Select dynamic library if SO version is set

This prevents any inconsistency on the command line between ALOG_VERSION
(or its default value) and LIBRARY_KIND (or its default value).

Require an explicit ALOG_VERSION in gprbuild command line.  The default
was dynamic in Makefile and static in projects, leading to some
confusion. For example, debian/rules was setting VERSION for tests.

Split build_lib_[dynamic|static] Makefile targets as done for install.

Rename the project version internal variable after the external one,
and move it from common project to the only project it affects.

Makefile

@@ -59,12 +59,14 @@ all: build_lib
 tests: build_tests
 	@$(OBJECTDIR)/test_runner
 
-build_lib:
-	@gprbuild $(GMAKE_OPTS) -Palog -XALOG_VERSION="$(VERSION)" \
-		-XLIBRARY_KIND="$(LIBRARY_KIND)"
+build_lib: build_lib_$(LIBRARY_KIND)
+build_lib_dynamic:
+	@gprbuild $(GMAKE_OPTS) -Palog -XALOG_VERSION="$(VERSION)"
+build_lib_static:
+	@gprbuild $(GMAKE_OPTS) -Palog -XALOG_VERSION=
 
 build_tests:
-	@gprbuild $(GMAKE_OPTS) -Palog_tests -XALOG_BUILD="tests"
+	@gprbuild $(GMAKE_OPTS) -Palog_tests -XALOG_BUILD="tests" -XALOG_VERSION=
 
 build_all: build_lib build_tests
 
@@ -104,7 +106,7 @@ install_tests: build_tests
 cov:
 	@mkdir -p $(COVDIR)
 	@rm -f $(OBJECTDIR)/cov/*.gcda
-	@gprbuild $(GMAKE_OPTS) -Palog_tests -XALOG_BUILD="coverage"
+	@gprbuild $(GMAKE_OPTS) -Palog_tests -XALOG_BUILD="coverage" -XALOG_VERSION=
 	@$(OBJECTDIR)/cov/test_runner || true
 	@lcov -c -d $(OBJECTDIR)/cov/ -o $(OBJECTDIR)/cov/alog_tmp.info
 	@lcov -e $(OBJECTDIR)/cov/alog_tmp.info "$(PWD)/src/*.adb" \
@@ -113,7 +115,7 @@ cov:
 
 prof:
 	@rm -f $(OBJECTDIR)/callgrind.*
-	gprbuild $(GMAKE_OPTS) -Palog_tests -XALOG_BUILD="profiling"
+	gprbuild $(GMAKE_OPTS) -Palog_tests -XALOG_BUILD="profiling" -XALOG_VERSION=
 	valgrind -q --tool=callgrind \
 		--callgrind-out-file=$(OBJECTDIR)/callgrind.out.%p $(OBJECTDIR)/profiler
 	callgrind_annotate $(OBJECTDIR)/callgrind.* > $(OBJECTDIR)/profile.txt

alog.gpr

@@ -24,21 +24,26 @@ with "alog_common";
 
 library project Alog is
 
+   Alog_Version := External ("ALOG_VERSION");
+   --  Require an explicit setting for ALOG_VERSION.
+   --  Build a static library when it is empty,
+   --  else a relocatable library with the given shared object version.
+
    for Languages use Alog_Common.Languages;
    for Source_Dirs use ("src");
-   for Object_Dir use "obj/lib/" & Alog_Common.Libtype;
    for Library_Name use "alog";
-   for Library_Dir use "lib/" & Alog_Common.Libtype;
-   for Library_Kind use Alog_Common.Libtype;
 
-   case Alog_Common.Libtype is
-      when "static" =>
-         null;
-      when "dynamic" =>
-         for Library_Version use "libalog.so." & Alog_Common.Version;
+   case Alog_Version is
+      when "" =>
+         for Library_Kind use "static";
+      when others =>
+         for Library_Kind use "dynamic";
+         for Library_Version use "libalog.so." & Alog_Version;
          --  Start with LDFLAGS as it may contain options like --as-needed.
          for Leading_Library_Options use Alog_Common.Ldflags;
    end case;
+   for Object_Dir use "obj/lib/" & project'Library_Kind;
+   for Library_Dir use "lib/" & project'Library_Kind;
 
    package Compiler extends Alog_Common.Compiler is
       for Default_Switches ("Ada") use

alog_common.gpr

@@ -24,11 +24,6 @@ abstract project Alog_Common is
 
    for Source_Dirs use ();
 
-   Version := external ("ALOG_VERSION", "0.1");
-
-   type Lib_Type is ("static", "dynamic");
-   Libtype : Lib_Type := external ("LIBRARY_KIND", "static");
-
    Adaflags := External_As_List ("ADAFLAGS", " ");
    Cflags := External_As_List ("CFLAGS", " ");
    Cppflags := External_As_List ("CPPFLAGS", " ");

examples/Makefile

@@ -24,7 +24,7 @@ all: build_examples
 
 # C compilations may happen if the library is updated.
 build_examples:
-	@gprbuild -p -Palog_examples \
+	@gprbuild -p -Palog_examples -XALOG_VERSION= \
 	  $(foreach v,ADAFLAGS CFLAGS CPPFLAGS LDFLAGS,"-X$(v)=$($(v))")
 
 clean: