Bug 19937 – object._d_assert_fail linker error if compiling with -checkaction=context

import std.stdio; import std.json; void main() { auto j = parseJSON(`[ "abc", "def", "ghi" ]`); } $ dmd -checkaction=context checkaction.d /usr/bin/ld: c.o: in function `_D3std3uni__T4TrieTSQsQq__T9BitPackedTbVmi1ZQrTwVmi1114112TSQCgQCf__T9sliceBitsVmi13Vmi21ZQvTSQDoQDn__TQBiVmi8Vmi13ZQBvTSQEpQEo__TQCjVmi0Vmi8ZQCvZQFd__T7opIndexZQjMxFNaNbNiNewZb': checkaction.d:(.text._D3std3uni__T4TrieTSQsQq__T9BitPackedTbVmi1ZQrTwVmi1114112TSQCgQCf__T9sliceBitsVmi13Vmi21ZQvTSQDoQDn__TQBiVmi8Vmi13ZQBvTSQEpQEo__TQCjVmi0Vmi8ZQCvZQFd__T7opIndexZQjMxFNaNbNiNewZb[_D3std3uni__T4TrieTSQsQq__T9BitPackedTbVmi1ZQrTwVmi1114112TSQCgQCf__T9sliceBitsVmi13Vmi21ZQvTSQDoQDn__TQBiVmi8Vmi13ZQBvTSQEpQEo__TQCjVmi0Vmi8ZQCvZQFd__T7opIndexZQjMxFNaNbNiNewZb]+0x52): undefined reference to `_D6object__T14_d_assert_failVAyaa1_3cTmTmZQBeFNaNbNiNfmmZQBc' collect2: error: ld returned 1 exit status Error: linker exited with status 1 demangles to pure nothrow @nogc @safe immutable(char)[] object._d_assert_fail!("<", ulong, ulong)._d_assert_fail(ulong, ulong)

Apologies, I should mention Manjaro/Arch x86_64, dmd v2.086.0 from official repositories.

Demangled: --- checkaction.o:checkaction.d:function const pure nothrow @nogc @trusted bool std.uni.Trie!(std.uni.BitPacked!(bool, 1uL).BitPacked, dchar, 1114112uL, std.uni.sliceBits!(13uL, 21uL).sliceBits, std.uni.sliceBits!(8uL, 13uL).sliceBits, std.uni.sliceBits!(0uL, 8uL).sliceBits).Trie.opIndex!().opIndex(dchar): error: undefined reference to 'pure nothrow @nogc @safe immutable(char)[] object._d_assert_fail!("<", ulong, ulong)._d_assert_fail(ulong, ulong)' --- Code generated from DMD looks like this: ``` inout pure nothrow @nogc @system BitPacked!(bool, 1LU) opIndex(ulong idx) in { assert(idx < this.limit, _d_assert_fail(idx, this.limit)); } do { { { assert(idx < this.limit, _d_assert_fail(idx, this.limit)); } } return this.ptr.opIndex(this.ofs + idx); } ``` ... ``` _d_assert_fail!("<", ulong, ulong) { pure nothrow @nogc @safe string _d_assert_fail(ulong a, ulong b) { import core.internal.dassert : invertCompToken, miniFormatFakeAttributes, pureAlloc; string valA = miniFormatFakeAttributes(a); string valB = miniFormatFakeAttributes(b); enum string token = ">="; const const(ulong) totalLen = valA.length + 2LU + valB.length + 2LU; char[] buffer = cast(char[])pureAlloc(totalLen)[0..totalLen]; ulong n = valA.length; buffer[0..n] = cast(const(char[]))valA; buffer[n++] = ' '; buffer[n..n + 2LU] = ">="; n += 2LU; buffer[n++] = ' '; buffer[n..n + valB.length] = cast(const(char[]))valB; return delegate () => cast(string)buffer(); } } ``` but it doesn't appear in the object file: ``` $ nm bar.o | grep assert_fail | ddemangle 0000000000000000 W pure nothrow @nogc @trusted immutable(char)[] object._d_assert_fail!("<", uint, uint)._d_assert_fail(uint, uint).__lambda3() 0000000000000000 W pure nothrow @nogc @safe immutable(char)[] object._d_assert_fail!("<", uint, uint)._d_assert_fail(uint, uint) U pure nothrow @nogc @safe immutable(char)[] object._d_assert_fail!("<", ulong, ulong)._d_assert_fail(ulong, ulong) 0000000000000000 W pure nothrow @nogc @trusted immutable(char)[] object._d_assert_fail!(">=", uint, uint)._d_assert_fail(uint, uint).__lambda3() 0000000000000000 W pure nothrow @nogc @safe immutable(char)[] object._d_assert_fail!(">=", uint, uint)._d_assert_fail(uint, uint) ``` DMD probably thinks that this assertion was already instantiated in Phobos (and thus should be part of the object file), but it is not as Phobos was build without -checkaction=context.

BTW a workaround is to do force the instantiation e.g. with the following hack: ``` cat << EOF > workaround.d void test(ulong x, ulong y){ assert(x < y); } EOF ``` ``` dmd -checkaction=context -c workaround.d dmd -checkaction=context workaround.o checkaction.d ```

I'm seeing this with anything that involves Vibe.d as well, with DMD v2.090.1.

@Seb: Thanks for the pointer. Unfortunately in the Vibe.d case it is nastier, because the symbol takes a `ref` and a non-ref. Turns out `assert(x > y)` and `assert(x > 0)` will generate different symbol (the former's second argument is `ref` while the later is not, being a rvalue).

Assuming Seb's assessment of phobos being compiled without `-checkaction=context` is the root cause, here is another test case: ``` import std; void main() { wchar[] c; c.toUTF8; } ``` Compiling this with `-checkaction=context` produces ``` Error 42: Symbol Undefined __D4core8internal7dassert__T24miniFormatFakeAttributesTkZQBdFNaNbNiNfKxkZAya ``` The link error vanishes if the argument `-debug` or `-release` is added, or if the import is changed into `import std.utf;`. This happens for DMD64 D Compiler v2.091.0-dirty on Windows, couldn't reproduce this on run.dlang.io. Bastiaan.

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