From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Sun, 22 May 2022 00:27:12 +0000 (-0700)
Subject: cgraph: add an abstraction for squashing unused symbol warnings
X-Git-Tag: 5.0.0~15^2~1
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e391f114f6dec532acc637a0484d72642bbffbd0;p=graphviz

cgraph: add an abstraction for squashing unused symbol warnings
---

diff --git a/lib/cgraph/CMakeLists.txt b/lib/cgraph/CMakeLists.txt
index 1b12c4b18..ab983da8b 100644
--- a/lib/cgraph/CMakeLists.txt
+++ b/lib/cgraph/CMakeLists.txt
@@ -23,6 +23,7 @@ add_library(cgraph SHARED
   stack.h
   strcasecmp.h
   unreachable.h
+  unused.h
 
   # Source files
   agerror.c
diff --git a/lib/cgraph/Makefile.am b/lib/cgraph/Makefile.am
index c1265354c..31b608e8a 100644
--- a/lib/cgraph/Makefile.am
+++ b/lib/cgraph/Makefile.am
@@ -10,7 +10,7 @@ endif
 
 pkginclude_HEADERS = cgraph.h
 noinst_HEADERS = agxbuf.h alloc.h bitarray.h cghdr.h exit.h itos.h likely.h \
-	prisize_t.h stack.h strcasecmp.h unreachable.h
+	prisize_t.h stack.h strcasecmp.h unreachable.h unused.h
 noinst_LTLIBRARIES = libcgraph_C.la
 lib_LTLIBRARIES = libcgraph.la
 pkgconfig_DATA = libcgraph.pc
diff --git a/lib/cgraph/cgraph.vcxproj b/lib/cgraph/cgraph.vcxproj
index 8431b5926..b31228eac 100644
--- a/lib/cgraph/cgraph.vcxproj
+++ b/lib/cgraph/cgraph.vcxproj
@@ -109,6 +109,7 @@ win_flex -oscan.c scan.l</Command>
     <ClInclude Include="stack.h" />
     <ClInclude Include="strcasecmp.h" />
     <ClInclude Include="unreachable.h" />
+    <ClInclude Include="unused.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="agerror.c" />
diff --git a/lib/cgraph/cgraph.vcxproj.filters b/lib/cgraph/cgraph.vcxproj.filters
index 84c8c2aa1..3238e92f3 100644
--- a/lib/cgraph/cgraph.vcxproj.filters
+++ b/lib/cgraph/cgraph.vcxproj.filters
@@ -51,6 +51,9 @@
     <ClInclude Include="unreachable.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="unused.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="agerror.c">
diff --git a/lib/cgraph/unused.h b/lib/cgraph/unused.h
new file mode 100644
index 000000000..0b29a08f4
--- /dev/null
+++ b/lib/cgraph/unused.h
@@ -0,0 +1,26 @@
+/// \file
+/// \brief abstraction for squashing compiler warnings for unused symbols
+
+#pragma once
+
+/// squash an unused variable/function warning in C
+///
+/// e.g.
+///
+///   static UNUSED void my_uncalled_function(void) { }
+///   static UNUSED int my_unused_variable;
+///
+/// Use this sparingly, as the MSVC version applies to everything in both the
+/// current and next line, so can end up accidentally masking genuine problems.
+/// Only use this in C code. In C++, use `[[maybe_unused]]`.
+#ifdef __GNUC__ // Clang and GCC
+#define UNUSED __attribute__((unused))
+#elif defined(_MSC_VER) // MSVC
+#define UNUSED                                                                 \
+  __pragma(warning(suppress : 4100 /* unreferenced formal parameter */         \
+                   4101            /* unreferenced local variable */           \
+                   4505            /* unreferenced local function */           \
+                   ))
+#else
+#define UNUSED /* nothing */
+#endif