From 0e00e8394485fa26b2e32ddc9a260cce8ebc041a Mon Sep 17 00:00:00 2001
From: Tom Poole <thomas.poole@roli.com>
Date: Fri, 28 Jun 2019 15:34:16 +0100
Subject: [PATCH] Removed some `extern "C"` declarations from libpng

---
 .../image_formats/juce_PNGLoader.cpp             |  4 ++--
 .../image_formats/pnglib/libpng_readme.txt       |  4 +++-
 modules/juce_graphics/image_formats/pnglib/png.h | 16 +++++++++-------
 .../juce_graphics/image_formats/pnglib/pngpriv.h | 16 +++++++++-------
 4 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/modules/juce_graphics/image_formats/juce_PNGLoader.cpp b/modules/juce_graphics/image_formats/juce_PNGLoader.cpp
index 66e4167f37..8afd94f287 100644
--- a/modules/juce_graphics/image_formats/juce_PNGLoader.cpp
+++ b/modules/juce_graphics/image_formats/juce_PNGLoader.cpp
@@ -271,8 +271,8 @@ namespace pnglibNamespace
   #define PNG_sCAL_PRECISION 5
   #define PNG_sRGB_PROFILE_CHECKS 2
 
-  #define PNG_LINKAGE_API inline
-  #define PNG_LINKAGE_FUNCTION inline
+  #define PNG_LINKAGE_API
+  #define PNG_LINKAGE_FUNCTION
 
   #define PNG_ARM_NEON_OPT 0
 
diff --git a/modules/juce_graphics/image_formats/pnglib/libpng_readme.txt b/modules/juce_graphics/image_formats/pnglib/libpng_readme.txt
index 75a4595a21..156a800828 100644
--- a/modules/juce_graphics/image_formats/pnglib/libpng_readme.txt
+++ b/modules/juce_graphics/image_formats/pnglib/libpng_readme.txt
@@ -1,2 +1,4 @@
-
 These files are from the libpng library - http://www.libpng.org/
+
+We have removed all `extern "C"` from the library to prevent symbol collision
+with projects that use their own version of libpng.
diff --git a/modules/juce_graphics/image_formats/pnglib/png.h b/modules/juce_graphics/image_formats/pnglib/png.h
index 139eb0dc0f..9fe598be30 100644
--- a/modules/juce_graphics/image_formats/pnglib/png.h
+++ b/modules/juce_graphics/image_formats/pnglib/png.h
@@ -363,10 +363,11 @@
 
 #ifndef PNG_VERSION_INFO_ONLY
 
-/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
+// JUCE modification
+///* Inhibit C++ name-mangling for libpng functions but not for system calls. */
+//#ifdef __cplusplus
+//extern "C" {
+//#endif /* __cplusplus */
 
 /* Version information for C files, stored in png.c.  This had better match
  * the version above.
@@ -3238,9 +3239,10 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
   PNG_EXPORT_LAST_ORDINAL(249);
 #endif
 
-#ifdef __cplusplus
-}
-#endif
+// JUCE modification
+//#ifdef __cplusplus
+//}
+//#endif
 
 #endif /* PNG_VERSION_INFO_ONLY */
 /* Do not put anything past this line */
diff --git a/modules/juce_graphics/image_formats/pnglib/pngpriv.h b/modules/juce_graphics/image_formats/pnglib/pngpriv.h
index 583c26f9bd..7d6605515c 100644
--- a/modules/juce_graphics/image_formats/pnglib/pngpriv.h
+++ b/modules/juce_graphics/image_formats/pnglib/pngpriv.h
@@ -958,10 +958,11 @@ PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);
 #endif /* SIMPLIFIED_READ/WRITE */
 
 
-/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
+// JUCE modification
+///* Inhibit C++ name-mangling for libpng functions but not for system calls. */
+//#ifdef __cplusplus
+//extern "C" {
+//#endif /* __cplusplus */
 
 /* Internal functions; these are not exported from a DLL however because they
  * are used within several of the C source files they have to be C extern.
@@ -2144,9 +2145,10 @@ PNG_INTERNAL_FUNCTION(int,
 
 #include "pngdebug.h"
 
-#ifdef __cplusplus
-}
-#endif
+// JUCE modification
+//#ifdef __cplusplus
+//}
+//#endif
 
 #endif /* PNG_VERSION_INFO_ONLY */
 #endif /* PNGPRIV_H */