This patch is from the upstream pull request
https://github.com/chadaustin/sajson/pull/54.
It fixes linking with GCC.

diff --git a/include/sajson.h b/include/sajson.h
index 8b4e05a..1bd045b 100644
--- a/include/sajson.h
+++ b/include/sajson.h
@@ -138,12 +138,17 @@ constexpr inline size_t make_element(tag t, size_t value) {
 // header. This trick courtesy of Rich Geldreich's Purple JSON parser.
 template <typename unused = void>
 struct globals_struct {
+    static const unsigned char parse_flags[256];
+};
+typedef globals_struct<> globals;
+
 // clang-format off
 
     // bit 0 (1) - set if: plain ASCII string character
     // bit 1 (2) - set if: whitespace
     // bit 4 (0x10) - set if: 0-9 e E .
-    constexpr static const uint8_t parse_flags[256] = {
+    template <typename unused>
+    const unsigned char globals_struct<unused>::parse_flags[256] = {
      // 0    1    2    3    4    5    6    7      8    9    A    B    C    D    E    F
         0,   0,   0,   0,   0,   0,   0,   0,     0,   2,   2,   0,   0,   2,   0,   0, // 0
         0,   0,   0,   0,   0,   0,   0,   0,     0,   0,   0,   0,   0,   0,   0,   0, // 1
@@ -162,15 +167,13 @@ struct globals_struct {
     };
 
 // clang-format on
-};
-typedef globals_struct<> globals;
 
-constexpr inline bool is_plain_string_character(char c) {
+inline bool is_plain_string_character(char c) {
     // return c >= 0x20 && c <= 0x7f && c != 0x22 && c != 0x5c;
     return (globals::parse_flags[static_cast<unsigned char>(c)] & 1) != 0;
 }
 
-constexpr inline bool is_whitespace(char c) {
+inline bool is_whitespace(char c) {
     // return c == '\r' || c == '\n' || c == '\t' || c == ' ';
     return (globals::parse_flags[static_cast<unsigned char>(c)] & 2) != 0;
 }
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<div class='path'>path: <a href='/guix/log/?id=3528d888eed2e226826085f68b40171dee18c5cb'>root</a>/<a href='/guix/log/.gitattributes?id=3528d888eed2e226826085f68b40171dee18c5cb'>.gitattributes</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/.gitattributes?id=3528d888eed2e226826085f68b40171dee18c5cb&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-10-14 00:24:34 +0200'>2021-10-14</span></td><td><a href='/guix/commit/.gitattributes?id=f8b10932c86cf4c1657a67e8c484d76f757b64bd'>Add git configuration templates to improve diff hunk header detection.</a><span class='msg-avail'>...</span></td><td>Sarah Morgensen</td></tr>