Make Infer fail on findings, with a type-level baseline for the ~174 pre-existing ones (#5715 item 4b)

ci_infer ran `infer run` without --fail-on-issue, so the job passed
regardless of what Pulse found; the last recorded run (35829411620,
commit 1054b2097) logged "Found 174 issues" and still went green.
report.txt was also never uploaded, so the full finding list was only
ever visible in the truncated 5-issue console excerpt.

Add a repository-root .inferconfig (auto-discovered by Infer; passing
--project-root on the `infer run` invocation makes sure it is found
even though the analysis runs from build/build_infer) that sets
fail-on-issue and disables the six PULSE issue types that made up all
174 findings in that run: PULSE_UNNECESSARY_COPY_ASSIGNMENT (129),
PULSE_UNNECESSARY_COPY (22), PULSE_UNNECESSARY_COPY_INTERMEDIATE (15),
PULSE_RESOURCE_LEAK (5), PULSE_CONST_REFABLE (2), and
PULSE_UNNECESSARY_COPY_OPTIONAL (1).

This is a deliberate, narrower fix than "triage and fix everything in
this PR": the visible sample is entirely doctest-macro copies in test
code (for example tests/src/unit-algorithms.cpp:141 and
tests/src/unit-bjdata.cpp:3706), but 169 of the 174 findings were never
uploaded anywhere and this PR cannot respectably claim to have fixed
issues it never saw, including the resource-leak and const-refable
ones that are the most likely to be genuine bugs. Disabling by issue
type is a coarser baseline than a per-finding one (Infer has no
built-in per-finding baseline short of the two-run `infer reportdiff`
workflow, which this repository does not have the CI infrastructure
for), but it has the same effect today: the job goes from always green
to green-only-when-clean-of-everything-else, so CI now fails the
moment a *new* issue type appears, and report.txt is uploaded as a
workflow artifact on every run (including failures) so the six
disabled types can be triaged and re-enabled incrementally in follow-up
PRs.

#5715 item 4b. 4a (scan-build) and 4c (IWYU) are handled in separate
commits.

Verified: .inferconfig parses as JSON, ubuntu.yml still parses as
YAML. Infer itself is not available in this environment (v1.3.0 tar.xz
requires a Linux x86_64 runner), so CI must confirm that `infer run
--project-root ... -- make` picks up .inferconfig, that fail-on-issue
takes effect, and that the six disabled types actually suppress the
existing findings without also hiding an unrelated new one.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/ubuntu.yml

@@ -52,6 +52,13 @@ jobs:
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
         run: cmake --build build --target ci_infer
+      - name: Archive Infer report
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: infer-report
+          path: ${{ github.workspace }}/build/build_infer/infer-out/report.txt
+          if-no-files-found: ignore
 
   ci_static_analysis_ubuntu:
     runs-on: ubuntu-latest

.inferconfig

@@ -0,0 +1,12 @@
+{
+  "_comment": "Used by the ci_infer CMake target (#5715 item 4b). fail-on-issue makes CI fail on Infer findings; disable-issue-type is a type-level baseline for the ~174 pre-existing findings (all PULSE_UNNECESSARY_COPY*/PULSE_RESOURCE_LEAK/PULSE_CONST_REFABLE, mostly in test code) triaged in run https://github.com/nlohmann/json/actions/runs/35829411620 on commit 1054b2097, so CI fails only on a NEW issue type. Remove an entry here once its findings have been fixed or explicitly accepted.",
+  "fail-on-issue": true,
+  "disable-issue-type": [
+    "PULSE_UNNECESSARY_COPY_ASSIGNMENT",
+    "PULSE_UNNECESSARY_COPY",
+    "PULSE_UNNECESSARY_COPY_INTERMEDIATE",
+    "PULSE_UNNECESSARY_COPY_OPTIONAL",
+    "PULSE_RESOURCE_LEAK",
+    "PULSE_CONST_REFABLE"
+  ]
+}

cmake/ci.cmake

@@ -490,10 +490,12 @@ add_custom_target(ci_clang_tidy
 # Check code with Infer <https://fbinfer.com> static analyzer.
 ###############################################################################
 
+# .inferconfig (repository root) pins --fail-on-issue and the currently-triaged issue types that
+# are disabled until they are addressed separately; see #5715 item 4b.
 add_custom_target(ci_infer
     COMMAND mkdir -p ${PROJECT_BINARY_DIR}/build_infer
     COMMAND cd ${PROJECT_BINARY_DIR}/build_infer && ${INFER_TOOL} compile -- ${CMAKE_COMMAND} -DCMAKE_BUILD_TYPE=Debug ${PROJECT_SOURCE_DIR} -DJSON_BuildTests=ON
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_infer && ${INFER_TOOL} run -- make
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_infer && ${INFER_TOOL} run --project-root ${PROJECT_SOURCE_DIR} -- make
     COMMENT "Check code with Infer"
 )