-Zindirect-branch-cs-prefix on top of -Zretpoline*

[ojeda]

Cc: @azhogin @Darksonn

This goes on top of #135927, i.e. please skip the first commit here. Please feel free to inherit it there.

In fact, I am not sure if there is any use case for the flag without -Zretpoline*. GCC and Clang allow it, though.

There is a FIXME for two ignores in the test that I took from another test I did in the past -- they may be needed or not here since I didn't run the full CI. Either way, it is not critical.

Tracking issue: #116852.
MCP: rust-lang/compiler-team#868.

[ojeda]

@rustbot label F-target_modifiers A-rust-for-linux

[ojeda]

The error is related to the base PR -- I think this one should be clean (modulo the marked ignore-*s) when that one is.

[rust-log-analyzer]

The job x86_64-gnu-llvm-19 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

#18 exporting to docker image format
#18 sending tarball 20.2s done
#18 DONE 33.2s
##[endgroup]
Setting extra environment values for docker:  --env ENABLE_GCC_CODEGEN=1 --env GCC_EXEC_PREFIX=/usr/lib/gcc/
[CI_JOB_NAME=x86_64-gnu-llvm-19]
[CI_JOB_NAME=x86_64-gnu-llvm-19]
debug: `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` configured.
---
sccache: Listening on address 127.0.0.1:4226
##[group]Configure the build
configure: processing command line
configure: 
configure: build.configure-args := ['--build=x86_64-unknown-linux-gnu', '--llvm-root=/usr/lib/llvm-19', '--enable-llvm-link-shared', '--set', 'rust.randomize-layout=true', '--set', 'rust.thin-lto-import-instr-limit=10', '--set', 'build.print-step-timings', '--enable-verbose-tests', '--set', 'build.metrics', '--enable-verbose-configure', '--enable-sccache', '--disable-manage-submodules', '--enable-locked-deps', '--enable-cargo-native-static', '--set', 'rust.codegen-units-std=1', '--set', 'dist.compression-profile=balanced', '--dist-compression-formats=xz', '--set', 'rust.lld=false', '--disable-dist-src', '--release-channel=nightly', '--enable-debug-assertions', '--enable-overflow-checks', '--enable-llvm-assertions', '--set', 'rust.verify-llvm-ir', '--set', 'rust.codegen-backends=llvm,cranelift,gcc', '--set', 'llvm.static-libstdcpp', '--set', 'gcc.download-ci-gcc=true', '--enable-new-symbol-mangling']
configure: build.build          := x86_64-unknown-linux-gnu
configure: target.x86_64-unknown-linux-gnu.llvm-config := /usr/lib/llvm-19/bin/llvm-config
configure: llvm.link-shared     := True
configure: rust.randomize-layout := True
configure: rust.thin-lto-import-instr-limit := 10
---
failures:

---- [ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature3 stdout ----

error in revision `by_feature3`: /checkout/tests/ui/target-feature/retpoline-target-feature-flag.rs:?: unexpected WARN: '?:?: ?:?: target feature `retpoline-indirect-calls` cannot be enabled with `-Ctarget-feature`: use `retpoline` target modifier flag instead'

error in revision `by_feature3`: 1 unexpected errors found, 0 expected errors not found
status: exit status: 0
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/target-feature/retpoline-target-feature-flag.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--cfg" "by_feature3" "--check-cfg" "cfg(test,FALSE,by_flag,by_feature1,by_feature2,by_feature3)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/target-feature/retpoline-target-feature-flag.by_feature3" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target=x86_64-unknown-linux-gnu" "--crate-type=lib" "-Ctarget-feature=+retpoline-indirect-calls"

--- unexpected errors (from JSON output) ---
WARNline   ?: ?:?: ?:?: target feature `retpoline-indirect-calls` cannot be enabled with `-Ctarget-feature`: use `retpoline` target modifier flag instead
---

thread '[ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature3' panicked at src/tools/compiletest/src/runtest.rs:790:13:
errors differ from expected

---- [ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature2 stdout ----

error in revision `by_feature2`: /checkout/tests/ui/target-feature/retpoline-target-feature-flag.rs:?: unexpected WARN: '?:?: ?:?: target feature `retpoline-indirect-branches` cannot be enabled with `-Ctarget-feature`: use `retpoline` target modifier flag instead'

error in revision `by_feature2`: 1 unexpected errors found, 0 expected errors not found
status: exit status: 0
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/target-feature/retpoline-target-feature-flag.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--cfg" "by_feature2" "--check-cfg" "cfg(test,FALSE,by_flag,by_feature1,by_feature2,by_feature3)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/target-feature/retpoline-target-feature-flag.by_feature2" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target=x86_64-unknown-linux-gnu" "--crate-type=lib" "-Ctarget-feature=+retpoline-indirect-branches"

--- unexpected errors (from JSON output) ---
WARNline   ?: ?:?: ?:?: target feature `retpoline-indirect-branches` cannot be enabled with `-Ctarget-feature`: use `retpoline` target modifier flag instead
---

thread '[ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature2' panicked at src/tools/compiletest/src/runtest.rs:790:13:
errors differ from expected

---- [ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature1 stdout ----

error in revision `by_feature1`: /checkout/tests/ui/target-feature/retpoline-target-feature-flag.rs:?: unexpected WARN: '?:?: ?:?: target feature `retpoline-external-thunk` cannot be enabled with `-Ctarget-feature`: use `retpoline-external-thunk` target modifier flag instead'

error in revision `by_feature1`: 1 unexpected errors found, 0 expected errors not found
status: exit status: 0
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/target-feature/retpoline-target-feature-flag.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--cfg" "by_feature1" "--check-cfg" "cfg(test,FALSE,by_flag,by_feature1,by_feature2,by_feature3)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/target-feature/retpoline-target-feature-flag.by_feature1" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target=x86_64-unknown-linux-gnu" "--crate-type=lib" "-Ctarget-feature=+retpoline-external-thunk"

--- unexpected errors (from JSON output) ---
WARNline   ?: ?:?: ?:?: target feature `retpoline-external-thunk` cannot be enabled with `-Ctarget-feature`: use `retpoline-external-thunk` target modifier flag instead
---

thread '[ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature1' panicked at src/tools/compiletest/src/runtest.rs:790:13:
errors differ from expected


failures:
    [ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature3
    [ui] tests/ui/target-feature/retpoline-target-feature-flag.rs#by_feature2