Sema: detect and skip over elided instructions

stage2: fix test cases to add `pub` on exported _start fn

stage2: fix source location of Decl compile errors

stage2: build and provide libunwind when compiling for native libc

stage2: fix handling of "prev successful ZIR"

std: fix redundant comptime keywords

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen

stage2: more Decl lifetime fixes

stage2: improve Decl lifetime management

Sema: implement duplicate enum tag compile error

stage2: lookupIdentifier can return error.AnalysisFailed

stage2: better handling of file-level compile errors across updates

stage2: update tests now that structs have fully qualified names

C backend: fix emitting '$' in identifier names

AstGen: support emitting multiple compile errors

stage2: add `owns_tv` flag to `Module.Decl`

stage2: struct, union, enum, opaque, error sets get better names

stage2: type declarations ZIR encode AnonNameStrategy

stage1: ignore enum ContainerLayout for comptime memory purposes

stage2 test harness: report multiple failures

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen

stage2: fully qualified names and better anonymous names

Sema: fix `@setEvalBranchQuota` incorrectly requiring a function body

AstGen: fix incorrect logic for adding implicit return instruction

Type: fix abiAlignment calculation for unions

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen

stage2: fix struct inits not getting fields resolved

ZIR: implement iteration over switch instructions

std: start code on linux when -lc also expands stack size

std: start code increases stack size as appropriate on linux

stage2: fix stack overflow in `@setEvalBranchQuota` test case

stage2: implement global variables

stage2: no '$' in anonymous decl names

stage2: implement extern functions

Sema: support enough to check main calling convention via `@typeInfo`

Sema: implement `@typeInfo` for functions

stage2: CBE tests `pub export` instead of `export` main

stage2: fix compile errors in test harness

CLI: add an update-and-run cmd and make enter re-run last cmd

stage2: wire up outdated/deleted decl detection

CLI: add 'run' command to the repl

std.ArrayHashMap: ensureUnusedCapacity and ensureTotalCapacity

stage2: fix contents hash computation

stage2: mapping old to new ZIR recursively

std.ArrayList: add clearRetainingCapacity and clearAndFree

stage2: add `zig changelist` debug command

std: fix compile errors found by stage2

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen

Sema: restore the extern lib name functionality

stage2: test coverage for inline asm return type not type

Sema: implement error sets

stage2: fix "other symbol here" error note

stage2: fix structs and enums setting wrong owner_decl

build.zig: add -Dmem-leak-frames option

Sema: implement ExportOptions support in `@export`

ZIR: typeof uses the un_node field not un_tok

Sema: implement struct_decl instruction

ZIR: implement debug text printing for struct_init and friends

stage2: hook up semantic analysis of struct fields

stage2: make struct field analysis lazy

AstGen: fix outdated doc comment

AstGen: decouple from Module/Compilation

stage2: fix error reporting not loading AST

stage2: test decls encode that they are tests in ZIR

Sema: fix struct decl decoding ZIR incorrectly

stage2: dbg_stmt ZIR instructions have line/col

std.GeneralPurposeAllocator: print leaked memory addresses

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen

stage2: implement function body analysis

stage2: introduce new ZIR instruction: arg

Sema: implement function declarations

start.zig: unconditionally import the root source file

stage2: un-tangle memory management of Decl and Namespace

stage2: fix File incorrectly freeing its Namespace

stage2: properly free Decl name

std: fix compile errors found by stage2 AstGen

AstGen: represent global variables directly

AstGen: implement extern variables

AstGen: implement function prototypes with alignment exprs

AstGen: fix comptime compile error source location

Sema: rename TZIR to AIR

Sema: skip analysis of empty enum blocks

AstGen: implement anytype struct fields

AstGen: implement comptime struct fields

std.enums: remove stuff for enums with field aliases

move behavior tests from test/stage1/ to test/

update behavior tests with respect to new builtin pkg

tests: prepare behavior tests for stage2

stage2: fix scanDecls not advancing the field bits

std: remove redundant comptime keyword

stage2: implement semantic analysis for functions and global vars

stage2: prepare for mainining Decl references to ZIR indexes

stage2: semaDecl properly analyzes the decl block

Sema: do not analyze test decls when not in test mode

stage2: implement #8364

std: remove redundant `comptime const`

AstGen: hook up hex float parsing to float literals

AstGen: function prototypes can have alignment

Merge remote-tracking branch 'origin/master' into stage2-whole-file-astgen