Adding 4.8 test to travis

.github/CONTRIBUTING.md

@@ -54,7 +54,7 @@ To make changes, you need to edit the following files:
 
 ## Please don't
 
-- The C++11 support varies between different **compilers** and versions. Please note the [list of supported compilers](https://github.com/nlohmann/json/blob/master/README.md#supported-compilers). Some compilers like GCC 4.8 (and earlier), Clang 3.3 (and earlier), or Microsoft Visual Studio 13.0 and earlier are known not to work due to missing or incomplete C++11 support. Please refrain from proposing changes that work around these compiler's limitations with `#ifdef`s or other means.
+- The C++11 support varies between different **compilers** and versions. Please note the [list of supported compilers](https://github.com/nlohmann/json/blob/master/README.md#supported-compilers). Some compilers like GCC 4.7 (and earlier), Clang 3.3 (and earlier), or Microsoft Visual Studio 13.0 and earlier are known not to work due to missing or incomplete C++11 support. Please refrain from proposing changes that work around these compiler's limitations with `#ifdef`s or other means.
 - Specifically, I am aware of compilation problems with **Microsoft Visual Studio** (there even is an [issue label](https://github.com/nlohmann/json/issues?utf8=✓&q=label%3A%22visual+studio%22+) for these kind of bugs). I understand that even in 2016, complete C++11 support isn't there yet. But please also understand that I do not want to drop features or uglify the code just to make Microsoft's sub-standard compiler happy. The past has shown that there are ways to express the functionality such that the code compiles with the most recent MSVC - unfortunately, this is not the main objective of the project.
 - Please refrain from proposing changes that would **break [JSON](http://json.org) conformance**. If you propose a conformant extension of JSON to be supported by the library, please motivate this extension.
   - We shall not extend the library to **support comments**. There is quite some [controversy](https://www.reddit.com/r/programming/comments/4v6chu/why_json_doesnt_support_comments_douglas_crockford/) around this topic, and there were quite some [issues](https://github.com/nlohmann/json/issues/376) on this. We believe that JSON is fine without comments.

.github/PULL_REQUEST_TEMPLATE.md

@@ -13,7 +13,7 @@ Read the [Contribution Guidelines](https://github.com/nlohmann/json/blob/develop
 
 ## Please don't
 
-- The C++11 support varies between different **compilers** and versions. Please note the [list of supported compilers](https://github.com/nlohmann/json/blob/master/README.md#supported-compilers). Some compilers like GCC 4.8 (and earlier), Clang 3.3 (and earlier), or Microsoft Visual Studio 13.0 and earlier are known not to work due to missing or incomplete C++11 support. Please refrain from proposing changes that work around these compiler's limitations with `#ifdef`s or other means.
+- The C++11 support varies between different **compilers** and versions. Please note the [list of supported compilers](https://github.com/nlohmann/json/blob/master/README.md#supported-compilers). Some compilers like GCC 4.7 (and earlier), Clang 3.3 (and earlier), or Microsoft Visual Studio 13.0 and earlier are known not to work due to missing or incomplete C++11 support. Please refrain from proposing changes that work around these compiler's limitations with `#ifdef`s or other means.
 - Specifically, I am aware of compilation problems with **Microsoft Visual Studio** (there even is an [issue label](https://github.com/nlohmann/json/issues?utf8=✓&q=label%3A%22visual+studio%22+) for these kind of bugs). I understand that even in 2016, complete C++11 support isn't there yet. But please also understand that I do not want to drop features or uglify the code just to make Microsoft's sub-standard compiler happy. The past has shown that there are ways to express the functionality such that the code compiles with the most recent MSVC - unfortunately, this is not the main objective of the project.
 - Please refrain from proposing changes that would **break [JSON](http://json.org) conformance**. If you propose a conformant extension of JSON to be supported by the library, please motivate this extension.
 - Please do not open pull requests that address **multiple issues**.

.travis.yml

@@ -168,7 +168,15 @@ matrix:
 
   - os: linux
     compiler: gcc
-    env: COMPILER=g++-4.9
+    env: compiler=g++-4.8
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test']
+        packages: ['g++-4.8', 'ninja-build']
+
+  - os: linux
+    compiler: gcc
+    env: compiler=g++-4.9
     addons:
       apt:
         sources: ['ubuntu-toolchain-r-test']

README.md

@@ -843,7 +843,7 @@ json j_from_ubjson = json::from_ubjson(v_ubjson);
 
 Though it's 2018 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
 
-- GCC 4.9 - 8.2 (and possibly later)
+- GCC 4.8 - 8.2 (and possibly later)
 - Clang 3.4 - 6.1 (and possibly later)
 - Intel C++ Compiler 17.0.2 (and possibly later)
 - Microsoft Visual C++ 2015 / Build Tools 14.0.25123.0 (and possibly later)
@@ -853,7 +853,7 @@ I would be happy to learn about other compilers/versions.
 
 Please note:
 
-- GCC 4.8 does not work because of two bugs ([55817](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55817) and [57824](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57824)) in the C++11 support. Note there is a [pull request](https://github.com/nlohmann/json/pull/212) to fix some of the issues.
+- GCC 4.8 has a bug [57824](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57824)): multiline raw strings cannot be the arguments to macros. Don't use multiline raw strings directly in macros with this compiler.
 - Android defaults to using very old compilers and C++ libraries. To fix this, add the following to your `Application.mk`. This will switch to the LLVM C++ library, the Clang compiler, and enable C++11 and other features disabled by default.
 
     ```
@@ -872,6 +872,7 @@ The following compilers are currently used in continuous integration at [Travis]
 
 | Compiler        | Operating System             | Version String |
 |-----------------|------------------------------|----------------|
+| GCC 4.8.5       | Ubuntu 14.04.5 LTS           | g++-4.8 (Ubuntu 4.8.5-2ubuntu1~14.04.2) 4.8.5 |
 | GCC 4.9.4       | Ubuntu 14.04.1 LTS           | g++-4.9 (Ubuntu 4.9.4-2ubuntu1~14.04.1) 4.9.4 |
 | GCC 5.5.0       | Ubuntu 14.04.1 LTS           | g++-5 (Ubuntu 5.5.0-12ubuntu1~14.04) 5.5.0 20171010 |
 | GCC 6.4.0       | Ubuntu 14.04.1 LTS           | g++-6 (Ubuntu 6.4.0-17ubuntu1~14.04) 6.4.0 20180424 |

include/nlohmann/json.hpp

@@ -4943,7 +4943,9 @@ class basic_json
         return {it, res.second};
     }
 
-    /// helper for insertion of an iterator (supports GCC 4.8+)
+    /// Helper for insertion of an iterator
+    /// @note: This uses std::distance to support GCC 4.8,
+    ///        see https://github.com/nlohmann/json/pull/1257
     template<typename... Args>
     iterator insert_iterator(const_iterator pos, Args&& ... args)
     {
@@ -4954,8 +4956,9 @@ class basic_json
         m_value.array->insert(pos.m_it.array_iterator, std::forward<Args>(args)...);
         result.m_it.array_iterator = m_value.array->begin() + insert_pos;
 
-        // For GCC 4.9+ only, this could become:
+        // This could have been written as:
         // result.m_it.array_iterator = 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.
 
         return result;
     }

single_include/nlohmann/json.hpp

@@ -16016,7 +16016,9 @@ class basic_json
         return {it, res.second};
     }
 
-    /// helper for insertion of an iterator (supports GCC 4.8+)
+    /// Helper for insertion of an iterator
+    /// @note: This uses std::distance to support GCC 4.8,
+    ///        see https://github.com/nlohmann/json/pull/1257
     template<typename... Args>
     iterator insert_iterator(const_iterator pos, Args&& ... args)
     {
@@ -16027,8 +16029,9 @@ class basic_json
         m_value.array->insert(pos.m_it.array_iterator, std::forward<Args>(args)...);
         result.m_it.array_iterator = m_value.array->begin() + insert_pos;
 
-        // For GCC 4.9+ only, this could become:
+        // This could have been written as:
         // result.m_it.array_iterator = 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.
 
         return result;
     }

test/src/unit-json_patch.cpp

@@ -63,7 +63,7 @@ TEST_CASE("JSON patch")
             // is not an error, because "a" exists, and "b" will be added to
             // its value.
             CHECK_NOTHROW(doc1.patch(patch));
-            CHECK(doc1.patch(patch) == R"(
+            auto doc1_ans = R"(
                 {
                     "a": {
                         "foo": 1,
@@ -72,7 +72,8 @@ TEST_CASE("JSON patch")
                         }
                     }
                 }
-            )"_json);
+            )"_json;
+            CHECK(doc1.patch(patch) == doc1_ans);
 
             // It is an error in this document:
             json doc2 = R"({ "q": { "bar": 2 } })"_json;

test/src/unit-regression.cpp

@@ -1427,20 +1427,26 @@ TEST_CASE("regression tests")
             }
         })"_json;
 
-        CHECK_THROWS_AS(model.patch(R"([{"op": "move",
+        auto p1 = R"([{"op": "move",
-                         "from": "/one/two/three",
+                       "from": "/one/two/three",
-                         "path": "/a/b/c"}])"_json), json::out_of_range&);
+                       "path": "/a/b/c"}])"_json;
-        CHECK_THROWS_WITH(model.patch(R"([{"op": "move",
+        CHECK_THROWS_AS(model.patch(p1), json::out_of_range&);
-                         "from": "/one/two/three",
+
-                         "path": "/a/b/c"}])"_json),
+        auto p2 = R"([{"op": "move",
+                       "from": "/one/two/three",
+                       "path": "/a/b/c"}])"_json;
+        CHECK_THROWS_WITH(model.patch(p2),
                           "[json.exception.out_of_range.403] key 'a' not found");
 
-        CHECK_THROWS_AS(model.patch(R"([{"op": "copy",
+        auto p3 = R"([{"op": "copy",
+                       "from": "/one/two/three",
+                       "path": "/a/b/c"}])"_json;
+        CHECK_THROWS_AS(model.patch(p3), json::out_of_range&);
+
+        auto p4 = R"([{"op": "copy",
                                  "from": "/one/two/three",
-                                 "path": "/a/b/c"}])"_json), json::out_of_range&);
+                                 "path": "/a/b/c"}])"_json;
-        CHECK_THROWS_WITH(model.patch(R"([{"op": "copy",
+        CHECK_THROWS_WITH(model.patch(p4),
-                                 "from": "/one/two/three",
-                                 "path": "/a/b/c"}])"_json),
                           "[json.exception.out_of_range.403] key 'a' not found");
     }
 

test/src/unit-testsuites.cpp

@@ -405,7 +405,7 @@ TEST_CASE("RFC 7159 examples")
     SECTION("13 Examples")
     {
         {
-            CHECK_NOTHROW(json(R"(
+            auto json_contents = R"(
             {
                  "Image": {
                      "Width":  800,
@@ -420,11 +420,13 @@ TEST_CASE("RFC 7159 examples")
                      "IDs": [116, 943, 234, 38793]
                    }
                }
-            )"));
+            )";
+
+            CHECK_NOTHROW(json(json_contents));
         }
 
         {
-            CHECK_NOTHROW(json(R"(
+            auto json_contents = R"(
                 [
                     {
                        "precision": "zip",
@@ -446,7 +448,8 @@ TEST_CASE("RFC 7159 examples")
                        "Zip":       "94085",
                        "Country":   "US"
                     }
-            ])"));
+            ])";
+            CHECK_NOTHROW(json(json_contents));
         }
 
         CHECK(json::parse("\"Hello world!\"") == json("Hello world!"));