fix bounds panic messages

[cpunion]

Summary

• preserve failing bounds operands and signedness in generated bounds checks
• route slice/string bounds failures through runtime boundsError messages with len/cap-specific codes
• add stable test/go coverage for bounds panic text and un-xfail fixed GOROOT issue30116 cases

GOROOT note

Full GOROOT CI is slow/disabled locally, so I ran targeted fixedbugs cases only. Machine GOROOT: /opt/homebrew/Cellar/go@1.24/1.24.11/libexec (go1.24.11 darwin/arm64). Normal PR CI should run from the fork branch.

Test/go coverage

Added test/go/bounds_panic_text_test.go covering runtime.Error panic text for signed/unsigned index checks, slice/string/array slicing, len vs capacity wording, and full slice max bounds.

Targeted commands run

• go test ./test/go -run TestBoundsPanicText -count=1 -v
• go test ./test/go -run 'Test(BoundsPanicText|UnsignedIndexBoundsCheck|FullSliceBoundsPanicText)' -count=1 -v\n- go run ./cmd/llgo test -run TestBoundsPanicText -count=1 ./test/go\n- go run ./cmd/llgo test -run 'Test(BoundsPanicText|UnsignedIndexBoundsCheck|FullSliceBoundsPanicText)' -count=1 ./test/go\n- go test ./ssa -run 'TestFromTestdata/utf8|TestFromTestgo/cursor' -count=1\n- go test ./ssa -run Test -count=1\n- go test ./cl -run 'TestRunAndTestFrom(Testgo|Testrt|Testdata|Testlibc)' -count=1\n- go test ./test/goroot -run TestGoRootRunCases -count=1 -v -args -goroot "$(go env GOROOT)" -dirs fixedbugs -case '^fixedbugs/issue30116(u)?\.go$' -xfail /tmp/llgo-no-xfail.yaml -run-timeout 5m -build-timeout 3m\n- go test ./test/goroot -run TestGoRootRunCases -count=1 -v -args -goroot "$(go env GOROOT)" -dirs fixedbugs -case '^fixedbugs/issue30116(u)?\.go$' -run-timeout 5m -build-timeout 3m\n\n## Local note\nA direct go test ./runtime/internal/runtime -count=1 is not applicable in this module layout; that runtime path is validated through LLGo test/go, SSA/CL checks, and the targeted GOROOT run.

2026-05-24 issue15002 update

• Classified fixedbugs/issue15002.go as bounds/index load ordering coverage: it protects the final byte of a readable page and expects the x[1] bounds panic before any widened byte load can cross into the protected page.
• Added test/go/bounds_load_order_test.go with mmap/mprotect coverage for uint16/uint32/uint64 byte assembly using both constant and variable indexes.
• Removed only the fixedbugs/issue15002.go linux/amd64 xfail now covered by test/go.
• Local limitation: this machine is darwin/arm64 and Docker is unavailable, so the exact linux/amd64 goroot run is left to CI. I did run the focused goroot case through a temporary GOARCH=amd64 baseline wrapper plus native LLGo explicit-file execution, and the case passed locally.

Additional commands run:

• go test ./test/go -run TestBoundsCheckBeforeWiderByteLoad -count=1 -v
• go run ./cmd/llgo test -run TestBoundsCheckBeforeWiderByteLoad -count=1 ./test/go
• go test ./test/go -count=1
• go test ./test/goroot -run TestGoRootRunCases -count=1 -v -args -goroot "$(go env GOROOT)" -go /tmp/go-amd64-wrapper-llgo-bounds -llgo /tmp/llgo-bounds-issue15002 -dirs fixedbugs -case '^fixedbugs/issue15002.go$' -run-timeout=30s -build-timeout=3m
• go test ./ssa -count=1
• go test ./cl -count=1
• go test ./runtime/internal/runtime -count=1 (not applicable: package is not in the main module)

[cpunion]

PR #1901 follow-up for head b072c41.

Root cause: the failing test (ubuntu-latest, 19) job failed in cl at TestRunAndTestFromTestlibgo/mapzero. The runtime/compiler change now reports the precise Go-style bounds panic runtime error: index out of range [0] with length 0, but cl/_testlibgo/mapzero/expect.txt still expected the old shorter runtime error: index out of range.

Fix: updated the mapzero golden output to match the new bounds panic message. The functional bounds-message coverage remains in test/go/bounds_panic_text_test.go.

Local tests run:

• go test ./test/go -run TestBoundsPanicText -count=1
• go test ./cl -run 'TestRunAndTestFromTestlibgo/mapzero' -count=1\n- go test ./test/go -count=1\n- go test ./ssa -run 'Test.*' -count=1\n- go test ./cl -run TestRunAndTestFromTestlibgo -count=1\n\nCI status: new head checks have started and are currently pending/queued; I am monitoring run set for b072c41.

[codecov-commenter]

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[cpunion]

Index0 follow-up for 525647b:

• Classification: reproduced on xgo-dev/main with xfail disabled using go1.24.11 darwin/arm64. The failure is a GOROOT index0.go runoutput stderr mismatch: llgo panics with type assertion interface{} -> error failed while the upstream harness expects the recovered bounds panic to implement error and contain out of range. This is the same bounds/index panic value/message root as this PR.
• Change: removed only the covered index0.go runoutput xfails for darwin/arm64 and linux/amd64.
• Coverage: test/go/bounds_panic_text_test.go covers runtime.Error panic values and exact Go-compatible bounds/index/slice panic text; the focused GOROOT index0.go case now passes with the default xfail file.
• Xfail scan: no remaining index0/bounds/index xfail entries found after this removal.
• Not covered by this PR: GC/liveness/finalizer/goroutine and nil/chan/print/recover areas remain intentionally untouched. Direct go test ./runtime/... is not applicable in this module layout; runtime behavior is covered through test/go plus ssa/cl and focused GOROOT runs.

Local commands run:

• go test ./test/goroot -run TestGoRootRunCases -count=1 -args -goroot "/opt/homebrew/Cellar/go@1.24/1.24.11/libexec" -dirs . -case '^index0.go$' -directive-mode ci -xfail test/goroot/no-such-xfail.yaml -progress=0
• go test ./test/goroot -run TestGoRootRunCases -count=1 -args -goroot "/opt/homebrew/Cellar/go@1.24/1.24.11/libexec" -dirs . -case '^index0.go$' -directive-mode ci -progress=0
• go test ./test/go -count=1
• go test ./ssa ./cl -count=1
• go test ./runtime/... -count=1 (not applicable: module does not contain package github.com/goplus/llgo/runtime)

[cpunion]

Update for issue15002 bounds load ordering coverage:

• Classified fixedbugs/issue15002.go as in-scope bounds/index load ordering coverage. The test guards a page boundary and expects the x[1] bounds panic before any widened byte load crosses into the protected page.
• Added test/go/bounds_load_order_test.go covering uint16/uint32/uint64 byte assembly with constant and variable indexes.
• Removed only the fixedbugs/issue15002.go linux/amd64 xfail.
• Local limitation: exact linux/amd64 goroot execution is left to CI because this machine is darwin/arm64 and Docker is unavailable. Local focused goroot execution via GOARCH=amd64 baseline wrapper plus native LLGo explicit-file run passed.

Additional local results: go test ./test/go -count=1 PASS; go test ./ssa -count=1 PASS; go test ./cl -count=1 PASS; direct go test ./runtime/internal/runtime is not applicable in this module layout.