fix #2101

CMakeLists.txt

@@ -114,22 +114,22 @@ if (STATIC)
     set(LIBRARY_TYPE)
 endif()
 
+# Compiler specific environments
 if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   set(CLANG 1)
 endif()
-
-if (WIN32)
-    if (MSVC)
-        add_definitions(-D_CRT_SECURE_NO_WARNINGS)
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /utf-8")
-        if (NOT CLANG)
-            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /MP")
-        endif()
+if(CMAKE_COMPILER_IS_GNUCXX OR MINGW)
+    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -Wall -DDEBUG -pedantic -Og")
+elseif(MSVC)
+    add_definitions(-D_CRT_SECURE_NO_WARNINGS)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /utf-8")
+    if (NOT CLANG)
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /MP")
     endif()
-    if(CLANG)
-        set(CMAKE_CXX_FLAGS_RELEASE  "${CMAKE_CXX_FLAGS_RELEASE} -Wno-unused-command-line-argument")
-    endif()
-    set(LIB_Ws2_32 Ws2_32)
+    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} /Wall /bigobj")
+elseif(CLANG)
+    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -Wno-unused-command-line-argument")
+    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -Wall -DDEBUG -pedantic -O0")
 endif()
 
 if (OPENMP_BUILD)
@@ -140,14 +140,15 @@ if (OPENMP_BUILD)
     endif()
 endif()
 
+
 if (CYGWIN)
     add_definitions(-D__CYGWIN__)
-endif()
-
-if (UNIX)
+elseif(UNIX)
     if (NOT ANDROID)
         set(LIB_pthread pthread)
     endif()
+elseif(WIN32)
+    set(LIB_Ws2_32 Ws2_32)
 endif()
 
 ###############################################################################

configure.ac

@@ -10,7 +10,11 @@ AC_INIT([tesseract],
         [m4_esyscmd_s([test -d .git && git describe --abbrev=4 || cat VERSION])],
         [https://github.com/tesseract-ocr/tesseract/issues],,
         [https://github.com/tesseract-ocr/tesseract/])
+
+# Store command like options for CXXFLAGS
+OLD_CXXFLAGS=$CXXFLAGS
 AC_PROG_CXX([g++ clang++])
+# reset compiler flags to initial flags
 AC_LANG([C++])
 AC_LANG_COMPILER_REQUIRE
 CXXFLAGS=${CXXFLAGS:-""}
@@ -284,17 +288,39 @@ AC_ARG_ENABLE([tessdata-prefix],
 AC_MSG_RESULT([$tessdata_prefix])
 AM_CONDITIONAL([NO_TESSDATA_PREFIX], [test "$tessdata_prefix" = "no"])
 
+
+# Detect Clang compiler
+AC_MSG_CHECKING([if compiling with clang])
+AC_COMPILE_IFELSE(
+[AC_LANG_PROGRAM([], [[
+#ifndef __clang__
+       not clang
+#endif
+]])],
+[CLANG=yes], [CLANG=no])
+AC_MSG_RESULT([$CLANG])
+
 # Check whether to enable debugging
 AC_MSG_CHECKING([whether to enable debugging])
 AC_ARG_ENABLE([debug],
   AS_HELP_STRING([--enable-debug], [turn on debugging [default=no]]))
 AC_MSG_RESULT([$enable_debug])
 if test x"$enable_debug" = x"yes"; then
-    AM_CXXFLAGS="$AM_CXXFLAGS -g -Wall -O0 -DDEBUG"
-    AM_CPPFLAGS="$AM_CPPFLAGS -g -Wall -DDEBUG"
+    CXXFLAGS=${CXXFLAGS:-"-O2"}
+    AM_CPPFLAGS="$AM_CPPFLAGS -g -Wall -DDEBUG -pedantic"
+    AM_CXXFLAGS="$AM_CXXFLAGS -g -Wall -DDEBUG -pedantic"
+    if test "x$CLANG" = "xyes"; then
+        # https://clang.llvm.org/docs/CommandGuide/clang.html
+        # clang treats -Og as -O1
+        AM_CPPFLAGS="$AM_CPPFLAGS -O0"
+        AM_CXXFLAGS="$AM_CXXFLAGS -O0"
+    else
+        AM_CPPFLAGS="$AM_CPPFLAGS -Og"
+        AM_CXXFLAGS="$AM_CXXFLAGS -Og"
+    fi
 else
     AM_CXXFLAGS="$AM_CXXFLAGS -O2 -DNDEBUG"
-    AM_CPPFLAGS="$AM_CPPFLAGS -DNDEBUG"
+    AM_CPPFLAGS="$AM_CPPFLAGS -O2 -DNDEBUG"
 fi
 
 #localedir='${prefix}/share/locale'
@@ -326,18 +352,6 @@ LT_INIT
 # ----------------------------------------
 # C++ related options
 # ----------------------------------------
-
-AC_MSG_CHECKING([if compiling with clang])
-AC_COMPILE_IFELSE(
-[AC_LANG_PROGRAM([], [[
-#ifndef __clang__
-       not clang
-#endif
-]])],
-[CLANG=yes], [CLANG=no])
-
-AC_MSG_RESULT([$CLANG])
-
 dnl **********************
 dnl Turn on C++11 or newer
 dnl **********************