Add support for range diagnostics under cursor

autoload/lsp/internal/diagnostics/under_cursor.vim

@@ -29,20 +29,29 @@ function! lsp#internal#diagnostics#under_cursor#get_diagnostic(...) abort
     let l:line = line('.')
     let l:col = col('.')
 
+    return lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, l:line, l:col)
+endfunction
+
+" Returns a diagnostic object, or empty dictionary if no diagnostics are
+" available.
+function! lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(diagnostics, line, col) abort
     let l:closest_diagnostic = {}
     let l:closest_distance = -1
+    let l:closest_end_col = -1
 
-    for l:diagnostic in l:diagnostics
+    for l:diagnostic in a:diagnostics
         let [l:start_line, l:start_col] = lsp#utils#position#lsp_to_vim('%', l:diagnostic['range']['start'])
+        let [l:end_line, l:end_col] = lsp#utils#position#lsp_to_vim('%', l:diagnostic['range']['end'])
 
-        if l:line == l:start_line
-            let l:distance = abs(l:start_col - l:col)
+        if (a:line > l:start_line || (a:line == l:start_line && a:col >= l:start_col)) &&
+              \ (a:line < l:end_line || (a:line == l:end_line && a:col < l:end_col))
+            let l:distance = abs(l:start_col - a:col)
             if l:closest_distance < 0 || l:distance < l:closest_distance
+                let l:closest_end_col = l:end_col
                 let l:closest_diagnostic = l:diagnostic
                 let l:closest_distance = l:distance
             endif
         endif
     endfor
-
     return l:closest_diagnostic
 endfunction

test/lsp/internal/diagnostics/under_cursor.vimspec

@@ -0,0 +1,88 @@
+Describe lsp#internal#diagnostics#under_cursor
+    " refer to lsp#test#projectdir('go') . '/documentdiagnostics.go'
+
+    It should not trigger diagnostics when cursor is outside diagnostic range
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 1, 1), {})
+    End
+
+    It should trigger diagnostic when cursor is exactly at start position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        let l:expected = { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 7, 13), l:expected)
+    End
+
+    It should not trigger diagnostic when cursor is at line before start position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 6, 13), {})
+    End
+
+    It should not trigger diagnostic when cursor is one character before start position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 7, 12), {})
+    End
+
+    It should trigger diagnostic when cursor is at start column on an intermediate line within range
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        let l:expected = { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 8, 1), l:expected)
+    End
+
+    It should trigger diagnostic when cursor is at end column on an intermediate line within range
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        let l:expected = { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 8, 15), l:expected)
+    End
+
+    It should trigger diagnostic when cursor is exactly at end position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        let l:expected = { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 9, 5), l:expected)
+    End
+
+    It should not trigger diagnostic when cursor is at line after end position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 10, 5), {})
+    End
+
+    It should not return diagnostic when cursor is one character after end position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 9, 6), {})
+    End
+
+    It should return the closest diagnostic when multiple diagnostics exist across different ranges
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 10, 'line': 4}, 'end': {'character': 7, 'line': 10}} },
+            \     { 'range': {'start': {'character': 12, 'line': 6}, 'end': {'character': 5, 'line': 8}} }
+            \   ]
+        let l:expected = { 'range': {'start': {'character': 10, 'line': 4}, 'end': {'character': 7, 'line': 10}} }
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 7, 3), l:expected)
+    End
+
+    It should return the most specific diagnostic when multiple diagnostics overlap at cursor position
+        let l:diagnostics = [
+            \     { 'range': {'start': {'character': 10, 'line': 4}, 'end': {'character': 15, 'line': 4}} },
+            \     { 'range': {'start': {'character': 12, 'line': 4}, 'end': {'character': 14, 'line': 4}} }
+            \   ]
+        let l:expected = { 'range': {'start': {'character': 12, 'line': 4}, 'end': {'character': 14, 'line': 4}} }
+        Assert Equals(lsp#internal#diagnostics#under_cursor#_get_closest_diagnostic(l:diagnostics, 5, 13), l:expected)
+    End
+End

test/testproject-go/documentdiagnositcs.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func documentdiagnostics() {
+	msg := "msg"
+	fmt.Printf(msg +
+		msg +
+		msg,
+	)
+}