add notice when nothing changed

Author: casaqori

lib/modules/manager/gomod/artifacts.spec.ts

@@ -2304,7 +2304,7 @@ describe('modules/manager/gomod/artifacts', () => {
     ]);
   });
 
-  it('go.mod file contains moder go full version without toolchain and constraint is present', async () => {
+  it('go.mod file contains modern go full version without toolchain and constraint is present', async () => {
     GlobalConfig.set({ ...adminConfig, binarySource: 'install' });
     fs.readLocalFile.mockResolvedValueOnce('Current go.sum');
     fs.readLocalFile.mockResolvedValueOnce(null); // vendor modules filename
@@ -2587,6 +2587,61 @@ describe('modules/manager/gomod/artifacts', () => {
     expect(execSnapshots).toMatchObject(expectedResult);
   });
 
+  it('with config constraint that does not result in any updates', async () => {
+    GlobalConfig.set({ ...adminConfig, binarySource: 'install' });
+    fs.readLocalFile.mockResolvedValueOnce('Current go.sum');
+    fs.readLocalFile.mockResolvedValueOnce(null); // vendor modules filename
+    const execSnapshots = mockExecAll();
+    git.getRepoStatus.mockResolvedValueOnce(
+      partial<StatusResult>({
+        modified: [],
+      }),
+    );
+    fs.readLocalFile
+      .mockResolvedValueOnce('Current go.sum')
+      .mockResolvedValueOnce(`someText\n\ngo 1.23.6\n\n${gomod1}`);
+
+    datasource.getPkgReleases.mockResolvedValueOnce({
+      releases: [
+        { version: '1.23.0' },
+        { version: '1.23.6' },
+        { version: '1.24.1' },
+      ],
+    });
+
+    const res = await gomod.updateArtifacts({
+      packageFileName: 'go.mod',
+      updatedDeps: [{ depName: 'golang.org/x/crypto', newVersion: '0.35.0' }],
+      newPackageFileContent: `someText\n\ngo 1.23.6\n\n${gomod1}`,
+      config: {
+        updateType: 'minor',
+        constraints: {
+          go: '1.23',
+        },
+      },
+    });
+
+    expect(res).toEqual([
+      {
+        notice: {
+          file: 'go.mod',
+          message:
+            'Updates are constrained to go version 1.23 but the dependency required a more recent version.\nTherefore, the update was discarded.',
+        },
+      },
+    ]);
+
+    expect(execSnapshots).toMatchObject([
+      {
+        cmd: 'install-tool golang 1.23.6',
+      },
+      {
+        cmd: 'go get -t ./... toolchain@none [email protected]',
+        // simulated to result in no changes since no more recent dependency version satisfies the constraint
+      },
+    ]);
+  });
+
   it('returns artifact notices', async () => {
     artifactsExtra.getExtraDepsNotice.mockReturnValue('some extra notice');
     GlobalConfig.set({ ...adminConfig, binarySource: 'docker' });

lib/modules/manager/gomod/artifacts.ts

@@ -238,6 +238,8 @@ export async function updateArtifacts({
           //       because the dependencies' go.mod is not in 'updatedDeps' to determine
           //       which highest version is actually required.
           extraGetArguments.push(`go@${goConstraint}`);
+          // TODO: if we are already at latest compatible version, then renovate still bumps it
+          //        instead the PR should be erroring out!!
         }
       }
     }
@@ -386,7 +388,25 @@ export async function updateArtifacts({
 
     await exec(execCommands, execOptions);
 
+    const res: UpdateArtifactsResult[] = [];
     const status = await getRepoStatus();
+    if (
+      status.modified.length === 0 &&
+      updatedDeps.length > 0 &&
+      config.constraints?.go
+    ) {
+      const downgradeNotice = `Updates are constrained to go version ${config.constraints.go} but the dependency required a more recent version.\nTherefore, the update was discarded.`;
+
+      logger.debug('Returning no update warning');
+      res.push({
+        notice: {
+          file: goModFileName,
+          message: downgradeNotice,
+        },
+      });
+
+      return res;
+    }
     if (
       !status.modified.includes(sumFileName) &&
       !status.modified.includes(goModFileName) &&
@@ -395,7 +415,6 @@ export async function updateArtifacts({
       return null;
     }
 
-    const res: UpdateArtifactsResult[] = [];
     if (status.modified.includes(sumFileName)) {
       logger.debug('Returning updated go.sum');
       res.push({