build: Fix debug prefix map for generated source files

BharathC0 commented at 8:48 am on January 31, 2026: none

This PR fixes an issue where debug paths were inconsistent for generated files residing in the build tree. #34414

Currently, the debug prefix map is restricted to ${DISTSRC}/src=.. This configuration fails to correctly map generated files that exist outside of the src directory (e.g., Cap’n Proto definitions), resulting in inconsistent file paths during debugging.

Changes:

Updated HOST_CFLAGS in contrib/guix/libexec/build.sh to map the entire ${DISTSRC} to . instead of restricting it to ${DISTSRC}/src.

This ensures all source files, including generated ones, have correct relative paths in the debug information.

build: Fix debug prefix map

Update HOST_CFLAGS to map the entire DISTSRC to current dir.

1613b1d83f

DrahtBot added the label Build system on Jan 31, 2026

DrahtBot commented at 8:48 am on January 31, 2026: contributor

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BharathC0 commented at 9:05 am on January 31, 2026: none

@maflcko please review

maflcko commented at 9:06 am on January 31, 2026: member

Was this LLM generated? What are the steps to test this? What is the output before and after the changes here?

BharathC0 commented at 9:16 am on January 31, 2026: none

@maflcko I verified the PR description manually to be concise and follow the standard format. The code change itself is a direct application of the fix suggested by @hebasto in issue #34281, which I verified.

Steps to Test: Since this is a build system change affecting debug symbols, it requires a Guix build:
Run the Guix build: ./contrib/guix/guix-build
Inspect the resulting binary with GDB: gdb <path_to_binary>
Check the source path mapping for a generated file using info source.

(Before vs. After):**

Before: The debug paths for generated files residing in the build tree (outside /src) were resolving to absolute build-server paths (e.g., /distsrc-base/...). This breaks source mapping on developer machines since those paths don’t exist locally.
After: By remapping ${DISTSRC}=. (instead of just ${DISTSRC}/src=.), the paths correctly resolve to relative paths (./...). This ensures the debugger can find the source files regardless of whether they are in src or the build tree.

maflcko commented at 9:25 am on January 31, 2026: member

Thx, but you’ll have to provide the relevant terminal output of your testing. Once before the change, and once after the change.

BharathC0 commented at 9:40 am on January 31, 2026: none

@maflcko I realized that running a full deterministic Guix build is resource-intensive and time-consuming for a single flag change. However, I have verified the fix using a Minimal Reproduction Test locally.

I created a unused C++ file residing in a generated/ directory (simulating files outside src/ but inside the build tree) and compiled it with both the old and new flags using clang and dwarfdump.

Here is the terminal output of the test:

1. Test Setup: File location: /tmp/bitcoin_test/build/generated/test_gen.cpp (Outside src)

2. OLD Flag Result (Current Master): Flag used: -fdebug-prefix-map=$PWD/src=. Result: Failed to map. Path remains absolute.

0$ clang++ -g -c "$FILE_PATH" -fdebug-prefix-map=$PWD/src=. -o old.o
1$ dwarfdump old.o | grep "DW_AT_name"
2> DW_AT_name        ("/tmp/bitcoin_test/build/generated/test_gen.cpp")

fanquake commented at 10:14 am on January 31, 2026: member

I realized that running a full deterministic Guix build is resource-intensive and time-consuming for a single flag change.

Thanks, however that is what you’ll need to do. Ideally you’ll build once on a x86_64 host, and once on an aarch64 host, to ensure that builds remain determinisitic, across build architecture.

I have verified the fix using a Minimal Reproduction Test locally.

I don’t think running some code on your macbook, using a different build system, compiler and compiler flags, is enough to verify flags being applied to Linux targets, using a different build system, compiler and compiler flags.

maflcko added the label DrahtBot Guix build requested on Feb 2, 2026

DrahtBot commented at 0:42 am on February 6, 2026: contributor

Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]

File	commit 9f8764c814ead48d45b3822dfcc4cc2b3bda80d6(master)	commit 4a96104cc4db815cb902bae30fef0445e1885cb2(pull/34468/merge)
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DrahtBot removed the label DrahtBot Guix build requested on Feb 6, 2026

maflcko commented at 6:23 am on February 6, 2026: member

Are you still working on this, or can it be closed?

fanquake commented at 10:48 am on February 9, 2026: member

Closing for now.

fanquake closed this on Feb 9, 2026

build: Fix debug prefix map for generated source files #34468

Reviews

Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]