier
| |
| while parsing this struct
error[E0063]: missing field `bat` in initializer of `Foo`
--> $DIR/issue-52496.rs:4:13
|
LL | let _ = Foo { bar: .5, baz: 42 };
| ^^^ missing `bat`
error[E0308]: mismatched types
--> $DIR/issue-52496.rs:8:19
|
LL | let _ = Foo { bar.into(), bat: -1, . };
| ^^^ expected f64, found f32
help: you can cast an `f32` to `f64` in a lossless way
|
LL | let _ = Foo { bar: bar.into().into(), bat: -1, . };
| ^^^^^^^^^^^^^^^
error[E0063]: missing field `baz` in initializer of `Foo`
--> $DIR/issue-52496.rs:8:13
|
LL | let _ = Foo { bar.into(), bat: -1, . };
| ^^^ missing `baz`
error: aborting due to 6 previous errors
Some errors occurred: E0063, E0308.
For more information about an error, try `rustc --explain E0063`.

4
src/test/ui/parser/removed-syntax-with-1.stderr
View File

@ -2,7 +2,9 @@ error: expected one of `,`, `.`, `?`, `}`, or an operator, found `with`
--> $DIR/removed-syntax-with-1.rs:8:25
|
LL | let b = S { foo: () with a };
| ^^^^ expected one of `,`, `.`, `?`, `}`, or an operator here
| - ^^^^ expected one of `,`, `.`, `?`, `}`, or an operator here
| |
| while parsing this struct
error[E0063]: missing field `bar` in initializer of `main::S`
--> $DIR/removed-syntax-with-1.rs:8:13

4
src/test/ui/parser/removed-syntax-with-2.stderr
View File

@ -2,7 +2,9 @@ error: expected one of `,` or `}`, found `a`
--> $DIR/removed-syntax-with-2.rs:8:31
|
LL | let b = S { foo: (), with a };
| ^ expected one of `,` or `}` here
| - ^ expected one of `,` or `}` here
| |
| while parsing this struct
error[E0425]: cannot find value `with` in this scope
--> $DIR/removed-syntax-with-2.rs:8:26

7
src/test/ui/parser/struct-field-numeric-shorthand.rs
View File

@ -1,6 +1,9 @@
struct Rgb(u8, u8, u8);
fn main() {
let _ = Rgb { 0, 1, 2 }; //~ ERROR expected identifier, found `0`
//~| ERROR missing fields `0`, `1`, `2` in initializer of `Rgb`
let _ = Rgb { 0, 1, 2 };
//~^ ERROR expected identifier, found `0`
//~| ERROR expected identifier, found `1`
//~| ERROR expected identifier, found `2`
//~| ERROR missing fields `0`, `1`, `2` in initializer of `Rgb`
}

22
src/test/ui/parser/struct-field-numeric-shorthand.stderr
View File

@ -1,17 +1,33 @@
error: expected identifier, found `0`
--> $DIR/struct-field-numeric-shorthand.rs:4:19
|
LL | let _ = Rgb { 0, 1, 2 }; //~ ERROR expected identifier, found `0`
LL | let _ = Rgb { 0, 1, 2 };
| --- ^ expected identifier
| |
| while parsing this struct
error: expected identifier, found `1`
--> $DIR/struct-field-numeric-shorthand.rs:4:22
|
LL | let _ = Rgb { 0, 1, 2 };
| --- ^ expected identifier
| |
| while parsing this struct
error: expected identifier, found `2`
--> $DIR/struct-field-numeric-shorthand.rs:4:25
|
LL | let _ = Rgb { 0, 1, 2 };
| --- ^ expected identifier
| |
| while parsing this struct
error[E0063]: missing fields `0`, `1`, `2` in initializer of `Rgb`
--> $DIR/struct-field-numeric-shorthand.rs:4:13
|
LL | let _ = Rgb { 0, 1, 2 }; //~ ERROR expected identifier, found `0`
LL | let _ = Rgb { 0, 1, 2 };
| ^^^ missing `0`, `1`, `2`
error: aborting due to 2 previous errors
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0063`.