Point spans to inner elements of format strings #52649

estebank · 2018-07-23T15:39:41Z

Point at missing positional specifiers in string literal

error: invalid reference to positional arguments 3, 4 and 5 (there are 3 arguments)
  --> $DIR/ifmt-bad-arg.rs:34:38
   |
LL |     format!("{name} {value} {} {} {} {} {} {}", 0, name=1, value=2);
   |                                      ^^ ^^ ^^
   |
   = note: positional arguments are zero-based

Point at named formatting specifier in string literal

error: there is no argument named `foo`
  --> $DIR/ifmt-bad-arg.rs:37:17
   |
LL |     format!("{} {foo} {} {bar} {}", 1, 2, 3);
   |                 ^^^^^

Update label for formatting string in "multiple unused formatting arguments" to be more correct

error: multiple unused formatting arguments
  --> $DIR/ifmt-bad-arg.rs:42:17
   |
LL |     format!("", 1, 2);               //~ ERROR: multiple unused formatting arguments
   |             --  ^  ^
   |             |
   |             multiple missing formatting specifiers

When using printf string formatting, provide a structured suggestion instead of a note

error: multiple unused formatting arguments
  --> $DIR/format-foreign.rs:12:30
   |
LL |     println!("%.*3$s %s!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
   |              --------------  ^^^^^^^^  ^^^^^^^  ^
   |              |
   |              multiple missing formatting specifiers
   |
   = note: printf formatting not supported; see the documentation for `std::fmt`
help: format specifiers in Rust are written using `{}`
   |
LL |     println!("{:.2$} {}!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
   |               ^^^^^^ ^^

rust-highfive · 2018-07-23T15:39:52Z

r? @alexcrichton

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estebank · 2018-07-23T15:40:13Z

src/test/ui/macros/macro-backtrace-println.stderr

 |
 LL | ($fmt:expr) => (myprint!(concat!($fmt, "/n"))); //~ ERROR no arguments were given
- | ^^^^^^^^^^^^^^^^^^^
+ |  ^^


Do not apply if not a string literal.

estebank · 2018-07-23T15:40:53Z

src/test/ui/ifmt-bad-arg.stderr

+ --> $DIR/ifmt-bad-arg.rs:34:14
+ |
+LL | format!("{name} {value} {} {} {} {} {} {}", 0, name=1, value=2);
+ | ^^^^^^ ^^^^^^^ ^^ ^^ ^^ ^^ ^^ ^^


Point only to positional arguments 3, 4 and 5.

estebank · 2018-07-23T15:41:07Z

src/test/ui/ifmt-bad-arg.stderr

+ --> $DIR/ifmt-bad-arg.rs:29:14
+ |
+LL | format!("{0} {1} {2}", 1, 2);
+ | ^^^ ^^^ ^^^


Point only to positional argument 2.

alexcrichton · 2018-07-23T21:44:35Z

This looks like a fantastic idea to me! I'll take a closer look with tests passing?

…terals

estebank · 2018-07-23T23:04:35Z

I'm really happy with how it ended up looking.

@alexcrichton do you think I should add a secondary span pointing at the complete string for all of these errors? Also, I feel we should also add labels to the primary spans, but I can do these things in a separate PR.

estebank · 2018-07-24T01:23:22Z

cc @nikomatsakis and @oli-obk who might have ideas around what these should look like.

oli-obk

Absolutely great. This deserves its own blog/reddit/users post. It's gonna blow ppls minds

oli-obk · 2018-07-24T07:55:56Z

src/libfmt_macros/lib.rs

@@ -154,6 +154,7 @@ pub struct Parser<'a> {
 style: Option<usize>,
 /// How many newlines have been seen in the string so far, to adjust the error spans
 seen_newlines: usize,
+ pub arg_places: Vec<(usize, usize)>,


so these are offsets into the format string? A comment would be nice (I'm using this struct in clippy ^^)

Added docs.

oli-obk · 2018-07-24T07:57:57Z

src/test/ui/ifmt-bad-arg.stderr

+ --> $DIR/ifmt-bad-arg.rs:34:38
+ |
+LL | format!("{name} {value} {} {} {} {} {} {}", 0, name=1, value=2);
+ | ^^ ^^ ^^


this is absolutely great

oli-obk · 2018-07-24T07:58:47Z

src/test/ui/ifmt-bad-arg.stderr

+LL | format!("", 1, 2); //~ ERROR: multiple unused formatting arguments
+ | -- ^ ^
+ | |
+ | multiple missing formatting arguments


it's not missing formatting arguments, it's missing formatting specifiers, right?

oli-obk · 2018-07-24T08:00:16Z

src/test/ui/ifmt-bad-arg.stderr

+LL | format!("{"); //~ ERROR: expected `'}'` but string was terminated
+ | ^ expected `'}'` in format string
+ |
+ = note: if you intended to print `{`, you can escape it using `{{`


Can you make this a structured suggestion?

I'll look into this as a follow up, because the output would look a bit bad (it'd have to suggest {" as it is now, which is hard to understand).

oli-obk · 2018-07-24T08:01:00Z

src/test/ui/ifmt-bad-arg.stderr

+LL | format!("foo %s baz", "bar"); //~ ERROR: argument never used
+ | ^^^^^
+ |
+ = help: `%s` should be written as `{}`


this has no span associated with it

oli-obk · 2018-07-25T07:16:07Z

@bors r+ wonderful

bors · 2018-07-25T07:16:08Z

📌 Commit 9a893cc has been approved by oli-obk

Point spans to inner elements of format strings - Point at missing positional specifiers in string literal ``` error: invalid reference to positional arguments 3, 4 and 5 (there are 3 arguments) --> $DIR/ifmt-bad-arg.rs:34:38 | LL | format!("{name} {value} {} {} {} {} {} {}", 0, name=1, value=2); | ^^ ^^ ^^ | = note: positional arguments are zero-based ``` - Point at named formatting specifier in string literal ``` error: there is no argument named `foo` --> $DIR/ifmt-bad-arg.rs:37:17 | LL | format!("{} {foo} {} {bar} {}", 1, 2, 3); | ^^^^^ ``` - Update label for formatting string in "multiple unused formatting arguments" to be more correct ``` error: multiple unused formatting arguments --> $DIR/ifmt-bad-arg.rs:42:17 | LL | format!("", 1, 2); //~ ERROR: multiple unused formatting arguments | -- ^ ^ | | | multiple missing formatting specifiers ``` - When using `printf` string formatting, provide a structured suggestion instead of a note ``` error: multiple unused formatting arguments --> $DIR/format-foreign.rs:12:30 | LL | println!("%.*3$s %s!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments | -------------- ^^^^^^^^ ^^^^^^^ ^ | | | multiple missing formatting specifiers | = note: printf formatting not supported; see the documentation for `std::fmt` help: format specifiers in Rust are written using `{}` | LL | println!("{:.2$} {}!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments | ^^^^^^ ^^ ```

@ghost

Rollup of 16 pull requests Successful merges: - #52558 (Add tests for ICEs which no longer repro) - #52610 (Clarify what a task is) - #52617 (Don't match on region kinds when reporting NLL errors) - #52635 (Fix #[linkage] propagation though generic functions) - #52647 (Suggest to take and ignore args while closure args count mismatching) - #52649 (Point spans to inner elements of format strings) - #52654 (Format linker args in a way that works for gcc and ld) - #52667 (update the stdsimd submodule) - #52674 (Impl Executor for Box<E: Executor>) - #52690 (ARM: expose `rclass` and `dsp` target features) - #52692 (Improve readability in a few sorts) - #52695 (Hide some lints which are not quite right the way they are reported to the user) - #52718 (State default capacity for BufReader/BufWriter) - #52721 (std::ops::Try impl for std::task::Poll) - #52723 (rustc: Register crates under their real names) - #52734 (sparc ABI issue - structure returning from function is returned in 64bit registers (with tests)) Failed merges: - #52678 ([NLL] Use better spans in some errors) r? @ghost

Use suggestions for shell format arguments Follow up to rust-lang#52649.

Esteban Küber added 2 commits July 22, 2018 23:09

Point at internal span in format string

38abca8

Point at incorrect named arg in format string

4230659

rust-highfive assigned alexcrichton Jul 23, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 23, 2018

estebank commented Jul 23, 2018

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estebank added 2 commits July 23, 2018 15:09

Point only at invalid positional arguments

6bcf877

Only point at inside of string literals if they're actually string li…

c55a698

…terals

estebank changed the title ~~[WIP] Point spans to inner elements of format strings~~ Point spans to inner elements of format strings Jul 23, 2018

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Add test for raw string

bde2be0

estebank force-pushed the fmt-span branch from 665096a to bde2be0 Compare July 23, 2018 23:03

oli-obk reviewed Jul 24, 2018

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estebank added 3 commits July 24, 2018 09:46

Add documentation for Parser::arg_places

f487e39

Reword missing formatting arguments label

f9e3762

Use suggestions for printf format

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estebank added 3 commits July 24, 2018 18:44

Fix unittest

3298b9f

Rename method and remove commented out code

7bd94e0

Add span label for format str missing specifier

9a893cc

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 25, 2018

Mark-Simulacrum mentioned this pull request Jul 26, 2018

Rollup of 16 pull requests #52735

Merged

bors merged commit 9a893cc into rust-lang:master Jul 26, 2018

This was referenced Jul 31, 2018

Use suggestions for shell format arguments #52888

Merged

Suggest comma when writing println!("{}" a); #52397

Merged

pietroalbini added a commit to pietroalbini/rust that referenced this pull request Aug 1, 2018

Rollup merge of rust-lang#52888 - estebank:shell-sugg, r=oli-obk

a8ed603

Use suggestions for shell format arguments Follow up to rust-lang#52649.

This was referenced Aug 30, 2018

Incorrect span for multiline format string with errors #53836

Closed

Subpar span on multiline format string with unclosed brace #53837

Closed

estebank mentioned this pull request May 28, 2020

Inline asm errors don't report file/line no information #72664

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Point spans to inner elements of format strings #52649

Point spans to inner elements of format strings #52649

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Point spans to inner elements of format strings #52649

Point spans to inner elements of format strings #52649

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