[Clang] Confusing diagnostic when using `-fsanitize=function -mexecute-only` flags together on ARM targets

[Il-Capitano]

When passing -fsanitize=function -mexecute-only to Clang on an ARM target, it prints the following error:

error: invalid argument '-fsanitize=function' not allowed with 'arm-unknown-linux-gnueabi'

The error happens because -fsanitize=function is incompatible with execute-only memory, but prints the target triple as the reason. I would expect the error message to be the following in this case:

error: invalid argument '-fsanitize=function' not allowed with '-mexecute-only'

The diagnostic is created here:

llvm-project/clang/lib/Driver/SanitizerArgs.cpp

Lines 416 to 423 in 69d66fa

	if (isExecuteOnlyTarget(Triple, Args)) {
	if (SanitizerMask KindsToDiagnose =
	Add & NotAllowedWithExecuteOnly & ~DiagnosedKinds) {
	if (DiagnoseErrors) {
	std::string Desc = describeSanitizeArg(Arg, KindsToDiagnose);
	D.Diag(diag::err_drv_argument_not_allowed_with)
	<< Desc << Triple.str();
	}

I think a good solution would be to print -mexecute-only (or -mpure-code) as the reason for the incompatibility if it was passed to the compiler driver, and print the target triple otherwise.

[llvmbot]

@llvm/issue-subscribers-clang-driver

Author: Csanád Hajdú (Il-Capitano)

When passing `fsanitize=function -mexecute-only` to Clang on an ARM target, it prints the following error: ``` error: invalid argument '-fsanitize=function' not allowed with 'arm-unknown-linux-gnueabi' ``` The error happens because `-fsanitize=function` is incompatible with execute-only memory, but prints the target triple as the reason. I would expect the error message to be the following in this case: ``` error: invalid argument '-fsanitize=function' not allowed with '-mexecute-only' ```

The diagnostic is created here:

llvm-project/clang/lib/Driver/SanitizerArgs.cpp

Lines 416 to 423 in 69d66fa

	if (isExecuteOnlyTarget(Triple, Args)) {
	if (SanitizerMask KindsToDiagnose =
	Add & NotAllowedWithExecuteOnly & ~DiagnosedKinds) {
	if (DiagnoseErrors) {
	std::string Desc = describeSanitizeArg(Arg, KindsToDiagnose);
	D.Diag(diag::err_drv_argument_not_allowed_with)
	<< Desc << Triple.str();
	}

I think a good solution would be to print -mexecute-only (or -mpure-code) as the reason for the incompatibility if it was passed to the compiler driver, and print the target triple otherwise.