-mllvm -wasm-enable-sjlj, in every wasm compile because setjmp.h does
not compile without it, turns setjmp and longjmp into calls to
__wasm_setjmp, __wasm_setjmp_test and __wasm_longjmp and a throw of
the __c_longjmp tag, all of which live in wasi-libc's libsetjmp. The
driver does not link it, so a program that used setjmp, or a C library
that handles its errors that way, failed to link with undefined
__wasm_setjmp until the project put -lsetjmp in its linkFlags.
Build() adds it to every wasm link, next to -lunwind. A static archive
contributes only the members something references, so a program
without setjmp gets nothing from it, and every sysroot that passes the
exception check ships it. WasmExceptions drops its own -lsetjmp, and
its C fixture now fails to link without this.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
WasmBuildRefusals checks that -flto in compileFlags and in linkFlags,
-fno-exceptions and a shared library are each refused with their
cause, and that none of them leaves bin/ or build/ behind. With the
check disabled, each of them failed on a missing std.cppm instead,
after the build directories had been made.
WasiSysrootWithoutExceptions also takes its sysroot through missing
and without the target's directory, each with a message of its own,
checks that a refused build leaves nothing behind, and that a static
library passes without libunwind.
WasmExceptions catches an exception thrown inside libc++.a (stoi).
vector::at throws from a header compiled into the fixture, so the
fixture also passed against the libc++ built without exceptions. Its C
source uses setjmp, which the old C flags did not compile. An
exception that escapes main has to end the run as wasmtime's uncaught
exception, where any nonzero exit used to pass, a trap or a timeout
included.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
WasmExceptions builds a fixture for wasm32-wasip1 and runs it under
wasmtime. It throws through four frames whose destructors have to run,
catches the exception, catches one that vector::at throws, and with an
argument lets one escape main, which has to fail the run. With the
previous flags the fixture does not compile ("cannot use 'throw' with
exceptions disabled"), and each part of turning exceptions on fails it
in its own way, from a BMI built without them to the legacy encoding
wasmtime refuses.
WasiSysrootWithoutExceptions takes a scratch sysroot through three
states, no libunwind, libunwind under eh/ and libunwind in the
triple's own directory, and checks that only the first stops the
build, with the message naming the library it looked for. It needs no
working wasm toolchain, so it also runs where the others skip.
WasmHelloRuns and WasmExceptions treat a sysroot without the
exception-enabled libraries as missing and skip. The manifest tests
expect the exception-handling probe on every entry.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
