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pre-commit: add hook to ensure Makefiles are indented with tabs #6691

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pre-commit: add hook to ensure Makefiles are indented with tabs #6691

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9 changes: 9 additions & 0 deletions .pre-commit-config.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,15 @@ repos:
language: node
additional_dependencies: ["prettier@3.7.4"]
stages: [manual]
- id: check-makefile-indentation
name: check Makefiles are indented with tabs
description: ensures that Makefiles are indented with tabs
entry: ./scripts/check_makefiles_for_tabs.sh
language: system
files: "(?i)^makefile$"
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@gemini-code-assist gemini-code-assist bot Dec 29, 2025

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medium

The regex (?i)^makefile$ will only match a file named Makefile or makefile in the root of the repository. If you ever add Makefiles in subdirectories, they will not be checked. A more flexible pattern would be something like (?i)makefile$, which would match any file ending in makefile (e.g., src/Makefile). Consider if you want to support this for future-proofing.

pass_filenames: true # <-- Crucial change: pass filenames to the script
types: [file] # Ensure only regular files are passed, not directories
stages: [manual]
- id: check-zip-file-is-not-committed
name: disallow zip files
description: Zip files are not allowed in the repository
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13 changes: 13 additions & 0 deletions scripts/check_makefiles_for_tabs.sh
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@@ -0,0 +1,13 @@
#!/bin/bash

# Iterate over all files passed as arguments by pre-commit
for makefile in "$@"; do
# Check if the file exists and is a regular file
if [[ -f "$makefile" ]]; then
if grep -P '^\s' "$makefile" | grep -vP '^\t' > /dev/null; then
echo "Error: File '$makefile' contains spaces at the beginning of lines instead of tabs."
exit 1
fi
fi
Comment on lines +6 to +11
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@gemini-code-assist gemini-code-assist bot Dec 29, 2025

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high

This script has a couple of issues:

  1. Portability: The use of grep -P for Perl-compatible regular expressions is a GNU extension and is not available on all systems, notably default macOS installations. This will cause the hook to fail for Mac users.
  2. Redundancy & Efficiency: The if [[ -f "$makefile" ]] check is redundant because pre-commit is configured with types: [file], which ensures only existing files are passed. Additionally, using a pipe with two grep processes is less efficient than a single grep.

You can address these points by using a single, more portable grep command to check for lines starting with a space. The [ ] syntax for a space is used for clarity and portability.

Suggested change
if [[ -f "$makefile" ]]; then
if grep -P '^\s' "$makefile" | grep -vP '^\t' > /dev/null; then
echo "Error: File '$makefile' contains spaces at the beginning of lines instead of tabs."
exit 1
fi
fi
if grep -q '^[ ]' "$makefile"; then
echo "Error: File '$makefile' contains spaces at the beginning of lines instead of tabs."
exit 1
fi

done
exit 0
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