Implement text wrapping for most diagnostic messages (#446)

This PR adds basic text wrapping to diagnostic messages (except those
attached to snippets) to avoid needing to wrap notes/helps by hand when
writing diagnostics.

Author: mcy

experimental/parser/testdata/lexer/strings/unclosed2.proto.stderr.txt

@@ -3,6 +3,7 @@ error: unterminated string literal
    |
  1 | '\'
    | ^^^ expected to be terminated by `'`
-   = note: this string appears to end in an escaped quote; replace `\'` with `\\''`
+   = note: this string appears to end in an escaped quote; replace `\'` with
+           `\\''`
 
 encountered 1 error

experimental/report/diff.go

@@ -87,24 +87,24 @@ func unifiedDiff(span Span, edits []Edit) (Span, []hunk) {
 
 	// Partition offsets into overlapping lines. That is, this connects together
 	// all edit spans whose end and start are not separated by a newline.
-	prev := &edits[0]
-	parts := slicesx.Partition(edits, func(_, next *Edit) bool {
-		if next == prev {
+	prev := 0
+	parts := slicesx.SplitFunc(edits, func(i int, next Edit) bool {
+		if i == prev {
 			return false
 		}
 
-		chunk := src[prev.End:next.Start]
+		chunk := src[edits[i-1].End:next.Start]
 		if !strings.Contains(chunk, "\n") {
 			return false
 		}
 
-		prev = next
+		prev = i
 		return true
 	})
 
 	var out []hunk
 	var prevHunk int
-	parts(func(_ int, edits []Edit) bool {
+	parts(func(edits []Edit) bool {
 		// First, figure out the start and end of the modified region.
 		start, end := edits[0].Start, edits[0].End
 		for _, edit := range edits[1:] {

experimental/report/renderer.go

@@ -18,12 +18,14 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"math"
 	"math/bits"
 	"slices"
 	"strconv"
 	"strings"
 	"unicode"
 
+	"github.com/bufbuild/protocompile/internal/ext/iterx"
 	"github.com/bufbuild/protocompile/internal/ext/slicesx"
 	"github.com/bufbuild/protocompile/internal/ext/stringsx"
 )
@@ -186,7 +188,8 @@ func (r *renderer) diagnostic(report *Report, d Diagnostic) {
 	// For the other styles, we imitate the Rust compiler. See
 	// https://github.com/rust-lang/rustc-dev-guide/blob/master/src/diagnostics.md
 
-	fmt.Fprint(r, r.ss.BoldForLevel(d.level), level, ": ", d.message, r.ss.reset)
+	fmt.Fprint(r, r.ss.BoldForLevel(d.level), level, ": ")
+	r.WriteWrapped(d.message, MaxMessageWidth)
 
 	locations := make([][2]Location, len(d.snippets))
 	for i, snip := range d.snippets {
@@ -210,13 +213,14 @@ func (r *renderer) diagnostic(report *Report, d Diagnostic) {
 	r.margin = max(2, len(strconv.Itoa(greatestLine))) // Easier than messing with math.Log10()
 
 	// Render all the diagnostic windows.
-	parts := slicesx.Partition(d.snippets, func(a, b *snippet) bool {
-		if len(a.edits) > 0 || len(b.edits) > 0 {
+	parts := slicesx.PartitionKey(d.snippets, func(snip snippet) any {
+		if len(snip.edits) > 0 {
 			// Suggestions are always rendered in their own windows.
-			return true
+			// Return a fresh pointer, since that will always compare as
+			// distinct.
+			return new(int)
 		}
-
-		return a.Path() != b.Path()
+		return snip.Path()
 	})
 
 	parts(func(i int, snippets []snippet) bool {
@@ -261,34 +265,33 @@ func (r *renderer) diagnostic(report *Report, d Diagnostic) {
 		fmt.Fprintf(r, "--> %s", d.inFile)
 	}
 
-	// Render the footers. For simplicity we collect them into an array first.
-	footers := make([][3]string, 0, len(d.notes)+len(d.help)+len(d.debug))
-	for _, note := range d.notes {
-		footers = append(footers, [3]string{r.ss.bRemark, "note", note})
-	}
-	for _, help := range d.help {
-		footers = append(footers, [3]string{r.ss.bRemark, "help", help})
+	type footer struct {
+		color, label, text string
 	}
-	if r.ShowDebug {
-		for _, debug := range d.debug {
-			footers = append(footers, [3]string{r.ss.bError, "debug", debug})
+	footers := iterx.Chain(
+		slicesx.Map(d.notes, func(s string) footer { return footer{r.ss.bRemark, "note", s} }),
+		slicesx.Map(d.help, func(s string) footer { return footer{r.ss.bRemark, "help", s} }),
+		slicesx.Map(d.debug, func(s string) footer { return footer{r.ss.bError, "debug", s} }),
+	)
+
+	footers(func(f footer) bool {
+		isDebug := f.label == "debug"
+		if isDebug && !r.ShowDebug {
+			return true
 		}
-	}
-	for _, footer := range footers {
+
 		r.WriteString("\n")
-		r.WriteString(r.ss.nAccent)
 		r.WriteSpaces(r.margin)
-		r.WriteString(" = ")
-		fmt.Fprint(r, footer[0], footer[1], ": ", r.ss.reset)
-		for i, line := range strings.Split(footer[2], "\n") {
-			if i > 0 {
-				r.WriteString("\n")
-				margin := r.margin + 3 + len(footer[1]) + 2
-				r.WriteSpaces(margin)
-			}
-			r.WriteString(line)
+		fmt.Fprintf(r, "%s = %s%s: %s", r.ss.nAccent, f.color, f.label, r.ss.reset)
+
+		if isDebug {
+			r.WriteWrapped(f.text, math.MaxInt)
+		} else {
+			r.WriteWrapped(f.text, MaxMessageWidth)
 		}
-	}
+
+		return true
+	})
 
 	r.WriteString(r.ss.reset)
 	r.WriteString("\n\n")
@@ -482,7 +485,7 @@ func (r *renderer) window(w *window) {
 
 	// Next, we can render the underline parts. This aggregates all underlines
 	// for the same line into rendered chunks
-	parts := slicesx.Partition(w.underlines, func(a, b *underline) bool { return a.line != b.line })
+	parts := slicesx.PartitionKey(w.underlines, func(u underline) int { return u.line })
 	parts(func(_ int, part []underline) bool {
 		cur := &info[part[0].line-w.start]
 		cur.shouldEmit = true
@@ -517,8 +520,7 @@ func (r *renderer) window(w *window) {
 
 		// Now, convert the buffer into a proper string.
 		var out strings.Builder
-		parts := slicesx.Partition(buf, func(a, b *byte) bool { return *a != *b })
-		parts(func(_ int, line []byte) bool {
+		slicesx.Partition(buf)(func(_ int, line []byte) bool {
 			level := Level(line[0])
 			if line[0] == 0 {
 				out.WriteString(r.ss.reset)
@@ -906,7 +908,7 @@ func (r *renderer) suggestion(snip snippet) {
 	r.WriteString(r.ss.nAccent)
 	r.WriteSpaces(r.margin)
 	r.WriteString("help: ")
-	r.WriteString(snip.message)
+	r.WriteWrapped(snip.message, MaxMessageWidth)
 
 	// Add a blank line after the file. This gives the diagnostic window some
 	// visual breathing room.

experimental/report/span.go

@@ -27,9 +27,6 @@ import (
 	"github.com/bufbuild/protocompile/internal/iter"
 )
 
-// TabstopWidth is the size we render all tabstops as.
-const TabstopWidth int = 4
-
 // Spanner is any type with a [Span].
 type Spanner interface {
 	// Should return the zero [Span] to indicate that it does not contribute

experimental/report/testdata/i18n.yaml.color.txt

@@ -1,4 +1,4 @@
-⟨b.red⟩error: emoji, CJK, bidi⟨reset⟩
+⟨b.red⟩error: emoji, CJK, bidi
 ⟨blu⟩  --> foo.proto:5:9
    |
 ⟨blu⟩ 5 | ⟨reset⟩message 🐈<U+200D>⬛ {
@@ -10,7 +10,7 @@
 ⟨blu⟩ 1 | ⟨reset⟩import "חתול שחור.proto";
 ⟨blu⟩   | ⟨reset⟩        ⟨b.blu⟩---------------⟨reset⟩ ⟨b.blu⟩bidi works if it's quoted, at least⟨reset⟩
 
-⟨b.red⟩error: bidi (Arabic, Hebrew, Farsi, etc) is broken in some contexts⟨reset⟩
+⟨b.red⟩error: bidi (Arabic, Hebrew, Farsi, etc) is broken in some contexts
 ⟨blu⟩  --> foo.proto:7:10
    |
 ⟨blu⟩ 7 | ⟨reset⟩  string القطة السوداء = 2;

experimental/report/testdata/multi-file.yaml.color.txt

@@ -1,4 +1,4 @@
-⟨b.red⟩error: two files⟨reset⟩
+⟨b.red⟩error: two files
 ⟨blu⟩  --> foo.proto:3:9
    |
 ⟨blu⟩ 3 | ⟨reset⟩package abc.xyz;
@@ -11,7 +11,7 @@
 ⟨blu⟩ 3 | ⟨reset⟩package abc.xyz2;
 ⟨blu⟩   | ⟨reset⟩        ⟨b.blu⟩-------⟨reset⟩ ⟨b.blu⟩baz⟨reset⟩
 
-⟨b.red⟩error: three files⟨reset⟩
+⟨b.red⟩error: three files
 ⟨blu⟩  --> foo.proto:3:9
    |
 ⟨blu⟩ 3 | ⟨reset⟩package abc.xyz;

experimental/report/testdata/multi-underline.yaml.color.txt

@@ -1,4 +1,4 @@
-⟨b.red⟩error: `size_t` is not a built-in Protobuf type⟨reset⟩
+⟨b.red⟩error: `size_t` is not a built-in Protobuf type
 ⟨blu⟩  --> foo.proto:6:12
    |
 ⟨blu⟩ 1 | ⟨reset⟩syntax = "proto4"
@@ -8,7 +8,7 @@
 ⟨blu⟩ 6 | ⟨reset⟩  required size_t x = 0;
 ⟨blu⟩   | ⟨reset⟩           ⟨b.red⟩^^^^^⟨reset⟩ ⟨b.red⟩⟨reset⟩
 
-⟨b.ylw⟩warning: these are pretty bad names⟨reset⟩
+⟨b.ylw⟩warning: these are pretty bad names
 ⟨blu⟩  --> foo.proto:3:9
    |
 ⟨blu⟩ 3 | ⟨reset⟩package abc.xyz;

experimental/report/testdata/multiline.yaml.color.txt

@@ -1,12 +1,12 @@
-⟨b.ylw⟩warning: whole block⟨reset⟩
+⟨b.ylw⟩warning: whole block
 ⟨blu⟩  --> foo.proto:5:1
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩/ ⟨reset⟩message Blah {
 ⟨blu⟩...  ⟨b.ylw⟩|
 ⟨blu⟩12 | ⟨b.ylw⟩| ⟨reset⟩}
 ⟨blu⟩   | ⟨b.ylw⟩\_^ this block⟨reset⟩
 
-⟨b.ylw⟩warning: nested blocks⟨reset⟩
+⟨b.ylw⟩warning: nested blocks
 ⟨blu⟩  --> foo.proto:5:1
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩/ ⟨reset⟩message Blah {
@@ -18,7 +18,7 @@
 ⟨blu⟩12 | ⟨b.ylw⟩| ⟨reset⟩}
 ⟨blu⟩   | ⟨b.ylw⟩\___^ this block⟨reset⟩
 
-⟨b.ylw⟩warning: parallel blocks⟨reset⟩
+⟨b.ylw⟩warning: parallel blocks
 ⟨blu⟩  --> foo.proto:5:1
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩/ ⟨reset⟩message Blah {
@@ -31,7 +31,7 @@
 ⟨blu⟩12 | ⟨b.blu⟩/ ⟨reset⟩}
 ⟨blu⟩   | ⟨b.blu⟩\_- and this block⟨reset⟩
 
-⟨b.ylw⟩warning: nested blocks same start⟨reset⟩
+⟨b.ylw⟩warning: nested blocks same start
 ⟨blu⟩  --> foo.proto:5:1
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩/ ⟨b.blu⟩/ ⟨reset⟩message Blah {
@@ -41,7 +41,7 @@
 ⟨blu⟩12 | ⟨b.ylw⟩| ⟨reset⟩}
 ⟨blu⟩   | ⟨b.ylw⟩\___^ this block⟨reset⟩
 
-⟨b.ylw⟩warning: nested blocks same end⟨reset⟩
+⟨b.ylw⟩warning: nested blocks same end
 ⟨blu⟩  --> foo.proto:5:1
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩/ ⟨reset⟩message Blah {
@@ -52,7 +52,7 @@
 ⟨blu⟩   | ⟨b.ylw⟩\___^ this block
 ⟨blu⟩   | ⟨b.ylw⟩  ⟨b.blu⟩\_- and this block⟨reset⟩
 
-⟨b.ylw⟩warning: nested overlap⟨reset⟩
+⟨b.ylw⟩warning: nested overlap
 ⟨blu⟩  --> foo.proto:5:1
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩/ ⟨reset⟩message Blah {
@@ -64,7 +64,7 @@
 ⟨blu⟩12 |   ⟨b.blu⟩| ⟨reset⟩}
 ⟨blu⟩   |   ⟨b.blu⟩\_- and this block⟨reset⟩
 
-⟨b.ylw⟩warning: nesting just the braces⟨reset⟩
+⟨b.ylw⟩warning: nesting just the braces
 ⟨blu⟩  --> foo.proto:5:15
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩  ⟨reset⟩message Blah {
@@ -78,7 +78,7 @@
 ⟨blu⟩12 | ⟨b.ylw⟩| ⟨reset⟩}
 ⟨blu⟩   | ⟨b.ylw⟩\___^ this block⟨reset⟩
 
-⟨b.ylw⟩warning: nesting just the braces same start⟨reset⟩
+⟨b.ylw⟩warning: nesting just the braces same start
 ⟨blu⟩  --> foo.proto:5:15
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩  ⟨b.blu⟩  ⟨reset⟩message Blah {
@@ -90,7 +90,7 @@
 ⟨blu⟩12 | ⟨b.ylw⟩| ⟨reset⟩}
 ⟨blu⟩   | ⟨b.ylw⟩\___^ this block⟨reset⟩
 
-⟨b.ylw⟩warning: nesting just the braces same start (2)⟨reset⟩
+⟨b.ylw⟩warning: nesting just the braces same start (2)
 ⟨blu⟩  --> foo.proto:5:15
    |
 ⟨blu⟩ 5 | ⟨b.blu⟩  ⟨b.ylw⟩  ⟨reset⟩message Blah {
@@ -102,7 +102,7 @@
 ⟨blu⟩12 | ⟨b.blu⟩| ⟨reset⟩}
 ⟨blu⟩   | ⟨b.blu⟩\___- this block⟨reset⟩
 
-⟨b.ylw⟩warning: braces nesting overlap⟨reset⟩
+⟨b.ylw⟩warning: braces nesting overlap
 ⟨blu⟩  --> foo.proto:5:15
    |
 ⟨blu⟩ 5 | ⟨b.ylw⟩  ⟨reset⟩message Blah {
@@ -116,7 +116,7 @@
 ⟨blu⟩12 |   ⟨b.blu⟩| ⟨reset⟩}
 ⟨blu⟩   |   ⟨b.blu⟩\_- and this block⟨reset⟩
 
-⟨b.ylw⟩warning: braces nesting overlap (2)⟨reset⟩
+⟨b.ylw⟩warning: braces nesting overlap (2)
 ⟨blu⟩  --> foo.proto:7:17
    |
 ⟨blu⟩ 5 | ⟨b.blu⟩  ⟨reset⟩message Blah {

experimental/report/testdata/no-snippets.yaml

@@ -18,6 +18,9 @@ diagnostics:
   - message: "system not supported"
     level: LEVEL_ERROR
 
+  - message: "this diagnostic message is comically long to illustrate message wrapping; real diagnostics should probably avoid doing this"
+    level: LEVEL_ERROR
+
   - message: 'could not open file "foo.proto": os error 2: no such file or directory'
     level: LEVEL_ERROR
     in_file: foo.proto
@@ -28,3 +31,15 @@ diagnostics:
     notes: ["that means that the file is screaming"]
     help: ["you should delete it to put it out of its misery"]
     debug: ["0xaaaaaaaaaaaaaaaa"]
+
+  - message: "very long footers"
+    level: LEVEL_REMARK
+    in_file: foo.proto
+    notes: 
+      - "this footer is very very very very very very very very very very very very very very very very very very long"
+      - "this one is also long, and it's also supercalifragilistcexpialidocious, leading to a very early break"
+    help:
+      - "this help is very long (and triggers the same word-wrapping code path)"
+      - "this one contains a newline\nwhich overrides the default word wrap behavior (but this line is wrapped naturally)"
+    debug:
+      - "debug lines are never wrapped, no matter how crazy long they are, since they can contain stack traces"

experimental/report/testdata/no-snippets.yaml.color.txt

@@ -1,13 +1,29 @@
-⟨b.red⟩error: system not supported⟨reset⟩⟨reset⟩
+⟨b.red⟩error: system not supported⟨reset⟩
 
-⟨b.red⟩error: could not open file "foo.proto": os error 2: no such file or directory⟨reset⟩
+⟨b.red⟩error: this diagnostic message is comically long to illustrate message wrapping;
+       real diagnostics should probably avoid doing this⟨reset⟩
+
+⟨b.red⟩error: could not open file "foo.proto": os error 2: no such file or directory
 ⟨blu⟩ --> foo.proto⟨reset⟩
 
-⟨b.ylw⟩warning: file consists only of the byte `0xaa`⟨reset⟩
+⟨b.ylw⟩warning: file consists only of the byte `0xaa`
+⟨blu⟩ --> foo.proto
+  ⟨blu⟩ = ⟨b.cyn⟩note: ⟨reset⟩that means that the file is screaming
+  ⟨blu⟩ = ⟨b.cyn⟩help: ⟨reset⟩you should delete it to put it out of its misery
+  ⟨blu⟩ = ⟨b.red⟩debug: ⟨reset⟩0xaaaaaaaaaaaaaaaa⟨reset⟩
+
+⟨b.cyn⟩remark: very long footers
 ⟨blu⟩ --> foo.proto
-⟨blu⟩   = ⟨b.cyn⟩note: ⟨reset⟩that means that the file is screaming
-⟨blu⟩   = ⟨b.cyn⟩help: ⟨reset⟩you should delete it to put it out of its misery
-⟨blu⟩   = ⟨b.red⟩debug: ⟨reset⟩0xaaaaaaaaaaaaaaaa⟨reset⟩
+  ⟨blu⟩ = ⟨b.cyn⟩note: ⟨reset⟩this footer is very very very very very very very very very very very
+           very very very very very very very long
+  ⟨blu⟩ = ⟨b.cyn⟩note: ⟨reset⟩this one is also long, and it's also
+           supercalifragilistcexpialidocious, leading to a very early break
+  ⟨blu⟩ = ⟨b.cyn⟩help: ⟨reset⟩this help is very long (and triggers the same word-wrapping code
+           path)
+  ⟨blu⟩ = ⟨b.cyn⟩help: ⟨reset⟩this one contains a newline
+           which overrides the default word wrap behavior (but this line is
+           wrapped naturally)
+  ⟨blu⟩ = ⟨b.red⟩debug: ⟨reset⟩debug lines are never wrapped, no matter how crazy long they are, since they can contain stack traces⟨reset⟩
 
-⟨b.red⟩encountered 2 errors and 1 warning
+⟨b.red⟩encountered 3 errors and 1 warning
 ⟨reset⟩