Merge bitcoin/bitcoin#23156: refactor: Remove unused ParsePrechecks and ParseDouble

fa9d72a7947d2cff541794e21e0040c3c1d43b32 Remove unused ParseDouble and ParsePrechecks (MarcoFalke)
fa3cd2853530c86c261ac7266ffe4f1726fe9ce6 refactor: Remove unused ParsePrechecks from ParseIntegral (MarcoFalke)

Pull request description:

  All of the `ParsePrechecks` are already done by `ToIntegral`, so remove them from `ParseIntegral`.

  Also:
  * Remove redundant `{}`. See https://github.com/bitcoin/bitcoin/pull/20457#discussion_r720116866
  * Add missing failing c-string test case
  * Add missing failing test cases for non-int32_t integral types

ACKs for top commit:
  laanwj:
    Code review ACK fa9d72a7947d2cff541794e21e0040c3c1d43b32, good find on ParseDouble not being used at all, and testing for behavior of embedded NULL characters is always a good thing.
  practicalswift:
    cr ACK fa9d72a7947d2cff541794e21e0040c3c1d43b32

Tree-SHA512: 3d654dcaebbf312dd57e54241f9aa6d35b1d1d213c37e4c6b8b9a69bcbe8267a397474a8b86b57740fbdd8e3d03b4cdb6a189a9eb8e05cd38035dab195410aa7

2 files changed, 4 insertions, 39 deletions

diff --git a/src/util/strencodings.cpp b/src/util/strencodings.cpp
index 88fec6740a..15bd07b374 100644
--- a/src/util/strencodings.cpp
+++ b/src/util/strencodings.cpp
@@ -281,16 +281,11 @@ std::string DecodeBase32(const std::string& str, bool* pf_invalid)
     return std::string((const char*)vchRet.data(), vchRet.size());
 }
 
-[[nodiscard]] static bool ParsePrechecks(const std::string&);
-
 namespace {
 template <typename T>
 bool ParseIntegral(const std::string& str, T* out)
 {
     static_assert(std::is_integral<T>::value);
-    if (!ParsePrechecks(str)) {
-        return false;
-    }
     // Replicate the exact behavior of strtol/strtoll/strtoul/strtoull when
     // handling leading +/- for backwards compatibility.
     if (str.length() >= 2 && str[0] == '+' && str[1] == '-') {
@@ -307,17 +302,6 @@ bool ParseIntegral(const std::string& str, T* out)
 }
 }; // namespace
 
-[[nodiscard]] static bool ParsePrechecks(const std::string& str)
-{
-    if (str.empty()) // No empty string allowed
-        return false;
-    if (str.size() >= 1 && (IsSpace(str[0]) || IsSpace(str[str.size()-1]))) // No padding allowed
-        return false;
-    if (!ValidAsCString(str)) // No embedded NUL characters allowed
-        return false;
-    return true;
-}
-
 bool ParseInt32(const std::string& str, int32_t* out)
 {
     return ParseIntegral<int32_t>(str, out);
@@ -348,20 +332,6 @@ bool ParseUInt64(const std::string& str, uint64_t* out)
     return ParseIntegral<uint64_t>(str, out);
 }
 
-bool ParseDouble(const std::string& str, double *out)
-{
-    if (!ParsePrechecks(str))
-        return false;
-    if (str.size() >= 2 && str[0] == '0' && str[1] == 'x') // No hexadecimal floats allowed
-        return false;
-    std::istringstream text(str);
-    text.imbue(std::locale::classic());
-    double result;
-    text >> result;
-    if(out) *out = result;
-    return text.eof() && !text.fail();
-}
-
 std::string FormatParagraph(const std::string& in, size_t width, size_t indent)
 {
     std::stringstream out;
diff --git a/src/util/strencodings.h b/src/util/strencodings.h
index 166352c42f..1f7762aeef 100644
--- a/src/util/strencodings.h
+++ b/src/util/strencodings.h
@@ -123,7 +123,9 @@ constexpr inline bool IsSpace(char c) noexcept {
 }
 
 /**
- * Convert string to integral type T.
+ * Convert string to integral type T. Leading whitespace, a leading +, or any
+ * trailing character fail the parsing. The required format expressed as regex
+ * is `-?[0-9]+`.
  *
  * @returns std::nullopt if the entire string could not be parsed, or if the
  *   parsed value is not in the range representable by the type T.
@@ -137,7 +139,7 @@ std::optional<T> ToIntegral(const std::string& str)
     if (first_nonmatching != str.data() + str.size() || error_condition != std::errc{}) {
         return std::nullopt;
     }
-    return {result};
+    return result;
 }
 
 /**
@@ -183,13 +185,6 @@ std::optional<T> ToIntegral(const std::string& str)
 [[nodiscard]] bool ParseUInt64(const std::string& str, uint64_t *out);
 
 /**
- * Convert string to double with strict parse error feedback.
- * @returns true if the entire string could be parsed as valid double,
- *   false if not the entire string could be parsed or when overflow or underflow occurred.
- */
-[[nodiscard]] bool ParseDouble(const std::string& str, double *out);
-
-/**
  * Convert a span of bytes to a lower-case hexadecimal string.
  */
 std::string HexStr(const Span<const uint8_t> s);