feat(diagnostic): filter diagnostics by specific severities (#24736)

Allow users to filter diagnostics by specifying severities

3 files changed, 28 insertions, 5 deletions

diff --git a/runtime/doc/diagnostic.txt b/runtime/doc/diagnostic.txt
index edbba6ac41..d0aa538011 100644
--- a/runtime/doc/diagnostic.txt
+++ b/runtime/doc/diagnostic.txt
@@ -66,7 +66,7 @@ The "severity" key in a diagnostic is one of the values defined in
     vim.diagnostic.severity.HINT
 
 Functions that take a severity as an optional parameter (e.g.
-|vim.diagnostic.get()|) accept one of two forms:
+|vim.diagnostic.get()|) accept one of three forms:
 
 1. A single |vim.diagnostic.severity| value: >lua
 
@@ -75,8 +75,17 @@ Functions that take a severity as an optional parameter (e.g.
 2. A table with a "min" or "max" key (or both): >lua
 
     vim.diagnostic.get(0, { severity = { min = vim.diagnostic.severity.WARN } })
+<
+    This form allows users to specify a range of severities.
+
+3. A list-like table: >lua
 
-The latter form allows users to specify a range of severities.
+    vim.diagnostic.get(0, { severity = {
+        vim.diagnostic.severity.WARN,
+        vim.diagnostic.severity.INFO,
+    } })
+<
+    This form allows users to filter for specific severities
 
 ==============================================================================
 HANDLERS                                                *diagnostic-handlers*
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index 576c56f408..483e829770 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -145,6 +145,9 @@ The following new APIs and features were added.
 
 • Improved messages for type errors in `vim.api.*` calls (including `opts` params)
 
+• Functions that take a severity as an optional parameter (e.g.
+  |vim.diagnostic.get()|) now also accept a list of severities |vim.diagnostic.severity|
+
 ==============================================================================
 CHANGED FEATURES                                                 *news-changed*
 
diff --git a/runtime/lua/vim/diagnostic.lua b/runtime/lua/vim/diagnostic.lua
index 1391dafd75..96d1cb7629 100644
--- a/runtime/lua/vim/diagnostic.lua
+++ b/runtime/lua/vim/diagnostic.lua
@@ -94,11 +94,22 @@ local function filter_by_severity(severity, diagnostics)
     end, diagnostics)
   end
 
-  local min_severity = to_severity(severity.min) or M.severity.HINT
-  local max_severity = to_severity(severity.max) or M.severity.ERROR
+  if severity.min or severity.max then
+    local min_severity = to_severity(severity.min) or M.severity.HINT
+    local max_severity = to_severity(severity.max) or M.severity.ERROR
+
+    return vim.tbl_filter(function(t)
+      return t.severity <= min_severity and t.severity >= max_severity
+    end, diagnostics)
+  end
+
+  local severities = {}
+  for _, s in ipairs(severity) do
+    severities[to_severity(s)] = true
+  end
 
   return vim.tbl_filter(function(t)
-    return t.severity <= min_severity and t.severity >= max_severity
+    return severities[t.severity]
   end, diagnostics)
 end