doxygen, gromacs, gromacs-plumed, spice-server: error: expected identifier or '('

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I was trying to install QEMU under Mac OS X 10.6.8 on my OG white polycarbonate MacBook1,1 32-bit-ONLY DualCore "Yonah" CPU. One of the dependancies for QEMU is spice-server, but the build failed, apparently due to a syntax error. Please see attached log.

[leeeoooooo]

spice-server build log

[ryandesign (Ryan Carsten Schmidt)]

Something has gone rather wrong when the error is occurring in a compiler header...

:info:build In file included from lines.c:56:
:info:build /opt/local/include/libcxx/v1/math.h:316:8: error: expected identifier or '('
:info:build extern "C" {
:info:build        ^

[jmroot (Joshua Root)]

It's somehow including a C++ header from C code.

[ryandesign (Ryan Carsten Schmidt)]

/opt/local/include/libcxx/v1/math.h is provided by the macports-libcxx port. math.h is supposed to be a C header. The port also helpfully installs a math.h.orig file that helps us see that originally math.h didn't contain the problematic line—which is extern "C" {, since that line can only be used in C++ code.

The macports-libcxx port copies its files from the clang-11 port. The problematic changes are added to the math.h header by this patch:

source:macports-ports/lang/llvm-11/files/3001-Fix-missing-long-long-math-prototypes-when-using-the.patch​

The problematic code only takes effect on Mac OS X versions earlier than 10.7.

The problematic patch is also in the clang-10 and clang-9.0 ports.

Is this the fix?

math.h

@@ -313 +313 @@
 
 # if __APPLE_BAD_MATH_H
 /* These prototypes are incorrectly omitted from <math.h> on Snow Leopard despite being available */
+#  ifdef __cplusplus
 extern "C" {
+#  endif
     extern long long int llrintl(long double);
     extern long long int llrint(double);
     extern long long int llrintf(float);
@@ -321 +323 @@
     extern long long int llroundl(long double);
     extern long long int llround(double);
     extern long long int llroundf(float);
+#  ifdef __cplusplus
 }
+#  endif
 # endif
 #endif // __APPLE__
 

[kencu (Ken)]

well, that is weird.

This never has come up since Jeremy wrote this patch up.

Is spice-server using the c++ compiler to compile “c” code?

[ryandesign (Ryan Carsten Schmidt)]

Replying to kencu:

Is spice-server using the c++ compiler to compile “c” code?

If it were, the problem wouldn't occur, since extern "C" is valid in C++.

[ryandesign (Ryan Carsten Schmidt)]

This problem causes doxygen to fail to build on 10.6 which causes the hundreds of ports that depend on doxygen to fail to build.

​https://build.macports.org/builders/ports-10.6_x86_64-builder/builds/222805

​https://build.macports.org/builders/ports-10.6_i386-builder/builds/187050

It also affects gromacs and gromacs-plumed (#67363).

[bazilio-ua]

HI!

Then maybe the person who maintains this port can add the fix from comment 4 to the macports-libcxx port patch? lots of ports on 10.6 are broken that depends on doxygen

​https://trac.macports.org/browser/macports-ports/lang/llvm-11/files/3001-Fix-missing-long-long-math-prototypes-when-using-the.patch

[aeiouaeiouaeiouaeiouaeiouaeiou]

In b9c20ba7e62bafad3aced00d9ef78dbe36aee07b/macports-ports (master):

imlib2: install docs by default only on macOS >=10.7

See: #69159

[Randrianasulu (Andrew Randrianasulu)]

Also affects openexr port on 10.6.8/x86-64, see

​https://build.macports.org/builders/ports-10.6_x86_64-builder/builds/277279/steps/install-port/logs/stdio