Use a raw string literal in the alt-string json_view test

clang-tidy (modernize-raw-string-literal) rejects the escaped literal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

.github/workflows/cancel_closed_pr_runs.yml

@@ -24,7 +24,7 @@ jobs:
     permissions:
       actions: write
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
 
     steps:
       - name: Harden Runner

.github/workflows/check_amalgamation.yml

@@ -19,7 +19,7 @@ permissions:
 jobs:
   save:
     if: github.event_name == 'pull_request'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@dc2769abcc0fcfbadfc1df54081c1608579ef6b2 # v2.22.2

.github/workflows/check_docs_links.yml

@@ -16,7 +16,7 @@ concurrency:
 jobs:
   check_docs_links:
     if: github.repository == 'nlohmann/json'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     timeout-minutes: 30
     steps:
       - name: Harden Runner

.github/workflows/comment_check_amalgamation.yml

@@ -12,7 +12,7 @@ jobs:
   comment:
     # push runs on develop have no PR to comment on (and no "pr" artifact)
     if: ${{ github.event.workflow_run.conclusion == 'failure' && github.event.workflow_run.event == 'pull_request' }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       contents: read
       actions: read

.github/workflows/dependency-review.yml

@@ -18,7 +18,7 @@ permissions:
 
 jobs:
   dependency-review:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@dc2769abcc0fcfbadfc1df54081c1608579ef6b2 # v2.22.2

.github/workflows/flawfinder.yml

@@ -24,7 +24,7 @@ on:
 jobs:
   flawfinder:
     name: Flawfinder
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       actions: read
       contents: read

.github/workflows/labeler.yml

@@ -19,7 +19,7 @@ jobs:
       contents: read
       pull-requests: write
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
 
     steps:
       - name: Harden Runner

.github/workflows/publish_documentation.yml

@@ -34,7 +34,7 @@ jobs:
       contents: write
 
     if: github.repository == 'nlohmann/json'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@dc2769abcc0fcfbadfc1df54081c1608579ef6b2 # v2.22.2

.github/workflows/scorecards.yml

@@ -24,7 +24,7 @@ permissions:
 jobs:
   analysis:
     name: Scorecard analysis
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     permissions:
       # Needed to upload the results to code-scanning dashboard.
       security-events: write

.github/workflows/stale.yml

@@ -8,7 +8,7 @@ permissions:
 
 jobs:
   stale:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
 
     permissions:
       issues: write

.github/workflows/ubuntu.yml

@@ -18,7 +18,7 @@ concurrency:
 
 jobs:
   ci_test_gcc:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: gcc:latest
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -130,7 +130,7 @@ jobs:
         run: cmake --build build --target ${{ matrix.target }}
 
   ci_static_analysis_clang:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: silkeh/clang:22
     strategy:
       matrix:
@@ -149,7 +149,7 @@ jobs:
         run: cmake --build build --target ${{ matrix.target }}
 
   ci_cmake_options:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: ubuntu:24.04
     strategy:
       matrix:
@@ -209,7 +209,7 @@ jobs:
           fail-on-error: false
 
   ci_test_compilers_gcc_old:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     strategy:
       matrix:
         compiler: ['4.8', '4.9', '5', '6']
@@ -251,7 +251,7 @@ jobs:
         run: cmake --build build --target ci_test_compiler_g++-${{ matrix.compiler }}
 
   ci_test_compilers_gcc:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     strategy:
       matrix:
         # older GCC docker images (4, 5, 6) fail to check out code
@@ -269,7 +269,7 @@ jobs:
         run: cmake --build build --target ci_test_compiler_default
 
   ci_test_compilers_clang:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     strategy:
       matrix:
         compiler: ['3.4', '3.5', '3.6', '3.7', '3.8', '3.9', '4', '5', '6', '7', '8', '9', '10', '11', '12', '13', '14', '15-bullseye', '16', '17', '18', '19', '20', '21', '22', 'latest']
@@ -289,7 +289,7 @@ jobs:
         run: cmake --build build --target ci_test_compiler_default
 
   ci_test_standards_gcc:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: gcc:latest
     strategy:
       matrix:
@@ -306,7 +306,7 @@ jobs:
         run: cmake --build build --target ci_test_gcc_cxx${{ matrix.standard }}
 
   ci_test_standards_clang:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: silkeh/clang:latest
     strategy:
       matrix:
@@ -330,7 +330,7 @@ jobs:
         if: ${{ matrix.stdlib == 'libstdcxx' }}
 
   ci_cuda_example:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     strategy:
       fail-fast: false
       matrix:
@@ -356,7 +356,7 @@ jobs:
     strategy:
       matrix:
         container: ['gcc:latest', 'silkeh/clang:latest']
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: ${{ matrix.container }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -383,7 +383,7 @@ jobs:
         run: cmake --build build --target ci_module_cpp20
 
   ci_icpc:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     # Intel discontinued the classic icc/icpc compiler in oneAPI 2024.0; this is
     # Intel's own last officially published image that still includes it.
     container: intel/oneapi-hpckit:2023.2.1-devel-ubuntu22.04
@@ -402,7 +402,7 @@ jobs:
         run: cmake --build build --target ci_icpc
 
   ci_icpx:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: intel/oneapi-hpckit:latest
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -416,7 +416,7 @@ jobs:
         run: cmake --build build --target ci_icpx
 
   ci_nvhpc:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     container: nvcr.io/nvidia/nvhpc:25.5-devel-cuda12.9-ubuntu22.04
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1

docs/mkdocs/docs/api/basic_json/insert.md

@@ -65,17 +65,7 @@ the same index, which is now a different value.
 
 ## Exception safety
 
-1. Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
+Strong exception safety: if an exception occurs, the original value stays intact.
-2. Basic guarantee: if an exception is thrown while the elements are copied (for example, `std::bad_alloc`), the JSON
-   value may be partially modified, but it stays a valid array.
-3. Basic guarantee: if an exception is thrown while the elements are copied (for example, `std::bad_alloc`), the JSON
-   value may be partially modified, but it stays a valid array.
-4. Basic guarantee: if an exception is thrown while the elements are copied (for example, `std::bad_alloc`), the JSON
-   value may be partially modified, but it stays a valid array.
-5. Basic guarantee: if an exception is thrown while the members are copied (for example, `std::bad_alloc`), the JSON
-   value may be partially modified, but it stays a valid object.
-
-The exceptions listed below are thrown before the JSON value is changed.
 
 ## Exceptions
 

docs/mkdocs/docs/features/types/template_parameters.md

@@ -406,6 +406,7 @@ using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
 | `#!cpp operator<<(std::ostream&, const json_pointer&)`                                                                            | streamability to `#!cpp std::ostream`                                                                                                                                                        |
 | [`to_string`](../../api/basic_json/to_string.md)                                                                                  | conversion of `StringType` to `#!cpp std::string` (the function returns a `#!cpp std::string`)                                                                                               |
 | exception messages                                                                                                                | `data()` and `size()`, or `begin()` and `end()`                                                                                                                                              |
+| [`basic_json_view::dump`](../../api/basic_json_view/dump.md)                                                                      | `reserve(n)` and `resize(n)` (one argument); `capacity()` is **not** required                                                                                                                |
 
 ### Compatible types
 

include/nlohmann/detail/input/binary_reader.hpp

@@ -467,11 +467,13 @@ class binary_reader
 
             const std::size_t element_type_parse_position = chars_read;
             // an array's elements are named "0", "1", ... in the wire format,
-            // and those names are not passed on: they are skipped unless
+            // and those names are not passed on: they are skipped, and only
-            // error_handler_t::strict must reject ill-formed UTF-8 in them
+            // checked if error_handler_t::strict must reject ill-formed UTF-8
             const bool is_object = container_stack.back().is_object;
             key.clear();
-            if (JSON_HEDLEY_UNLIKELY(!get_bson_cstr(key, is_object || error_handler == error_handler_t::strict)))
+            if (JSON_HEDLEY_UNLIKELY(!(is_object || error_handler != error_handler_t::strict
+                                       ? get_bson_cstr(key, is_object)
+                                       : check_bson_cstr(key, std::integral_constant<bool, bulk_scan> {}))))
             {
                 return false;
             }
@@ -495,7 +497,7 @@ class binary_reader
     @param[in] store  whether the characters are needed; if not (the names of
                       an array's elements), they are skipped and @a result may
                       be left unchanged, and they are not checked against
-                      @ref error_handler
+                      @ref error_handler (@ref check_bson_cstr checks them)
     @return `true` if the \\x00-byte indicating the end of the string was
              encountered before the EOF; false` indicates an unexpected EOF.
     */
@@ -554,6 +556,42 @@ class binary_reader
         return true;
     }
 
+    /*!
+    @brief skip a C-style string that error_handler_t::strict must check
+
+    The names of an array's elements are not passed on. On contiguous input,
+    a well-formed name is checked in place and skipped without being copied.
+    Otherwise (no \\x00-byte in the input that can be scanned, or ill-formed
+    UTF-8), it is read by @ref get_bson_cstr, which reports the error.
+
+    @param[in,out] result  an empty string, which may receive the name
+    @return whether the name was read and is well-formed
+    */
+    bool check_bson_cstr(string_t& result, std::true_type /*bulk*/)
+    {
+        const std::size_t remaining = ia.bulk_remaining();
+        if (remaining != 0)
+        {
+            const auto* const data = reinterpret_cast<const unsigned char*>(ia.bulk_data());
+            const std::size_t length = find_zero_byte(data, remaining);
+            if (length != remaining && JSON_HEDLEY_LIKELY(valid_utf8_string(data, length)))
+            {
+                // consume the string and its \x00-byte, as get_bson_cstr does
+                ia.bulk_skip(length + 1);
+                chars_read += length + 1;
+                current = 0x00;
+                return true;
+            }
+        }
+        return get_bson_cstr(result);
+    }
+
+    /// input that is not contiguous: the name is read and checked byte by byte
+    bool check_bson_cstr(string_t& result, std::false_type /*bulk*/)
+    {
+        return get_bson_cstr(result);
+    }
+
     /// input that is not contiguous: C-style strings are read byte by byte
     bool get_bson_cstr_bulk(string_t& /*result*/, const bool /*store*/, std::false_type /*bulk*/) const noexcept
     {

include/nlohmann/detail/view/serializer.hpp

@@ -47,6 +47,7 @@ class output_buffer
         : m_out(sized(out, estimate))
         , m_pos(&m_out[0])
         , m_end(m_pos + m_out.size())
+        , m_reserved((std::max)(estimate, m_out.size()))
     {}
 
     void finish()
@@ -116,11 +117,12 @@ class output_buffer
         const auto used = static_cast<std::size_t>(m_pos - m_out.data());
         // (a step does not go beyond the reserved estimate, so that a good
         // estimate is never copied to a larger allocation; not a clamp: the
-        // lower bound used + n + 256 can exceed capacity(), and then it must win)
+        // lower bound used + n + 256 can exceed m_reserved, and then it must win)
-        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_out.capacity()), used + n + 256);
+        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_reserved), used + n + 256);
-        if (size > m_out.capacity())
+        if (size > m_reserved)
         {
-            m_out.reserve((std::max)(m_out.capacity() * 2, size));
+            m_reserved = (std::max)(m_reserved * 2, size);
+            m_out.reserve(m_reserved);
         }
         m_out.resize(size);
         m_pos = &m_out[0] + used;
@@ -130,6 +132,9 @@ class output_buffer
     StringType& m_out;
     char* m_pos;
     char* m_end;
+    /// what was last passed to reserve(), a lower bound of the capacity
+    /// (StringType need not have a capacity() member)
+    std::size_t m_reserved;
 };
 
 /// The length of the run at s that dump() writes unchanged without

include/nlohmann/json.hpp

@@ -4914,30 +4914,6 @@ public:
         return {it, res.second};
     }
 
-  private:
-    /// Sets the parents of a value when it goes out of scope, also when an
-    /// exception is thrown: a container insertion that throws may already
-    /// have added elements, whose parents must be set for the value to stay
-    /// valid (basic exception guarantee). Does nothing without JSON_DIAGNOSTICS.
-    class set_parents_on_exit
-    {
-      public:
-        explicit set_parents_on_exit(basic_json* v) noexcept : m_value(v) {}
-        set_parents_on_exit(const set_parents_on_exit&) = delete;
-        set_parents_on_exit& operator=(const set_parents_on_exit&) = delete;
-        set_parents_on_exit(set_parents_on_exit&&) = delete;
-        set_parents_on_exit& operator=(set_parents_on_exit&&) = delete;
-
-        ~set_parents_on_exit()
-        {
-            m_value->set_parents();
-        }
-
-      private:
-        basic_json* m_value;
-    };
-
-  public:
     /// Helper for insertion of an iterator
     /// @note: This uses std::distance to support GCC 4.8,
     ///        see https://github.com/nlohmann/json/pull/1257
@@ -4947,7 +4923,6 @@ public:
         iterator result(this);
         JSON_ASSERT(m_data.m_value.array != nullptr);
 
-        const set_parents_on_exit parents(this);
         auto insert_pos = std::distance(m_data.m_value.array->begin(), pos.m_it.array_iterator);
         m_data.m_value.array->insert(pos.m_it.array_iterator, std::forward<Args>(args)...);
         result.m_it.array_iterator = m_data.m_value.array->begin() + insert_pos;
@@ -4956,6 +4931,7 @@ public:
         // result.m_it.array_iterator = m_data.m_value.array->insert(pos.m_it.array_iterator, cnt, val);
         // but the return value of insert is missing in GCC 4.8, so it is written this way instead.
 
+        set_parents();
         return result;
     }
 
@@ -4975,16 +4951,8 @@ public:
             throw_iterator_from_other_value(this);
         }
 
-        // vector::insert has no effects if copying a single element to the
+        // insert to array and return iterator
-        // end throws; elsewhere, it may already have shifted the elements, so
+        return insert_iterator(pos, val);
-        // copy first and insert by move, which cannot throw but by allocating
-        if (pos.m_it.array_iterator == m_data.m_value.array->end())
-        {
-            return insert_iterator(pos, val);
-        }
-
-        basic_json tmp(val);
-        return insert_iterator(pos, std::move(tmp));
     }
 
     /// @brief inserts element into array
@@ -5116,8 +5084,8 @@ public:
             detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterators first and last must point to objects", this);
         }
 
-        const set_parents_on_exit parents(this);
         m_data.m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator);
+        set_parents();
     }
 
     /// @brief updates a JSON object from another object, overwriting existing keys

single_include/nlohmann/json.hpp

@@ -18474,11 +18474,13 @@ class binary_reader
 
             const std::size_t element_type_parse_position = chars_read;
             // an array's elements are named "0", "1", ... in the wire format,
-            // and those names are not passed on: they are skipped unless
+            // and those names are not passed on: they are skipped, and only
-            // error_handler_t::strict must reject ill-formed UTF-8 in them
+            // checked if error_handler_t::strict must reject ill-formed UTF-8
             const bool is_object = container_stack.back().is_object;
             key.clear();
-            if (JSON_HEDLEY_UNLIKELY(!get_bson_cstr(key, is_object || error_handler == error_handler_t::strict)))
+            if (JSON_HEDLEY_UNLIKELY(!(is_object || error_handler != error_handler_t::strict
+                                       ? get_bson_cstr(key, is_object)
+                                       : check_bson_cstr(key, std::integral_constant<bool, bulk_scan> {}))))
             {
                 return false;
             }
@@ -18502,7 +18504,7 @@ class binary_reader
     @param[in] store  whether the characters are needed; if not (the names of
                       an array's elements), they are skipped and @a result may
                       be left unchanged, and they are not checked against
-                      @ref error_handler
+                      @ref error_handler (@ref check_bson_cstr checks them)
     @return `true` if the \\x00-byte indicating the end of the string was
              encountered before the EOF; false` indicates an unexpected EOF.
     */
@@ -18561,6 +18563,42 @@ class binary_reader
         return true;
     }
 
+    /*!
+    @brief skip a C-style string that error_handler_t::strict must check
+
+    The names of an array's elements are not passed on. On contiguous input,
+    a well-formed name is checked in place and skipped without being copied.
+    Otherwise (no \\x00-byte in the input that can be scanned, or ill-formed
+    UTF-8), it is read by @ref get_bson_cstr, which reports the error.
+
+    @param[in,out] result  an empty string, which may receive the name
+    @return whether the name was read and is well-formed
+    */
+    bool check_bson_cstr(string_t& result, std::true_type /*bulk*/)
+    {
+        const std::size_t remaining = ia.bulk_remaining();
+        if (remaining != 0)
+        {
+            const auto* const data = reinterpret_cast<const unsigned char*>(ia.bulk_data());
+            const std::size_t length = find_zero_byte(data, remaining);
+            if (length != remaining && JSON_HEDLEY_LIKELY(valid_utf8_string(data, length)))
+            {
+                // consume the string and its \x00-byte, as get_bson_cstr does
+                ia.bulk_skip(length + 1);
+                chars_read += length + 1;
+                current = 0x00;
+                return true;
+            }
+        }
+        return get_bson_cstr(result);
+    }
+
+    /// input that is not contiguous: the name is read and checked byte by byte
+    bool check_bson_cstr(string_t& result, std::false_type /*bulk*/)
+    {
+        return get_bson_cstr(result);
+    }
+
     /// input that is not contiguous: C-style strings are read byte by byte
     bool get_bson_cstr_bulk(string_t& /*result*/, const bool /*store*/, std::false_type /*bulk*/) const noexcept
     {
@@ -42706,30 +42744,6 @@ public:
         return {it, res.second};
     }
 
-  private:
-    /// Sets the parents of a value when it goes out of scope, also when an
-    /// exception is thrown: a container insertion that throws may already
-    /// have added elements, whose parents must be set for the value to stay
-    /// valid (basic exception guarantee). Does nothing without JSON_DIAGNOSTICS.
-    class set_parents_on_exit
-    {
-      public:
-        explicit set_parents_on_exit(basic_json* v) noexcept : m_value(v) {}
-        set_parents_on_exit(const set_parents_on_exit&) = delete;
-        set_parents_on_exit& operator=(const set_parents_on_exit&) = delete;
-        set_parents_on_exit(set_parents_on_exit&&) = delete;
-        set_parents_on_exit& operator=(set_parents_on_exit&&) = delete;
-
-        ~set_parents_on_exit()
-        {
-            m_value->set_parents();
-        }
-
-      private:
-        basic_json* m_value;
-    };
-
-  public:
     /// Helper for insertion of an iterator
     /// @note: This uses std::distance to support GCC 4.8,
     ///        see https://github.com/nlohmann/json/pull/1257
@@ -42739,7 +42753,6 @@ public:
         iterator result(this);
         JSON_ASSERT(m_data.m_value.array != nullptr);
 
-        const set_parents_on_exit parents(this);
         auto insert_pos = std::distance(m_data.m_value.array->begin(), pos.m_it.array_iterator);
         m_data.m_value.array->insert(pos.m_it.array_iterator, std::forward<Args>(args)...);
         result.m_it.array_iterator = m_data.m_value.array->begin() + insert_pos;
@@ -42748,6 +42761,7 @@ public:
         // result.m_it.array_iterator = m_data.m_value.array->insert(pos.m_it.array_iterator, cnt, val);
         // but the return value of insert is missing in GCC 4.8, so it is written this way instead.
 
+        set_parents();
         return result;
     }
 
@@ -42767,16 +42781,8 @@ public:
             throw_iterator_from_other_value(this);
         }
 
-        // vector::insert has no effects if copying a single element to the
+        // insert to array and return iterator
-        // end throws; elsewhere, it may already have shifted the elements, so
+        return insert_iterator(pos, val);
-        // copy first and insert by move, which cannot throw but by allocating
-        if (pos.m_it.array_iterator == m_data.m_value.array->end())
-        {
-            return insert_iterator(pos, val);
-        }
-
-        basic_json tmp(val);
-        return insert_iterator(pos, std::move(tmp));
     }
 
     /// @brief inserts element into array
@@ -42908,8 +42914,8 @@ public:
             detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterators first and last must point to objects", this);
         }
 
-        const set_parents_on_exit parents(this);
         m_data.m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator);
+        set_parents();
     }
 
     /// @brief updates a JSON object from another object, overwriting existing keys

single_include/nlohmann/json_view.hpp

@@ -8511,6 +8511,7 @@ class output_buffer
         : m_out(sized(out, estimate))
         , m_pos(&m_out[0])
         , m_end(m_pos + m_out.size())
+        , m_reserved((std::max)(estimate, m_out.size()))
     {}
 
     void finish()
@@ -8580,11 +8581,12 @@ class output_buffer
         const auto used = static_cast<std::size_t>(m_pos - m_out.data());
         // (a step does not go beyond the reserved estimate, so that a good
         // estimate is never copied to a larger allocation; not a clamp: the
-        // lower bound used + n + 256 can exceed capacity(), and then it must win)
+        // lower bound used + n + 256 can exceed m_reserved, and then it must win)
-        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_out.capacity()), used + n + 256);
+        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_reserved), used + n + 256);
-        if (size > m_out.capacity())
+        if (size > m_reserved)
         {
-            m_out.reserve((std::max)(m_out.capacity() * 2, size));
+            m_reserved = (std::max)(m_reserved * 2, size);
+            m_out.reserve(m_reserved);
         }
         m_out.resize(size);
         m_pos = &m_out[0] + used;
@@ -8594,6 +8596,9 @@ class output_buffer
     StringType& m_out;
     char* m_pos;
     char* m_end;
+    /// what was last passed to reserve(), a lower bound of the capacity
+    /// (StringType need not have a capacity() member)
+    std::size_t m_reserved;
 };
 
 /// The length of the run at s that dump() writes unchanged without

tests/src/unit-allocator.cpp

@@ -12,7 +12,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
-#include <functional>
 #include <valarray>
 #if JSON_HAS_RANGES
     #include <ranges>
@@ -805,222 +804,3 @@ TEST_CASE("a failed allocation leaves the value unchanged")
 #endif
 }
 #endif
-
-// the no-exceptions CI job has no std::bad_alloc to catch; with iterator
-// debugging (MSVC STL debug builds) containers allocate inside noexcept
-// functions, so failing an allocation there terminates the program
-#if !defined(JSON_NOEXCEPTION) && !(defined(_ITERATOR_DEBUG_LEVEL) && _ITERATOR_DEBUG_LEVEL > 0)
-namespace
-{
-// whether every child of j names j as its parent (always true without
-// JSON_DIAGNOSTICS, where no parents are stored)
-template<class BasicJsonType>
-bool children_name_their_parent(const BasicJsonType& j)
-{
-#if JSON_DIAGNOSTICS
-    if (j.is_array())
-    {
-        for (const auto& element : *j.m_data.m_value.array)
-        {
-            if (element.m_parent != &j)
-            {
-                return false;
-            }
-        }
-    }
-    else if (j.is_object())
-    {
-        for (const auto& element : *j.m_data.m_value.object)
-        {
-            if (element.second.m_parent != &j)
-            {
-                return false;
-            }
-        }
-    }
-#else
-    static_cast<void>(j);
-#endif
-    return true;
-}
-
-enum class guarantee
-{
-    basic, // the value stays valid and keeps its type
-    strong // the value is unchanged
-};
-
-// Runs op on a fresh value make() with the 0th, 1st, 2nd, ... allocation made
-// by the library failing in turn, until op completes. Every failed attempt
-// must have thrown std::bad_alloc and left the value valid, with all parent
-// pointers intact (copying a value asserts the invariant), and for the strong
-// guarantee exactly as it was.
-template<class BasicJsonType>
-void check_exception_guarantee(guarantee g,
-                               const std::function<BasicJsonType()>& make,
-                               const std::function<void(BasicJsonType&)>& op)
-{
-    fail_at_alloc_call = -1;
-
-    bool completed = false;
-    std::size_t failures = 0;
-    for (std::size_t n = 0; !completed; ++n)
-    {
-        CAPTURE(n)
-        REQUIRE(n < 1000);
-
-        BasicJsonType j = make();
-        const std::string before = j.dump();
-        const auto type_before = j.type();
-
-        alloc_call_count = 0;
-        fail_at_alloc_call = static_cast<long>(n);
-        try
-        {
-            op(j);
-            completed = true;
-        }
-        catch (const std::bad_alloc&)
-        {
-            ++failures;
-        }
-        fail_at_alloc_call = -1;
-
-        if (!completed)
-        {
-            CHECK((j.type() == type_before));
-            CHECK(children_name_their_parent(j));
-            const BasicJsonType copy(j); // NOLINT(performance-unnecessary-copy-initialization): the copy is the point, it allocates
-            CHECK(copy.dump() == j.dump());
-            if (g == guarantee::strong)
-            {
-                CHECK(j.dump() == before);
-            }
-        }
-    }
-
-    // the operation allocates, so at least one attempt must have failed
-    CHECK(failures > 0);
-}
-
-template<class BasicJsonType>
-void check_insert_exception_guarantees()
-{
-    using json_t = BasicJsonType;
-    using make_t = std::function<json_t()>;
-
-    // strings of this length do not fit into the small string buffer, so
-    // copying them allocates
-    const json_t val = std::string(64, 'x');
-    const json_t source = json_t::array({std::string(64, 'p'), std::string(64, 'q'), std::string(64, 'r')});
-
-    for (const bool spare_capacity :
-            {
-                false, true
-            })
-    {
-        CAPTURE(spare_capacity)
-
-        // [ "aaa...", "bbb...", "ccc..." ], with a spare slot if requested
-        const make_t make = [spare_capacity]()
-        {
-            json_t j = json_t::array({std::string(64, 'a'), std::string(64, 'b'), std::string(64, 'c')});
-            if (spare_capacity)
-            {
-                j.push_back(std::string(64, 'd'));
-                j.erase(3);
-            }
-            return json_t(std::move(j));
-        };
-
-        for (const bool at_end :
-                {
-                    false, true
-                })
-        {
-            CAPTURE(at_end)
-
-            SECTION("insert(pos, const basic_json&)")
-            {
-                check_exception_guarantee<json_t>(guarantee::strong, make, [&](json_t& j)
-                {
-                    j.insert(at_end ? j.end() : j.begin() + 1, val);
-                });
-            }
-
-            SECTION("insert(pos, basic_json&&)")
-            {
-                check_exception_guarantee<json_t>(guarantee::strong, make, [&](json_t& j)
-                {
-                    j.insert(at_end ? j.end() : j.begin() + 1, json_t(val));
-                });
-            }
-
-            SECTION("insert(pos, size_type, const basic_json&)")
-            {
-                check_exception_guarantee<json_t>(guarantee::basic, make, [&](json_t& j)
-                {
-                    j.insert(at_end ? j.end() : j.begin() + 1, 3, val);
-                });
-            }
-
-            SECTION("insert(pos, const_iterator, const_iterator)")
-            {
-                check_exception_guarantee<json_t>(guarantee::basic, make, [&](json_t& j)
-                {
-                    j.insert(at_end ? j.end() : j.begin() + 1, source.begin(), source.end());
-                });
-            }
-
-            SECTION("insert(pos, initializer_list_t)")
-            {
-                check_exception_guarantee<json_t>(guarantee::basic, make, [&](json_t& j)
-                {
-                    j.insert(at_end ? j.end() : j.begin() + 1, {val, val});
-                });
-            }
-        }
-    }
-
-    SECTION("insert(const_iterator, const_iterator) for objects")
-    {
-        const json_t members = {{"m", std::string(64, 'm')}, {"n", std::string(64, 'n')}, {"o", std::string(64, 'o')}};
-
-        SECTION("no member exists yet")
-        {
-            check_exception_guarantee<json_t>(guarantee::basic, []()
-            {
-                return json_t({{"a", 1}});
-            }, [&](json_t& j)
-            {
-                j.insert(members.begin(), members.end());
-            });
-        }
-
-        SECTION("some members exist already")
-        {
-            check_exception_guarantee<json_t>(guarantee::basic, []()
-            {
-                return json_t({{"a", 1}, {"n", std::string(64, 'x')}});
-            }, [&](json_t& j)
-            {
-                j.insert(members.begin(), members.end());
-            });
-        }
-    }
-}
-} // namespace
-
-TEST_CASE("insert() provides its documented exception guarantees (#5986)")
-{
-    SECTION("std::map-backed object_t")
-    {
-        check_insert_exception_guarantees<nlohmann::json::with_allocator_t<nth_alloc_fails_allocator>>();
-    }
-
-    SECTION("ordered_map-backed object_t")
-    {
-        check_insert_exception_guarantees<nlohmann::ordered_json::with_allocator_t<nth_alloc_fails_allocator>>();
-    }
-}
-#endif

tests/src/unit-alt-string.cpp

@@ -10,6 +10,7 @@
 #include "doctest_compatibility.h"
 
 #include <nlohmann/json.hpp>
+#include <nlohmann/json_view.hpp>
 
 #include <cstdint>
 #include <string>
@@ -483,4 +484,56 @@ TEST_CASE("alternative string type")
     }
 }
 
+TEST_CASE("alternative string type with json_view")
+{
+    // regression test for #5994: basic_json_view::dump() called
+    // StringType::capacity(), which alt_string (and the documented StringType
+    // requirements) do not provide
+    using alt_document = nlohmann::basic_json_document<alt_json, nlohmann::view_mode::read_only>;
+    using alt_editable_document = nlohmann::basic_json_document<alt_json, nlohmann::view_mode::editable>;
+
+    const char* text = R"({"a":[1,"x\u00e4"],"b":{"c":true,"d":null},"e":2.5})";
+    const alt_json j = alt_json::parse(text);
+
+    SECTION("read-only document")
+    {
+        const alt_document d = alt_document::parse(text);
+        CHECK(d.root().dump() == j.dump());
+        CHECK(d.root().dump(2) == j.dump(2));
+        CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
+        CHECK(d.root().materialize() == j);
+        CHECK(d.root().contains(alt_string("b")));
+        CHECK(d.root()[alt_string("b")][alt_string("c")].dump() == "true");
+    }
+
+    SECTION("long output")
+    {
+        // more than one growth step of the output buffer
+        alt_json big = alt_json::array();
+        for (int i = 0; i < 20000; ++i)
+        {
+            big.push_back(alt_json::parse(text));
+        }
+        const alt_string big_text = big.dump();
+        const alt_document d = alt_document::parse(big_text);
+        CHECK(d.root().dump() == big_text);
+        CHECK(d.root().dump(4) == big.dump(4));
+    }
+
+    SECTION("editable document")
+    {
+        alt_editable_document d = alt_editable_document::parse(text);
+        d.set(d.root(), "f", "new");
+        d.push_back(d.root()[alt_string("a")], 3);
+        alt_json expected = j;
+        expected["f"] = "new";
+        expected["a"].push_back(3);
+        CHECK(d.root().materialize() == expected);
+        CHECK(alt_json::parse(d.root().dump()) == expected);
+
+        const alt_editable_document loaded = alt_editable_document::load(d.save());
+        CHECK(loaded.root().materialize() == expected);
+    }
+}
+
 DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-bson.cpp

@@ -23,6 +23,7 @@ using nlohmann::json;
 #include <cstdint>
 #include <fstream>
 #include <limits>
+#include <list>
 #include <sstream>
 #include <vector>
 #include "make_test_data_available.hpp"
@@ -1199,6 +1200,31 @@ TEST_CASE("BSON keys from contiguous and stream input")
             from_stream = e.what();
         }
         CHECK(from_vector == from_stream);
+
+        // error_handler_t::strict checks the array element names in place on
+        // contiguous input and byte by byte otherwise; the names are
+        // well-formed, so both give the same value or error as above
+        std::string strict_from_vector;
+        std::string strict_from_list;
+        try
+        {
+            strict_from_vector = json::from_bson(input, true, true, json::error_handler_t::strict).dump();
+        }
+        catch (const json::parse_error& e)
+        {
+            strict_from_vector = e.what();
+        }
+        try
+        {
+            const std::list<std::uint8_t> list(input.begin(), input.end());
+            strict_from_list = json::from_bson(list.begin(), list.end(), true, true, json::error_handler_t::strict).dump();
+        }
+        catch (const json::parse_error& e)
+        {
+            strict_from_list = e.what();
+        }
+        CHECK(strict_from_vector == from_vector);
+        CHECK(strict_from_list == from_vector);
     }
 }
 
@@ -1227,6 +1253,18 @@ TEST_CASE("BSON array element names")
 
     std::istringstream stream(std::string(reinterpret_cast<const char*>(bson.data()), bson.size()));
     CHECK(json::from_bson(stream) == expected);
+
+    // input that is not contiguous reads the names byte by byte and must reject
+    // the same name
+    const std::list<std::uint8_t> list(bson.begin(), bson.end());
+    CHECK_THROWS_WITH_AS(_ = json::from_bson(list.begin(), list.end(), true, true, json::error_handler_t::strict), "[json.exception.parse_error.113] parse error at byte 14: syntax error while parsing BSON key: invalid string: ill-formed UTF-8 byte", json::parse_error&);
+
+    // without exceptions, the rejected name ends the parse
+    CHECK(json::from_bson(bson, true, false, json::error_handler_t::strict).is_discarded());
+
+    // well-formed names pass the check without being stored
+    const json valid = {{"a", {true, false, {{"k", json::array({1, 2})}}}}};
+    CHECK(json::from_bson(json::to_bson(valid), true, true, json::error_handler_t::strict) == valid);
 }
 #endif