Add GitLab templates for issues and merge requests

This patch adds GitLab templates for bug reports, feature and merge requests.

This closes #2117.

3 files changed, 102 insertions, 0 deletions

diff --git a/.gitlab/issue_templates/Bug Report.md b/.gitlab/issue_templates/Bug Report.md
new file mode 100644
index 000000000..0c49b0fe3
--- /dev/null
+++ b/.gitlab/issue_templates/Bug Report.md
@@ -0,0 +1,69 @@
+<!--
+Please read this!
+
+Before opening a new issue, make sure to search for keywords in the issues
+filtered by "bug::confirmed" or "bug::unconfirmed" and "bugzilla" label:
+
+- https://gitlab.com/libeigen/eigen/-/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=bug%3A%3Aconfirmed
+- https://gitlab.com/libeigen/eigen/-/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=bug%3A%3Aunconfirmed
+- https://gitlab.com/libeigen/eigen/-/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=bugzilla
+
+and verify the issue you're about to submit isn't a duplicate. -->
+
+### Summary
+<!-- Summarize the bug encountered concisely. -->
+
+### Environment
+<!-- Please provide your development environment here -->
+- **Operating System** : Windows/Linux
+- **Architecture** : x64/Arm64/PowerPC ...
+- **Eigen Version** : 3.3.9
+- **Compiler Version** : Gcc7.0
+- **Compile Flags** : -O3 -march=native
+- **Vector Extension** : SSE/AVX/NEON ...
+
+### Minimal Example
+<!-- If possible, please create a minimal example here that exhibits the problematic behavior.
+You can also link to [godbolt](https://godbolt.org). But please note that you need to click 
+the "Share" button in the top right-hand corner of the godbolt page where you reproduce the sample 
+code to get the share link instead of in your browser address bar. 
+
+You can read [the guidelines on stackoverflow](https://stackoverflow.com/help/minimal-reproducible-example)
+on how to create a good minimal example. -->
+
+```cpp
+//show your code here
+```
+
+### Steps to reproduce
+<!-- Describe how one can reproduce the issue - this is very important. Please use an ordered list. -->
+
+1. first step
+2. second step
+3. ... 
+
+### What is the current *bug* behavior?
+<!-- Describe what actually happens. -->
+
+### What is the expected *correct* behavior?
+<!-- Describe what you should see instead. -->
+
+### Relevant logs
+<!-- Add relevant code snippets or program output within blocks marked by " ``` " -->
+
+<!-- OPTIONAL: remove this section if you are not reporting a compilation warning issue.-->
+### Warning Messages
+<!-- Show us the warning messages you got! -->
+
+<!-- OPTIONAL: remove this section if you are not reporting a performance issue. -->
+### Benchmark scripts and results
+<!-- Please share any benchmark scripts - either standalone, or using [Google Benchmark](https://github.com/google/benchmark). -->
+
+### Anything else that might help
+<!-- It will be better to provide us more information to help narrow down the cause. 
+Including but not limited to the following: 
+- lines of code that might help us diagnose the problem. 
+- potential ways to address the issue.
+- last known working/first broken version (release number or commit hash). --> 
+
+- [ ] Have a plan to fix this issue.
diff --git a/.gitlab/issue_templates/Feature Request.md b/.gitlab/issue_templates/Feature Request.md
new file mode 100644
index 000000000..2c6f908af
--- /dev/null
+++ b/.gitlab/issue_templates/Feature Request.md
@@ -0,0 +1,7 @@
+### Describe the feature you would like to be implemented.
+
+### Would such a feature be useful for other users? Why?
+
+### Any hints on how to implement the requested feature?
+
+### Additional resources
diff --git a/.gitlab/merge_request_templates/Merge Request Template.md b/.gitlab/merge_request_templates/Merge Request Template.md
new file mode 100644
index 000000000..3fe963afa
--- /dev/null
+++ b/.gitlab/merge_request_templates/Merge Request Template.md
@@ -0,0 +1,26 @@
+<!-- 
+Thanks for contributing a merge request! Please name and fully describe your MR as you would for a commit message.
+If the MR fixes an issue, please include "Fixes #issue" in the commit message and the MR description.
+
+In addition, we recommend that first-time contributors read our [contribution guidelines](https://eigen.tuxfamily.org/index.php?title=Contributing_to_Eigen) and [git page](https://eigen.tuxfamily.org/index.php?title=Git), which will help you submit a more standardized MR.
+
+Before submitting the MR, you also need to complete the following checks:
+- Make one PR per feature/bugfix (don't mix multiple changes into one PR). Avoid committing unrelated changes.
+- Rebase before committing
+- For code changes, run the test suite (at least the tests that are likely affected by the change).
+  See our [test guidelines](https://eigen.tuxfamily.org/index.php?title=Tests).
+- If possible, add a test (both for bug-fixes as well as new features)
+- Make sure new features are documented
+
+Note that we are a team of volunteers; we appreciate your patience during the review process.
+
+Again, thanks for contributing! -->
+
+### Reference issue
+<!-- You can link to a specific issue using the gitlab syntax #<issue number>  -->
+
+### What does this implement/fix?
+<!--Please explain your changes.-->
+
+### Additional information
+<!--Any additional information you think is important.-->