Fix GNU LD regex matching CMake status lines as diagnostics (#4910)

[Omotola]

Fix GNU LD diagnostic regex matching CMake status lines (#4910)

Problem

The GNU linker diagnostic parser incorrectly matches informational CMake build output as linker diagnostics. For
example, Zephyr build status lines like:

-- Zephyr version: 4.3.0 (/path/to/zephyr), build: v4.3.0

appear in the VS Code Problems panel as errors with source: cmake GNULD, because the regex .*ld in the pattern
matches the ld suffix in build.

Root Cause

Five regex patterns in src/diagnostics/gnu-ld.ts use .*ld to match the linker binary path. This is too broad — it
matches any word ending in ld (e.g., build, child, ould), not just actual linker paths like /usr/bin/ld or
C:\mingw\bin\ld.exe.

Fix

Changed .ld → (?:.[/\])?ld in all five patterns. This requires ld to either:

• appear at the start of the line, or
• be preceded by a path separator (/ or )

This ensures only real linker binary paths are matched while rejecting arbitrary words that happen to end in ld.

Testing

Added two new unit tests that reproduce the false positive from #4910:

• Zephyr version line: -- Zephyr version:
  4.3.0 (/path/to/zephyr), build: v4.3.0
• Generic CMake status line: -- Some tool version:
  1.0 (/path/to/tool), build: v1.0

Both tests fail before the fix and pass after. All existing GNU LD diagnostic tests continue to pass.

Changes

• src/diagnostics/gnu-ld.ts — Tightened 5 regex patterns
• test/unit-tests/diagnostics.test.ts — Added 2 negative test cases
• CHANGELOG.md — Added bug fix entry

Fixes #4910

[hanniavalera]

hi! nice fix for the Zephyr case. one concern before merge: the new prefix (?:.*[/\\])?ld requires ld to be preceded by /, \, or start-of-line, which drops cross-compiler linkers invoked by bare name (common in Zephyr / ARM bare-metal / Yocto where the toolchain is on PATH):

arm-none-eabi-ld: cannot find -lfoo
aarch64-linux-gnu-ld: warning: cannot find entry symbol _start

These previously matched via .*ld and now silently disappear from the Problems panel. Affects pattern 4 and pattern 5, and also 1/2/3.

suggested tweak: allow - alongside path separators, and constrain the prefix to a filename-like token so sentences can't match:

(?:[^\s:]*[/\\\-])?ld(?:\.exe)?

this still rejects the Zephyr build: line while catching arm-none-eabi-ld: and friends.

also worth adding a positive test next to the new ones in diagnostics.test.ts for arm-none-eabi-ld: so this can't regress again. the existing gnuld tests only cover /path/to/ld[.exe] style inputs, which is how this gap slipped through.