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[ELF] Change -z unknown from error to warning

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There is a trend of having more optional options (usually security
hardening related) like -z cet-report=, -z bti-report=, -z force-bti.
If ld.lld 14.0.0 uses a warning, in 15/16/17/... timeframe when people
add new options to software, they can worry less about linker errors on ld.lld 14.0.0.

In some cases `-z foo` does essential work where a silent ignore can be
problematic, but the user has received a warning. From my observation, the
doing-essential-work `-z foo` is much fewer than the converse. In addition,
the user who cares can use `--fatal-warnings` (Note: GNU ld doesn't upgrade warnings to errors).
It is unclear whether we need something like `clang -Wunknown-warning-option`.

If we ever run into unfortunate transition like `-z start-stop-gc`, the
affected software (e.g. ldc is a compiler which passes linker options to the underlying ld)
can blindly add the `-z` option, without worrying it may cause a linker error to LLD 14.0.0.

Reviewed By: jrtc27, peter.smith

Differential Revision: https://reviews.llvm.org/D114748
This commit is contained in:
Fangrui Song
2021-11-30 11:06:28 -08:00
parent 299cec3c51
commit 8c3641d03e
2 changed files with 13 additions and 9 deletions
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10
lld/ELF/Driver.cpp
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@@ -460,19 +460,21 @@ static bool isKnownZFlag(StringRef s) {
s.startswith("start-stop-visibility=");
}
// Report an error for an unknown -z option.
// Report a warning for an unknown -z option.
static void checkZOptions(opt::InputArgList &args) {
for (auto *arg : args.filtered(OPT_z))
if (!isKnownZFlag(arg->getValue()))
error("unknown -z value: " + StringRef(arg->getValue()));
warn("unknown -z value: " + StringRef(arg->getValue()));
}
void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
ELFOptTable parser;
opt::InputArgList args = parser.parse(argsArr.slice(1));
// Interpret this flag early because error() depends on them.
// Interpret the flags early because error()/warn() depend on them.
errorHandler().errorLimit = args::getInteger(args, OPT_error_limit, 20);
errorHandler().fatalWarnings =
args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
checkZOptions(args);
// Handle -help
@@ -971,8 +973,6 @@ static void parseClangOption(StringRef opt, const Twine &msg) {
// Initializes Config members by the command line options.
static void readConfigs(opt::InputArgList &args) {
errorHandler().verbose = args.hasArg(OPT_verbose);
errorHandler().fatalWarnings =
args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
errorHandler().vsDiagnostics =
args.hasArg(OPT_visual_studio_diagnostics_format, false);

12
lld/test/ELF/driver.test
View File

@@ -58,12 +58,16 @@
# RUN: not ld.lld %t -output=/no/such/file 2>&1 | FileCheck -check-prefix=ERR9 %s
# ERR9: cannot open output file utput=/no/such/file
# RUN: not ld.lld %t -z foo 2>&1 | FileCheck -check-prefix=ERR10 %s
# RUN: not ld.lld %t -z foo --version 2>&1 | FileCheck -check-prefix=ERR10 %s
# ERR10: unknown -z value: foo
# RUN: ld.lld %t -z foo 2>&1 | FileCheck -check-prefix=ERR10 %s
# RUN: ld.lld %t -z foo --version 2>&1 | FileCheck -check-prefix=ERR10 %s
# ERR10: warning: unknown -z value: foo
## Check we report "unknown -z value" error even with -v.
# RUN: not ld.lld %t -z foo -v 2>&1 | FileCheck -check-prefix=ERR10 %s
# RUN: ld.lld %t -z foo -v 2>&1 | FileCheck -check-prefix=ERR10 %s
## Note: in GNU ld, --fatal-warning still leads to a warning.
# RUN: not ld.lld %t -z foo --fatal-warnings 2>&1 | FileCheck --check-prefix=ERR10-FATAL %s
# ERR10-FATAL: error: unknown -z value: foo
# RUN: not ld.lld %t -z max-page-size 2>&1 | FileCheck -check-prefix=ERR11 %s
# ERR11: unknown -z value: max-page-size