Move reporting into its own crate

compiler/reporting/src/lib.rs

@@ -0,0 +1,14 @@
+#![warn(clippy::all, clippy::dbg_macro)]
+// I'm skeptical that clippy:large_enum_variant is a good lint to have globally enabled.
+//
+// It warns about a performance problem where the only quick remediation is
+// to allocate more on the heap, which has lots of tradeoffs - including making it
+// long-term unclear which allocations *need* to happen for compilation's sake
+// (e.g. recursive structures) versus those which were only added to appease clippy.
+//
+// Effectively optimizing data struture memory layout isn't a quick fix,
+// and encouraging shortcuts here creates bad incentives. I would rather temporarily
+// re-enable this when working on performance optimizations than have it block PRs.
+#![allow(clippy::large_enum_variant)]
+
+pub mod report;

compiler/reporting/src/report.rs

@@ -0,0 +1,115 @@
+use roc_module::symbol::{Interns, ModuleId, Symbol};
+use roc_problem::can::Problem;
+use roc_region::all::Region;
+use roc_types::pretty_print::content_to_string;
+use roc_types::subs::{Content, Subs};
+use std::path::PathBuf;
+
+/// A textual report.
+pub struct Report {
+    pub filename: PathBuf,
+    pub text: ReportText,
+}
+
+impl Report {
+    pub fn can_problem(_filename: PathBuf, _problem: Problem) -> Self {
+        // let text = match problem {
+        //     Problem::UnusedDef(symbol, region) => {
+        //         panic!("TODO implelment me!");
+        //     }
+        //     _ => {
+        //         panic!("TODO implement others");
+        //     }
+        // };
+
+        // Report { filename, text }
+        panic!("TODO implement me!");
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum ReportText {
+    /// A value. Render it qualified unless it was defined in the current module.
+    Value(Symbol),
+
+    /// A type. Render it using roc_types::pretty_print for now, but maybe
+    /// do something fancier later.
+    Type(Content),
+
+    /// Plain text
+    Plain(Box<str>),
+
+    /// Emphasized text (might be bold, italics, a different color, etc)
+    EmText(Box<str>),
+
+    /// A region in the original source
+    Region(Region),
+
+    /// A URL, which should be rendered as a hyperlink.
+    Url(Box<str>),
+
+    /// The documentation for this symbol.
+    Docs(Symbol),
+}
+
+impl ReportText {
+    /// Render to CI console output, where no colors are available.
+    pub fn render_ci(
+        self,
+        buf: &mut String,
+        subs: &mut Subs,
+        home: ModuleId,
+        src_lines: &[&str],
+        interns: &Interns,
+    ) {
+        use ReportText::*;
+
+        match self {
+            Plain(string) => buf.push_str(&string),
+            EmText(string) => {
+                // Since this is CI, the best we can do for emphasis are asterisks.
+                buf.push('*');
+                buf.push_str(&string);
+                buf.push('*');
+            }
+            Url(url) => {
+                buf.push('<');
+                buf.push_str(&url);
+                buf.push('>');
+            }
+            Value(symbol) => {
+                if symbol.module_id() == home {
+                    // Render it unqualified if it's in the current module.
+                    buf.push_str(symbol.ident_string(interns));
+                } else {
+                    buf.push_str(symbol.module_string(interns));
+                    buf.push('.');
+                    buf.push_str(symbol.ident_string(interns));
+                }
+            }
+            Type(content) => buf.push_str(content_to_string(content, subs, home, interns).as_str()),
+            Region(region) => {
+                panic!(
+                    "TODO convert these source lines and this region into a String: {:?}, {:?}",
+                    src_lines, region
+                );
+            }
+            Docs(_) => {
+                panic!("TODO implment docs");
+            }
+        }
+    }
+
+    /// Render to a color terminal using ANSI escape sequences
+    pub fn render_color_terminal(
+        &self,
+        _buf: &mut String,
+        _subs: &mut Subs,
+        _home: ModuleId,
+        _src_lines: &[&str],
+        _interns: &Interns,
+    ) {
+        // TODO do the same stuff as render_ci, but with colors via ANSI terminal escape codes!
+        // Examples of how to do this are in the source code of https://github.com/rtfeldman/console-print
+    }
+}