panicked at 'assertion failed: !result.is_null()'

[jdm204]

Hi, getting a panic irrespective of the input file I try. Only tested so far on macOS with cargo --version 1.35.0 (6f3e9c367 2019-04-04).

`
-> file test.rs
test.rs: c program text, ASCII text

-> export RUST_BACKTRACE=1 && silicon test.rs -o test.png
thread 'main' panicked at 'assertion failed: !result.is_null()', /Users/jamie/.cargo/registry/src/github.com-1ecc6299db9ec823/core-graphics-0.17.3/src/context.rs:104:13
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
1: std::panicking::default_hook::{{closure}}
2: std::panicking::rust_panic_with_hook
3: std::panicking::begin_panic
4: font_kit::loaders::core_text::Font::rasterize_glyph
5: silicon::font::FontCollection::draw_text_mut
6: silicon::formatter::ImageFormatter::format
7: silicon::main
8: std::rt::lang_start::{{closure}}
9: main
`

[joequincy]

I have a nearly identical error (note that mine is missing line 6 from above)

~/>RUST_BACKTRACE=1 silicon --from-clipboard -l Ruby -o test.png
thread 'main' panicked at 'assertion failed: !result.is_null()', /Users/accountname/.cargo/registry/src/github.com-1ecc6299db9ec823/core-graphics-0.17.3/src/context.rs:104:13
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::panicking::default_hook::{{closure}}
   2: std::panicking::rust_panic_with_hook
   3: std::panicking::begin_panic
   4: font_kit::loaders::core_text::Font::rasterize_glyph
   5: silicon::font::FontCollection::draw_text_mut
   6: silicon::main
   7: std::rt::lang_start::{{closure}}
   8: main

Also tested using a filename instead of the --from-clipboard flag, and using Rust, Javascript, and PHP sources. All produce the same error and trace as above.

On OSX, using:
rust version 1.36.0 (a53f9df32 2019-07-03)
cargo 1.36.0 (c4fcfb725 2019-05-15)

[Aloxaf]

@NextTimeJim @joequincy Thank you for reporting it.

It seems like a bug of font-kit.

I don't have a macOS computer. Could you please test font-kit using cargo run --example render-glyph -- 'Monaco' A 32 to see whether it will print an 'A' on your terminal?

[joequincy]

I'm happy to explore this, but I'm not familiar with Rust development.
I navigated to where the font-kit crate is stored, at

/Users/accountname/.cargo/registry/src/github.com-1ecc6299db9ec823/font-kit-0.3.1

from there I ran cargo run --example render-glyph -- 'Monoid' A 32 and it rendered fine.

Running with 'Monaco', there are problems

If I ran cargo run --example render-glyph -- 'Monaco' A 32, the output was:

warning: type could implement `Copy`; consider adding `impl Copy`
  --> src/sources/core_text.rs:38:1
   |
38 | pub struct CoreTextSource;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: lint level defined here
  --> src/lib.rs:123:9
   |
123| #![warn(missing_copy_implementations)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Finished dev [unoptimized + debuginfo] target(s) in 44.11s
     Running `target/debug/examples/render-glyph Monaco A 32`
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Parse', src/libcore/result.rs:999:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

The Monaco font is installed on my system, so I'm not sure why this is the case.

Following on from this, I tried to specify the font when running silicon using the -f flag, but I received the same error backtrace as my prior comment.

[Aloxaf]

@joequincy Thank you
I tested it in the macOS virtual machine and finally found the reason.
It's caused by the whitespace (https://github.com/pcwalton/font-kit/issues/7)

[Aloxaf]

Fixed