Invalid instruction error even though no invalid instructions emitted

[negge]

I am getting error E1156: Assembler error: 'Invalid instruction with current CPU setting' even though no invalid instructions are emitted when compiling. For example:

int times3(int a);
#pragma aux times3 parm [ax] value [ax] = \
  "imul ax, 3"

void main() {
}

when compiled with wcc -0 test.c gives the following error:

$ wcc -0 test.c
Open Watcom C x86 16-bit Optimizing Compiler
Version 2.0 beta Jun  1 2024 01:58:31 (32-bit)
Copyright (c) 2002-2024 The Open Watcom Contributors. All Rights Reserved.
Portions Copyright (c) 1984-2002 Sybase, Inc. All Rights Reserved.
Source code is available under the Sybase Open Watcom Public License.
See https://github.com/open-watcom/open-watcom-v2#readme for details.
test.c(3): Error! E1156: Assembler error: 'Invalid instruction with current CPU setting'
test.c: 7 lines, 0 warnings, 1 errors

This should be a warning at most, and preferably not even that, since times3() is never called.

[jmalak]

IMUL reg,imm is invalid on 8086.
#pragma aux times3 is template, not instantiated in code then it isn't reason to suppress error.