doc: update llvm based coverage example
What the developer wrote
Authored by Max Edwards
doc: update llvm based coverage example
On some systems the old example of using xargs to pass list of profraw
files can exceed xargs's argument limit resulting in multiple executions
of llvm-profdata merge command which overwrites it's output file losing
coverage information. Switch to using a file with a list of filenames.
What changed, and why it matters
This commit only updates a documentation example for developers about how to merge code-coverage data files. It changes the suggested shell command from using xargs to using a file list, preventing a tool from running multiple times and accidentally overwriting its own output. There is no change to Bitcoin Core's actual code, network behavior, or wallet security.
No security action needed. This is a documentation-only quality improvement for developer tooling.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The diff modifies doc/developer-notes.md. The LLVM coverage workflow example now writes the list of .profraw files to a text file and passes it to llvm-profdata merge via the -f flag, instead of piping through xargs. This avoids argument-length limits that could split the merge into multiple invocations and overwrite build/coverage.profdata. No source code, build scripts, tests, or consensus logic are touched.
Changed components
doc/developer-notes.mdInspect captured patch +2 / −1
diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index 18691811..bd1431e7 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -457,7 +457,8 @@ LLVM_PROFILE_FILE="$(pwd)/build/raw_profile_data/%m_%p.profraw" ctest --test-dir
LLVM_PROFILE_FILE="$(pwd)/build/raw_profile_data/%m_%p.profraw" build/test/functional/test_runner.py # Append "-j N" here for N parallel jobs
# Merge all the raw profile data into a single file
-find build/raw_profile_data -name "*.profraw" | xargs llvm-profdata merge -o build/coverage.profdata
+find build/raw_profile_data -name "*.profraw" > build/raw_profile_data_files.txt
+llvm-profdata merge -f build/raw_profile_data_files.txt -o build/coverage.profdata
```
> **Note:** The "counter mismatch" warning can be safely ignored, though it can be resolved by updating to Clang 19.
Why this scored 15/100
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