build: enhance FYPP error messaging and add defensive checks in stdlib.cmake by srinjoy933 · Pull Request #1137 · fortran-lang/stdlib

srinjoy933 · 2026-03-04T07:47:57Z

Solves #1136
This PR enhances the developer onboarding experience by replacing generic build failures with actionable diagnostic messages. While setting up the environment on Windows 11, I found that a missing fypp in the system PATH (common with pip installs) leads to a "silent failure" .

Changes:

Actionable Errors: Updated the root CMakeLists.txt to suggest specific fixes, including checking the Python Scripts folder and using the -DFYPP_EXECUTABLE flag.

Defensive Programming: Added a guard clause in cmake/stdlib.cmake to validate the preprocessor path before generating build commands, preventing "empty command" errors.

srinjoy933 · 2026-03-04T09:45:46Z

@jvdp1 @jalvesz please kindly review this pr ,and please kindly let me know if there are any scope of changes or modifications according to you.

srinjoy933 · 2026-03-04T18:05:31Z

Thank you for the detailed feedback, @jalvesz. I completely agree with your point regarding the separation of responsibilities; the build system should provide diagnostic tools rather than assuming a specific installation path, especially given the variety of environments like Conda, MSYS2, or standard Python installs.

I will fix the accidental logic flip in cmake/stdlib.cmake to ensure the message correctly displays 'Disable' when a module is not compiled.

I will update the CMakeLists.txt error message to remove the specific Windows roaming paths. Instead, I will include the where (Windows) and which (Linux/macOS) commands you suggested to help users verify their own environments.

I will keep the instruction for the -DFYPP_EXECUTABLE flag, as it remains the standard way for users to manually point to the preprocessor if the automatic search fails.

Please let me know @jalvesz if this plan aligns with your expectations. Once you confirm, I will push the updated commits to this PR.

srinjoy933 · 2026-03-04T18:40:33Z

Sorry by mistake i made a commit with a wrong comment written in it , I changed that and the commit named"Final Changes" is the correct one .Kindly please review this one @jalvesz

codecov · 2026-03-06T07:27:10Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.99%. Comparing base (e33b3eb) to head (98d075e).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1137   +/-   ##
=======================================
  Coverage   67.99%   67.99%           
=======================================
  Files         404      404           
  Lines       12935    12935           
  Branches     1392     1392           
=======================================
  Hits         8795     8795           
  Misses       4140     4140

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

jvdp1

Overall it looks good to me. Here are some suggestions.

jvdp1 · 2026-03-12T07:20:39Z

    # Detect ILP64 (common function)
    function(detect_ilp64 lib_name)
      set(${lib_name}_ILP64 False PARENT_SCOPE)
-      # Prefer checking BLA_SIZEOF_INTEGER (available in CMake >= 3.22)


Why did you remove these two comments? They seem useful to me.

jvdp1 · 2026-03-12T07:21:36Z

-if(NOT FYPP)
-  message(FATAL_ERROR "Preprocessor fypp not found! Please install fypp following the instructions in https://fypp.readthedocs.io/en/stable/fypp.html#installing")
+if(NOT FYPP OR "${FYPP}" MATCHES "NOTFOUND")
+  message(STATUS "Checking for fypp...")


Suggested change

message(STATUS "Checking for fypp...")

What is the goal of this message? I propose to remove it

srinjoy933 · 2026-03-13T21:57:13Z

@jvdp1 @jalvesz I made the changes according to your suggestions , please have a look at it and give me your feedback.

…fix-fypp-error-message :qw :wq

srinjoy933 · 2026-03-20T08:32:53Z

Hey @jvdp1 @jalvesz can you please have a look on this pr and kindly suggest me if any changes are required , waiting for your feedback. Thank you!

Copilot

Pull request overview

This PR improves the CMake configuration experience when the fypp preprocessor is missing by adding clearer diagnostics and a defensive guard in the preprocessing pipeline to avoid later-stage “empty command” build failures.

Changes:

Enhance the top-level CMake failure message for missing fypp with actionable diagnostic steps.
Add a defensive check in cmake/stdlib.cmake to fail early if the preprocessor command/path is invalid.
Minor formatting/comment cleanup in CMake files.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
`CMakeLists.txt`	Improves `fypp`-missing fatal error messaging and adjusts formatting.
`cmake/stdlib.cmake`	Adds a guard in `preprocess()` to prevent invalid/empty custom command invocations; minor whitespace/comment tweaks.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-03-22T16:18:09Z

+    "   Windows:      'where fypp' and 'where python'\n"
+    "   Linux/macOS:  'which fypp' and 'which python'\n\n"
+    " Ensure the executable is in your PATH or set it manually during configuration:\n"
+    "   cmake -B build -DFYPP_EXECUTABLE=/path/to/fypp\n"


The error message instructs users to pass -DFYPP_EXECUTABLE=..., but this project actually uses the FYPP variable from find_program(FYPP fypp) (and cmake/stdlib.cmake calls preprocess("${FYPP}" ...)). As written, the suggested flag won’t have any effect and may further confuse users; align the hint with the actual cache variable (e.g., -DFYPP=/path/to/fypp) or switch the build to consistently use a FYPP_EXECUTABLE cache variable.

Suggested change

" cmake -B build -DFYPP_EXECUTABLE=/path/to/fypp\n"

" cmake -B build -DFYPP=/path/to/fypp\n"

Copilot · 2026-03-22T16:18:09Z

    set(LIB_MOD_DIR ${CMAKE_CURRENT_BINARY_DIR}/mod_files/${target_name}/)
-    #set(INSTALL_MOD_DIR "${CMAKE_INSTALL_MODULEDIR}/${target_name}")
    set(INSTALL_MOD_DIR "${CMAKE_INSTALL_MODULEDIR}")
+


There’s trailing whitespace on this blank line (the file has a whitespace-only line after set(INSTALL_MOD_DIR ...)). .editorconfig enforces trim_trailing_whitespace = true for *.cmake, so this should be removed to avoid style/lint issues.

Suggested change

jvdp1

Thank you @srinjoy933 . I left only one minor comment. Otherwise, I think it is ready to be merged.

jvdp1 · 2026-03-22T16:17:39Z

      # Prefer checking BLA_SIZEOF_INTEGER (available in CMake >= 3.22)
      if(DEFINED BLA_SIZEOF_INTEGER AND BLA_SIZEOF_INTEGER EQUAL 8)
        set(${lib_name}_ILP64 True PARENT_SCOPE)
-      # Fallback: Check BLA_VENDOR manually for signs of ILP64


Please re-insert this comment. It seems usefull to me

srinjoy933 · 2026-03-23T11:24:33Z

hey @jvdp1 I made the change that you have suggested .Please have a look is it fine now.

build: enhance fypp error messaging for better onboarding

101f14f

jalvesz reviewed Mar 4, 2026

View reviewed changes

Comment thread cmake/stdlib.cmake Outdated

Comment thread CMakeLists.txt

srinjoy933 requested a review from jalvesz March 4, 2026 18:28

srinjoy933 added 2 commits March 5, 2026 00:04

address reviewer feedback: simplify error message and fix logic typo

4591fd2

Final changes

f90a2d9

jvdp1 reviewed Mar 12, 2026

View reviewed changes

Suggested Changes

8ef8a19

srinjoy933 requested a review from jvdp1 March 13, 2026 21:55

Merge branch 'master' of https://github.com/fortran-lang/stdlib into …

180e38d

…fix-fypp-error-message :qw :wq

jvdp1 requested a review from Copilot March 22, 2026 16:16

Copilot started reviewing on behalf of jvdp1 March 22, 2026 16:16 View session

Copilot AI reviewed Mar 22, 2026

View reviewed changes

jvdp1 approved these changes Mar 22, 2026

View reviewed changes

updated

98d075e

srinjoy933 requested a review from jvdp1 March 23, 2026 11:23

jalvesz approved these changes Mar 23, 2026

View reviewed changes

jalvesz merged commit ac98d3b into fortran-lang:master Mar 24, 2026
77 checks passed

	" cmake -B build -DFYPP_EXECUTABLE=/path/to/fypp\n"
	" cmake -B build -DFYPP=/path/to/fypp\n"

Conversation

srinjoy933 commented Mar 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

srinjoy933 commented Mar 4, 2026

Uh oh!

Uh oh!

Uh oh!

srinjoy933 commented Mar 4, 2026

Uh oh!

srinjoy933 commented Mar 4, 2026

Uh oh!

codecov Bot commented Mar 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

jvdp1 left a comment

Choose a reason for hiding this comment

Uh oh!

jvdp1 Mar 12, 2026

Choose a reason for hiding this comment

Uh oh!

jvdp1 Mar 12, 2026

Choose a reason for hiding this comment

Uh oh!

srinjoy933 Mar 13, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

srinjoy933 commented Mar 13, 2026

Uh oh!

srinjoy933 commented Mar 20, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Mar 22, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 22, 2026

Choose a reason for hiding this comment

Uh oh!

jvdp1 left a comment

Choose a reason for hiding this comment

Uh oh!

jvdp1 Mar 22, 2026

Choose a reason for hiding this comment

Uh oh!

srinjoy933 commented Mar 23, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

srinjoy933 commented Mar 4, 2026 •

edited

Loading

codecov Bot commented Mar 6, 2026 •

edited

Loading