Enable -Wswitch-enum GCC and Clang flag #2087
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`default` keyword silences "warning: enumeration value ‘FOO’ not handled in switch", making some bugs hard to spot. This caused issue atomvm#2086: `term_compare()` wasn't handling funs due to an unnoticed missing case. However `default` is still useful for telling compiler than any other case is unreachable, but we don't want to silence warnings. So the right strategy is using `-Wswitch-enum`, while doing fall through to the default, for each enum value that we explicitly don't want to handle. Signed-off-by: Davide Bettio <davide@uninstall.it>
Those missing cases were legit, still not obvious and they were causing a warning now. Signed-off-by: Davide Bettio <davide@uninstall.it>
mat-hek
reviewed
Feb 6, 2026
| // `type_t == type_other`, | ||
| // but we do `t == other` as the first thing, making this case unreachable. | ||
| case TERM_TYPE_INDEX_INVALID: | ||
| default: |
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default: UNREACHABLE(); tells the compiler that any other value is undefined behavior, so it can perform additional optimizations. Otherwise it stills emit code for handling values outside the cases we defined.
Variables having an enum type are glorified integers, so the compiler by default doesn't infer that only allowed values are the enum values.
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This will prevent bugs such as #2086.
These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).
SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later