treewide: fix a bunch of lints

Fixes:
- Identifiers starting with _ are prohibited
- Some driveby header dependency cleaning which wound up with doing some
  extra fixups.
- Fucking C style casts, man. C++ made these 1000% worse by letting you
  also do memory corruption with them with references.
  - Remove casts to Expr * where ExprBlackHole is an incomplete type by
    introducing an explicitly-cast eBlackHoleAddr as Expr *.
  - An incredibly illegal cast of the text bytes of the StorePath hash
    into a size_t directly. You can't DO THAT.

    Replaced with actually parsing the hash so we get 100% of the bits
    being entropy, then memcpying the start of the hash. If this shows
    up in a profile we should just make the hash parser faster with a
    lookup table or something sensible like that.
  - This horrendous bit of UB which I thankfully slapped a deprecation
    warning on, built, and it didn't trigger anywhere so it was dead
    code and I just deleted it. But holy crap you *cannot* do that.

    inline void mkString(const Symbol & s)
    {
        mkString(((const std::string &) s).c_str());
    }
- Some wrong lints. Lots of wrong macro lints, one wrong
  suspicious-sizeof lint triggered by the template being instantiated
  with only pointers, but the calculation being correct for both
  pointers and not-pointers.
- Exceptions in destructors strike again. I tried to catch the
  exceptions that might actually happen rather than all the exceptions
  imaginable. We can let the runtime hard-kill it on other exceptions
  imo.

Change-Id: I71761620846cba64d66ee7ca231b20c061e69710

src/libutil/error.hh

@@ -16,16 +16,12 @@
  */
 
 #include "suggestions.hh"
-#include "ref.hh"
-#include "types.hh"
 #include "fmt.hh"
 
 #include <cstring>
 #include <list>
 #include <memory>
-#include <map>
 #include <optional>
-#include <compare>
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -173,6 +169,7 @@ public:
 };
 
 #define MakeError(newClass, superClass) \
+    /* NOLINTNEXTLINE(bugprone-macro-parentheses) */    \
     class newClass : public superClass                  \
     {                                                   \
     public:                                             \

src/libutil/finally.hh

@@ -22,6 +22,7 @@ public:
     Finally(Finally &&other) : fun(std::move(other.fun)) {
         other.movedFrom = true;
     }
+    // NOLINTNEXTLINE(bugprone-exception-escape): the noexcept is declared properly here, the analysis seems broken
     ~Finally() noexcept(noexcept(fun()))
     {
         try {

src/libutil/hash.cc

@@ -7,6 +7,7 @@
 #include "args.hh"
 #include "hash.hh"
 #include "archive.hh"
+#include "charptr-cast.hh"
 #include "logging.hh"
 #include "split.hh"
 
@@ -129,7 +130,7 @@ std::string Hash::to_string(Base base, bool includeType) const
         break;
     case Base::Base64:
     case Base::SRI:
-        s += base64Encode(std::string_view(reinterpret_cast<const char *>(hash), hashSize));
+        s += base64Encode(std::string_view(charptr_cast<const char *>(hash), hashSize));
         break;
     }
     return s;

src/libutil/serialise.cc

@@ -1,4 +1,5 @@
 #include "serialise.hh"
+#include "charptr-cast.hh"
 #include "signals.hh"
 
 #include <cstring>

src/libutil/serialise.hh

@@ -4,6 +4,7 @@
 #include <concepts>
 #include <memory>
 
+#include "charptr-cast.hh"
 #include "generator.hh"
 #include "strings.hh"
 #include "types.hh"
@@ -385,7 +386,7 @@ struct SerializingTransform
         buf[5] = (n >> 40) & 0xff;
         buf[6] = (n >> 48) & 0xff;
         buf[7] = (unsigned char) (n >> 56) & 0xff;
-        return {reinterpret_cast<const char *>(buf.begin()), 8};
+        return {charptr_cast<const char *>(buf.begin()), 8};
     }
 
     static Bytes padding(size_t unpadded)
@@ -417,6 +418,9 @@ struct SerializingTransform
 
 void writePadding(size_t len, Sink & sink);
 
+// NOLINTBEGIN(cppcoreguidelines-avoid-capturing-lambda-coroutines):
+// These coroutines do their entire job before the semicolon and are not
+// retained, so they live long enough.
 inline Sink & operator<<(Sink & sink, uint64_t u)
 {
     return sink << [&]() -> WireFormatGenerator { co_yield u; }();
@@ -441,6 +445,7 @@ inline Sink & operator<<(Sink & sink, const Error & ex)
 {
     return sink << [&]() -> WireFormatGenerator { co_yield ex; }();
 }
+// NOLINTEND(cppcoreguidelines-avoid-capturing-lambda-coroutines)
 
 MakeError(SerialisationError, Error);
 
@@ -448,7 +453,7 @@ template<typename T>
 T readNum(Source & source)
 {
     unsigned char buf[8];
-    source((char *) buf, sizeof(buf));
+    source(charptr_cast<char *>(buf), sizeof(buf));
 
     auto n = readLittleEndian<uint64_t>(buf);
 
@@ -540,13 +545,17 @@ struct FramedSource : Source
 
     ~FramedSource()
     {
-        if (!eof) {
-            while (true) {
-                auto n = readInt(from);
-                if (!n) break;
-                std::vector<char> data(n);
-                from(data.data(), n);
+        try {
+            if (!eof) {
+                while (true) {
+                    auto n = readInt(from);
+                    if (!n) break;
+                    std::vector<char> data(n);
+                    from(data.data(), n);
+                }
             }
+        } catch (...) {
+            ignoreException();
         }
     }
 

src/libutil/signals.cc

@@ -3,6 +3,7 @@
 #include "sync.hh"
 #include "terminal.hh"
 
+#include <map>
 #include <thread>
 
 namespace nix {

src/libutil/thread-pool.hh

@@ -4,6 +4,7 @@
 #include "error.hh"
 #include "sync.hh"
 
+#include <map>
 #include <queue>
 #include <functional>
 #include <thread>

src/libutil/url.hh

@@ -2,6 +2,7 @@
 ///@file
 
 #include "error.hh"
+#include <map>
 
 namespace nix {
 

src/libutil/variant-wrapper.hh

@@ -8,6 +8,7 @@
  * Force the default versions of all constructors (copy, move, copy
  * assignment).
  */
+// NOLINTBEGIN(bugprone-macro-parentheses)
 #define FORCE_DEFAULT_CONSTRUCTORS(CLASS_NAME) \
     CLASS_NAME(const CLASS_NAME &) = default; \
     CLASS_NAME(CLASS_NAME &) = default; \
@@ -15,6 +16,7 @@
     \
     CLASS_NAME & operator =(const CLASS_NAME &) = default; \
     CLASS_NAME & operator =(CLASS_NAME &) = default;
+// NOLINTEND(bugprone-macro-parentheses)
 
 /**
  * Make a wrapper constructor. All args are forwarded to the