Fixed GCC pre-8 build. (#1822) + added bonus the non-ASCII character pasted from GCC breaks my SourceTree/Git combo

imgui.cpp

@@ -705,7 +705,9 @@
 #pragma GCC diagnostic ignored "-Wconversion"               // warning: conversion to 'xxxx' from 'xxxx' may alter its value
 #pragma GCC diagnostic ignored "-Wformat-nonliteral"        // warning: format not a string literal, format string not checked
 #pragma GCC diagnostic ignored "-Wstrict-overflow"          // warning: assuming signed overflow does not occur when assuming that (X - c) > X is always false
-#pragma GCC diagnostic ignored "-Wclass-memaccess"          // warning: ‘memset/memcpy’ clearing/writing an object of type ‘xxxx’ with no trivial copy-assignment; use assignment or value-initialization instead
+#if __GNUC__ >= 8
+#pragma GCC diagnostic ignored "-Wclass-memaccess"          // warning: 'memset/memcpy' clearing/writing an object of type 'xxxx' with no trivial copy-assignment; use assignment or value-initialization instead
+#endif
 #endif
 
 // Enforce cdecl calling convention for functions called by the standard library, in case compilation settings changed the default to e.g. __vectorcall

imgui_draw.cpp

@@ -54,7 +54,9 @@
 #pragma GCC diagnostic ignored "-Wunused-function"          // warning: 'xxxx' defined but not used
 #pragma GCC diagnostic ignored "-Wdouble-promotion"         // warning: implicit conversion from 'float' to 'double' when passing argument to function
 #pragma GCC diagnostic ignored "-Wconversion"               // warning: conversion to 'xxxx' from 'xxxx' may alter its value
-#pragma GCC diagnostic ignored "-Wclass-memaccess"          // warning: ‘memset/memcpy’ clearing/writing an object of type ‘xxxx’ with no trivial copy-assignment; use assignment or value-initialization instead
+#if __GNUC__ >= 8
+#pragma GCC diagnostic ignored "-Wclass-memaccess"          // warning: 'memset/memcpy' clearing/writing an object of type 'xxxx' with no trivial copy-assignment; use assignment or value-initialization instead
+#endif
 #endif
 
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