Issue #514 : Fix compileRegAssignment cardinality #528
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Use `nvars` as the assignment numbers rather than `lennames`. This makes no difference in `compileLocalAssignStmt` as the numbers are equal, but in `compileGenericForStmt` the names are the iteration variables while `nvars` refers to the local generator, state, and control. The iteration variables feel a bit out of place here. The whole body of `compileRegAssignment` seem inconsistent, using `names` only for its length, and mixing `lennames` and `nvars` in surprising ways. Moreover the function name `compileRegAssignment` suggests assigning to registers rather than names, so I dropped `lennames` entirely to use only `nvars`.
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Fixes #514
Changes proposed in this pull request:
compileRegAssignment, usenvarsas the assignment cardinality rather thanlennames.namesargumentI don't really know what I'm doing, I just tried to infer what things were supposed to be doing based on their names. I started with the test case filed in #514 and compared with the behavior of official Lua 5.1. It turned out that
luachas extraLOADNILwhich reset the registers that weren't correctly reset by gopher-lua, so I poked aroundcompileGenericForStmtand it took me a while to understand why the iteration variable names were fed tocompileRegAssignmentwhen its place in the code and the other arguments suggested it should be about initializing internal generator/state/control triplet rather than iteration variables.I checked that after this change, the opcodes generated by gopher-lua are similar to those from luac, and the whole test suite passes.