From d4819b0279332bd831a690c449fd8593538ea024 Mon Sep 17 00:00:00 2001
From: cos <cos>
Date: Fri, 18 Feb 2022 17:27:29 +0100
Subject: fixup, wip: Process spans and their expansions

---
 autoload/ale/handlers/rust.vim | 67 +++++++++++++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 21 deletions(-)

diff --git a/autoload/ale/handlers/rust.vim b/autoload/ale/handlers/rust.vim
index 12a826e0..676e6c13 100644
--- a/autoload/ale/handlers/rust.vim
+++ b/autoload/ale/handlers/rust.vim
@@ -11,10 +11,41 @@ if !exists('g:ale_rust_ignore_secondary_spans')
     let g:ale_rust_ignore_secondary_spans = 0
 endif
 
+function! s:ProcessSpan(buffer, error, span) abort
+    if ale#Var(a:buffer, 'rust_ignore_secondary_spans') && !get(a:span, 'is_primary', 1)
+        return {}
+    endif
+
+    if !empty(a:span)
+        " :help ale-loclist-format
+        let l:output_line = {
+        \   'lnum': a:span.line_start,
+        \   'end_lnum': a:span.line_end,
+        \   'col': a:span.column_start,
+        \   'end_col': a:span.column_end-1,
+        \   'text': empty(a:span.label) ? a:error.message : printf('%s: %s', a:error.message, a:span.label),
+        \   'type': toupper(a:error.level[0]),
+        \}
+        " When operating on stdin rustc (and possibly others) gives '<anon>'
+        " as the file_name. Leaving the filename property of the loclist
+        " unpopulated makes ale connect such errors with the linted buffer.
+        if a:span.file_name !=# '<anon>'
+            let l:output_line['filename'] = a:span.file_name
+        endif
+
+        if has_key(a:error, 'rendered') && !empty(a:error.rendered)
+            let l:output_line.detail = a:error.rendered
+        endif
+
+        return l:output_line
+    endif
+    return {}
+endfunction
+
 function! ale#handlers#rust#HandleRustErrors(buffer, lines) abort
     let l:output = []
 
-    " Format of JSON
+    " Format of JSON is documented at
     " rustc: https://doc.rust-lang.org/rustc/json.html
     " cargo: https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages
     for l:diagnosticsline in a:lines
@@ -37,29 +68,23 @@ function! ale#handlers#rust#HandleRustErrors(buffer, lines) abort
             continue
         endif
 
-        for l:root_span in l:diagnostics.spans
-            let l:span = l:root_span
+        let l:spans = []
 
-            if ale#Var(a:buffer, 'rust_ignore_secondary_spans') && !get(l:span, 'is_primary', 1)
-                continue
-            endif
+        " FIXME One might also wish to loop over l:diagnostics.children and
+        "       their spans.
+        for l:span in l:diagnostics.spans
+            call add(l:spans, l:span)
 
-            if !empty(l:span)
-                " :help ale-loclist-format
-                let l:output_line = {
-                \   'filename': l:span.file_name,
-                \   'lnum': l:span.line_start,
-                \   'end_lnum': l:span.line_end,
-                \   'col': l:span.column_start,
-                \   'end_col': l:span.column_end-1,
-                \   'text': empty(l:span.label) ? l:diagnostics.message : printf('%s: %s', l:diagnostics.message, l:span.label),
-                \   'type': toupper(l:diagnostics.level[0]),
-                \}
-
-                if has_key(l:diagnostics, 'rendered') && !empty(l:diagnostics.rendered)
-                    let l:output_line.detail = l:diagnostics.rendered
-                endif
+            let l:expansion = l:span.expansion
+            if !empty(l:expansion)
+                let l:expansion_span = l:expansion.span
+                call add(l:spans, l:expansion_span)
+            endif
+        endfor
 
+        for l:span in l:spans
+            let l:output_line = s:ProcessSpan(a:buffer, l:diagnostics, l:span)
+            if !empty(l:output_line)
                 call add(l:output, l:output_line)
             endif
         endfor
-- 
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