From 8aae70026da3769bf16530aa513ffedeb95dd84c Mon Sep 17 00:00:00 2001
From: Snoweuph <snow@euph.email>
Date: Sun, 1 Feb 2026 04:11:10 +0100
Subject: [PATCH] language/go: add `golangci-lint` for extra diagnostics
 (#1376)

---
 docs/manual/release-notes/rl-0.9.md |   2 +
 modules/plugins/languages/go.nix    | 105 +++++++++++++++++++++++++++-
 2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/docs/manual/release-notes/rl-0.9.md b/docs/manual/release-notes/rl-0.9.md
index 08a5cc63..e31a07e8 100644
--- a/docs/manual/release-notes/rl-0.9.md
+++ b/docs/manual/release-notes/rl-0.9.md
@@ -164,6 +164,8 @@
 - Added [tera](https://keats.github.io/tera/) language support (syntax
   highlighting only).
 
+- Added [`golangci-lint`](https://golangci-lint.run/) for more diagnostics.
+
 [vagahbond](https://github.com/vagahbond): [codewindow.nvim]:
 https://github.com/gorbit99/codewindow.nvim
 
diff --git a/modules/plugins/languages/go.nix b/modules/plugins/languages/go.nix
index c51077f9..bfaafd0d 100644
--- a/modules/plugins/languages/go.nix
+++ b/modules/plugins/languages/go.nix
@@ -10,7 +10,7 @@
   inherit (lib.meta) getExe;
   inherit (lib.generators) mkLuaInline;
   inherit (lib.types) bool enum package;
-  inherit (lib.nvim.types) mkGrammarOption deprecatedSingleOrListOf;
+  inherit (lib.nvim.types) mkGrammarOption diagnostics deprecatedSingleOrListOf;
   inherit (lib.nvim.dag) entryAfter;
   inherit (lib.nvim.attrsets) mapListToAttrs;
 
@@ -78,6 +78,91 @@
       package = pkgs.delve;
     };
   };
+
+  defaultDiagnosticsProvider = ["golangci-lint"];
+  diagnosticsProviders = {
+    golangci-lint = let
+      pkg = pkgs.golangci-lint;
+    in {
+      package = pkg;
+      config = {
+        cmd = getExe pkg;
+        args = [
+          "run"
+          "--output.json.path=stdout"
+          "--issues-exit-code=0"
+          "--show-stats=false"
+          "--fix=false"
+          "--path-mode=abs"
+          # Overwrite values that could be configured and result in unwanted writes
+          "--output.text.path="
+          "--output.tab.path="
+          "--output.html.path="
+          "--output.checkstyle.path="
+          "--output.code-climate.path="
+          "--output.junit-xml.path="
+          "--output.teamcity.path="
+          "--output.sarif.path="
+        ];
+        parser = mkLuaInline ''
+          function(output, bufnr)
+            local SOURCE = "golangci-lint";
+
+            local function display_tool_error(msg)
+              return{
+                {
+                  bufnr = bufnr,
+                  lnum = 0,
+                  col = 0,
+                  message = string.format("[%s] %s", SOURCE, msg),
+                  severity = vim.diagnostic.severity.ERROR,
+                  source = SOURCE,
+                },
+              }
+            end
+
+            if output == "" then
+              return display_tool_error("no output provided")
+            end
+
+            local ok, decoded = pcall(vim.json.decode, output)
+            if not ok then
+              return display_tool_error("failed to parse JSON output")
+            end
+
+            if not decoded or not decoded.Issues then
+              return display_tool_error("unexpected output format")
+            end
+
+            local severity_map = {
+              error   = vim.diagnostic.severity.ERROR,
+              warning = vim.diagnostic.severity.WARN,
+              info    = vim.diagnostic.severity.INFO,
+              hint    = vim.diagnostic.severity.HINT,
+            }
+            local diagnostics = {}
+            for _, issue in ipairs(decoded.Issues) do
+              local sev = vim.diagnostic.severity.ERROR
+              if issue.Severity and issue.Severity ~= "" then
+                local normalized = issue.Severity:lower()
+                sev = severity_map[normalized] or vim.diagnostic.severity.ERROR
+              end
+              table.insert(diagnostics, {
+                bufnr = bufnr,
+                lnum = issue.Pos.Line - 1,
+                col = issue.Pos.Column - 1,
+                message = issue.Text,
+                code = issue.FromLinter,
+                severity = sev,
+                source = SOURCE,
+              })
+            end
+            return diagnostics
+          end
+        '';
+      };
+    };
+  };
 in {
   options.vim.languages.go = {
     enable = mkEnableOption "Go language support";
@@ -134,6 +219,14 @@ in {
         default = debuggers.${cfg.dap.debugger}.package;
       };
     };
+    extraDiagnostics = {
+      enable = mkEnableOption "extra Go diagnostics" // {default = config.vim.languages.enableExtraDiagnostics;};
+      types = diagnostics {
+        langDesc = "Go";
+        inherit diagnosticsProviders;
+        inherit defaultDiagnosticsProvider;
+      };
+    };
   };
 
   config = mkIf cfg.enable (mkMerge [
@@ -179,5 +272,15 @@ in {
         debugger.nvim-dap.enable = true;
       };
     })
+
+    (mkIf cfg.extraDiagnostics.enable {
+      vim.diagnostics.nvim-lint = {
+        enable = true;
+        linters_by_ft.go = cfg.extraDiagnostics.types;
+        linters =
+          mkMerge (map (name: {${name} = diagnosticsProviders.${name}.config;})
+            cfg.extraDiagnostics.types);
+      };
+    })
   ]);
 }