Use anyhow more idiomatically (#31052)

https://github.com/zed-industries/zed/issues/30972 brought up another
case where our context is not enough to track the actual source of the
issue: we get a general top-level error without inner error.

The reason for this was `.ok_or_else(|| anyhow!("failed to read HEAD
SHA"))?; ` on the top level.

The PR finally reworks the way we use anyhow to reduce such issues (or
at least make it simpler to bubble them up later in a fix).
On top of that, uses a few more anyhow methods for better readability.

* `.ok_or_else(|| anyhow!("..."))`, `map_err` and other similar error
conversion/option reporting cases are replaced with `context` and
`with_context` calls
* in addition to that, various `anyhow!("failed to do ...")` are
stripped with `.context("Doing ...")` messages instead to remove the
parasitic `failed to` text
* `anyhow::ensure!` is used instead of `if ... { return Err(...); }`
calls
* `anyhow::bail!` is used instead of `return Err(anyhow!(...));`

Release Notes:

- N/A

crates/gpui/src/platform/linux/headless/client.rs

@@ -95,9 +95,7 @@ impl LinuxClient for HeadlessClient {
         _handle: AnyWindowHandle,
         _params: WindowParams,
     ) -> anyhow::Result<Box<dyn PlatformWindow>> {
-        Err(anyhow::anyhow!(
-            "neither DISPLAY nor WAYLAND_DISPLAY is set. You can run in headless mode"
-        ))
+        anyhow::bail!("neither DISPLAY nor WAYLAND_DISPLAY is set. You can run in headless mode");
     }
 
     fn compositor_name(&self) -> &'static str {

crates/gpui/src/platform/linux/platform.rs

@@ -490,7 +490,7 @@ impl<P: LinuxClient + 'static> Platform for P {
                     let attributes = item.attributes().await?;
                     let username = attributes
                         .get("username")
-                        .ok_or_else(|| anyhow!("Cannot find username in stored credentials"))?;
+                        .context("Cannot find username in stored credentials")?;
                     let secret = item.secret().await?;
 
                     // we lose the zeroizing capabilities at this boundary,

crates/gpui/src/platform/linux/text_system.rs

@@ -3,7 +3,7 @@ use crate::{
     GlyphId, LineLayout, Pixels, PlatformTextSystem, Point, RenderGlyphParams, SUBPIXEL_VARIANTS,
     ShapedGlyph, ShapedRun, SharedString, Size, point, size,
 };
-use anyhow::{Context as _, Ok, Result, anyhow};
+use anyhow::{Context as _, Ok, Result};
 use collections::HashMap;
 use cosmic_text::{
     Attrs, AttrsList, CacheKey, Family, Font as CosmicTextFont, FontFeatures as CosmicFontFeatures,
@@ -232,7 +232,7 @@ impl CosmicTextSystemState {
             let font = self
                 .font_system
                 .get_font(font_id)
-                .ok_or_else(|| anyhow!("Could not load font"))?;
+                .context("Could not load font")?;
 
             // HACK: To let the storybook run and render Windows caption icons. We should actually do better font fallback.
             let allowed_bad_font_names = [
@@ -309,7 +309,7 @@ impl CosmicTextSystemState {
         glyph_bounds: Bounds<DevicePixels>,
     ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
         if glyph_bounds.size.width.0 == 0 || glyph_bounds.size.height.0 == 0 {
-            Err(anyhow!("glyph bounds are empty"))
+            anyhow::bail!("glyph bounds are empty");
         } else {
             let bitmap_size = glyph_bounds.size;
             let font = &self.loaded_fonts[params.font_id.0].font;
@@ -469,7 +469,7 @@ impl TryFrom<&FontFeatures> for CosmicFontFeatures {
                 .0
                 .as_bytes()
                 .try_into()
-                .map_err(|_| anyhow!("Incorrect feature flag format"))?;
+                .context("Incorrect feature flag format")?;
 
             let tag = cosmic_text::FeatureTag::new(&name_bytes);
 

crates/gpui/src/platform/linux/wayland/display.rs

@@ -3,6 +3,7 @@ use std::{
     hash::{Hash, Hasher},
 };
 
+use anyhow::Context as _;
 use uuid::Uuid;
 use wayland_backend::client::ObjectId;
 
@@ -28,11 +29,11 @@ impl PlatformDisplay for WaylandDisplay {
     }
 
     fn uuid(&self) -> anyhow::Result<Uuid> {
-        if let Some(name) = &self.name {
-            Ok(Uuid::new_v5(&Uuid::NAMESPACE_DNS, name.as_bytes()))
-        } else {
-            Err(anyhow::anyhow!("Wayland display does not have a name"))
-        }
+        let name = self
+            .name
+            .as_ref()
+            .context("Wayland display does not have a name")?;
+        Ok(Uuid::new_v5(&Uuid::NAMESPACE_DNS, name.as_bytes()))
     }
 
     fn bounds(&self) -> Bounds<Pixels> {

crates/gpui/src/platform/linux/x11/display.rs

@@ -1,4 +1,4 @@
-use anyhow::Result;
+use anyhow::Context as _;
 use uuid::Uuid;
 use x11rb::{connection::Connection as _, xcb_ffi::XCBConnection};
 
@@ -17,12 +17,11 @@ impl X11Display {
         scale_factor: f32,
         x_screen_index: usize,
     ) -> anyhow::Result<Self> {
-        let Some(screen) = xcb.setup().roots.get(x_screen_index) else {
-            return Err(anyhow::anyhow!(
-                "No screen found with index {}",
-                x_screen_index
-            ));
-        };
+        let screen = xcb
+            .setup()
+            .roots
+            .get(x_screen_index)
+            .with_context(|| format!("No screen found with index {x_screen_index}"))?;
         Ok(Self {
             x_screen_index,
             bounds: Bounds {
@@ -42,7 +41,7 @@ impl PlatformDisplay for X11Display {
         DisplayId(self.x_screen_index as u32)
     }
 
-    fn uuid(&self) -> Result<Uuid> {
+    fn uuid(&self) -> anyhow::Result<Uuid> {
         Ok(self.uuid)
     }