Nested context type mismatch -> ICE when building vibe.d

[dnadlinger]

Another nested context problem when building vibe.d (from the 0.7.21-rc.2 Git tag):

~/vibe-d-0.7.21-rc.2/source $ ldc2 vibe/db/mongo/connection.d vibe/http/router.d
ldc2: llvm/lib/IR/Instructions.cpp:2377: static llvm::CastInst* llvm::CastInst::Create(llvm::Instruction::CastOps, llvm::Value*, llvm::Type*, const llvm::Twine&, llvm::Instruction*): Assertion `castIsValid(op, S, Ty) && "Invalid cast!"' failed.
0  ldc2            0x0000000001b8d361 llvm::sys::PrintStackTrace(_IO_FILE*) + 38
1  ldc2            0x0000000001b8d5d9
2  ldc2            0x0000000001b8cf69
3  libpthread.so.0 0x00007ff14ecf0200
4  libc.so.6       0x00007ff14d8bf967 gsignal + 55
5  libc.so.6       0x00007ff14d8c0d3a abort + 362
6  libc.so.6       0x00007ff14d8b88ad
7  libc.so.6       0x00007ff14d8b8962
8  ldc2            0x0000000001a413a5 llvm::CastInst::Create(llvm::Instruction::CastOps, llvm::Value*, llvm::Type*, llvm::Twine const&, llvm::Instruction*) + 87
9  ldc2            0x0000000000c4a08d
10 ldc2            0x0000000000c494f4
11 ldc2            0x0000000000c475c4 DtoBitCast(llvm::Value*, llvm::Type*, char const*) + 163
12 ldc2            0x0000000000d52edf DtoCallFunction(Loc&, Type*, DValue*, Array<Expression*>*, llvm::Value*) + 1970
13 ldc2            0x0000000000d42bbe
14 ldc2            0x0000000000b132ec
15 ldc2            0x0000000000d4d62a toElem(Expression*) + 69
16 ldc2            0x0000000000d4db94 toElemDtor(Expression*) + 710

Dustmite is running on this right now.

[dnadlinger]

Fairly minimal testcase in terms of non-Phobos code:

module router;
struct MatchTree
{
        struct TerminalTag {}
        TerminalTag[] m_terminalTags;

        void print()
        {
                import std.algorithm;
                import std.array;
                m_terminalTags.map!(t => "").array;
        }
}

module bson;
import std.algorithm;

Build as

ldc2 bson.d router.d

The other way round, the issues does not appear.

[dnadlinger]

Another round of Dustmite and some more manual simplification later:

module algorithm;
import range;

template map(fun...) {
    auto map(Range)(Range) {
        return MapResult!(fun, Range)();
    }
}

struct MapResult(alias fun, R) {
    R _input;
    MapResult opSlice() {
        return MapResult();
    }
}

module range;
void array(Range)(Range r) {}

module router;
import algorithm;
import range;

struct MatchTree {
    struct TerminalTag {}
    TerminalTag[] m_terminalTags;

    void print() {
        m_terminalTags.map!(t => "").array;
    }
}

ldc2 -c algorithm.d router.d