scons: Unify the flags shared by gcc and clang

This patch restructures and unifies the flags used by gcc and clang as
they are largely the same. The common parts are now dealt with in a
shared block of code, and the few bits and pieces that are
specifically affecting either gcc or clang are done separately.

1 files changed, 42 insertions, 17 deletions

diff --git a/SConstruct b/SConstruct
index 0540ba80f..4ca4ae56d 100755
--- a/SConstruct
+++ b/SConstruct
@@ -515,6 +515,38 @@ if main['GCC'] + main['CLANG'] > 1:
     Exit(1)
 
 # Set up default C++ compiler flags
+if main['GCC'] or main['CLANG']:
+    # As gcc and clang share many flags, do the common parts here
+    main.Append(CCFLAGS=['-pipe'])
+    main.Append(CCFLAGS=['-fno-strict-aliasing'])
+    # Enable -Wall and then disable the few warnings that we
+    # consistently violate
+    main.Append(CCFLAGS=['-Wall', '-Wno-sign-compare', '-Wundef'])
+    # We always compile using C++11, but only gcc >= 4.7 and clang 3.1
+    # actually use that name, so we stick with c++0x
+    main.Append(CXXFLAGS=['-std=c++0x'])
+    # Add selected sanity checks from -Wextra
+    main.Append(CXXFLAGS=['-Wmissing-field-initializers',
+                          '-Woverloaded-virtual'])
+else:
+    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
+    print "Don't know what compiler options to use for your compiler."
+    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
+    print termcap.Yellow + '       version:' + termcap.Normal,
+    if not CXX_version:
+        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
+               termcap.Normal
+    else:
+        print CXX_version.replace('\n', '<nl>')
+    print "       If you're trying to use a compiler other than GCC"
+    print "       or clang, there appears to be something wrong with your"
+    print "       environment."
+    print "       "
+    print "       If you are trying to use a compiler other than those listed"
+    print "       above you will need to ease fix SConstruct and "
+    print "       src/SConscript to support that compiler."
+    Exit(1)
+
 if main['GCC']:
     # Check for a supported version of gcc, >= 4.4 is needed for c++0x
     # support. See http://gcc.gnu.org/projects/cxx0x.html for details
@@ -525,12 +557,6 @@ if main['GCC']:
         Exit(1)
 
     main['GCC_VERSION'] = gcc_version
-    main.Append(CCFLAGS=['-pipe'])
-    main.Append(CCFLAGS=['-fno-strict-aliasing'])
-    main.Append(CCFLAGS=['-Wall', '-Wno-sign-compare', '-Wundef'])
-    main.Append(CXXFLAGS=['-Wmissing-field-initializers',
-                          '-Woverloaded-virtual'])
-    main.Append(CXXFLAGS=['-std=c++0x'])
 
     # Check for versions with bugs
     if not compareVersions(gcc_version, '4.4.1') or \
@@ -571,17 +597,16 @@ elif main['CLANG']:
         print 'Error: Unable to determine clang version.'
         Exit(1)
 
-    main.Append(CCFLAGS=['-pipe'])
-    main.Append(CCFLAGS=['-fno-strict-aliasing'])
-    main.Append(CCFLAGS=['-Wall', '-Wno-sign-compare', '-Wundef'])
-    main.Append(CCFLAGS=['-Wno-tautological-compare'])
-    main.Append(CCFLAGS=['-Wno-self-assign'])
-    # Ruby makes frequent use of extraneous parantheses in the printing
-    # of if-statements
-    main.Append(CCFLAGS=['-Wno-parentheses'])
-    main.Append(CXXFLAGS=['-Wmissing-field-initializers',
-                          '-Woverloaded-virtual'])
-    main.Append(CXXFLAGS=['-std=c++0x'])
+    # clang has a few additional warnings that we disable,
+    # tautological comparisons are allowed due to unsigned integers
+    # being compared to constants that happen to be 0, and extraneous
+    # parantheses are allowed due to Ruby's printing of the AST,
+    # finally self assignments are allowed as the generated CPU code
+    # is relying on this
+    main.Append(CCFLAGS=['-Wno-tautological-compare',
+                         '-Wno-parentheses',
+                         '-Wno-self-assign'])
+
     # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
     # opposed to libstdc++ to make the transition from TR1 to
     # C++11. See http://libcxx.llvm.org. However, clang has chosen a