Refactor some gprbuild bits out

Makefile

@@ -6,7 +6,7 @@ EXECUTABLE=build/pipeline
 
 all: $(EXECUTABLE)
 clean:
-	$(GPRCLEAN)
+	$(GPRCLEAN) -Ppipeline
 
 check: all build/c_pipeline
 	./t/bin/bats ./t/*.bats
@@ -14,7 +14,7 @@ check: all build/c_pipeline
 generated:  build/generated/nanomsg_nn_h.ads
 
 build/pipeline:  generated
-	$(GPRBUILD)
+	$(GPRBUILD) -Ppipeline
 
 build/c_pipeline: contrib/pipeline.c
 	$(CC) -lnanomsg -o build/c_pipeline contrib/pipeline.c

pipeline.gpr

@@ -1,13 +1,12 @@
+with "shared";
 
 project Pipeline is
-    for Source_Dirs use (".", "build/generated");
-    for Main use ("pipeline.adb");
-    for Object_Dir use "build";
-    for Exec_Dir use "build";
+   for Main use ("pipeline.adb");
 
-    package Compiler is
-    for Default_Switches("ada") use
-            ("-g", "-gnateS", "-ftest-coverage", "-gnatv", "-gnatf", "-gnatyabcefhiklmnprst", "-gnat12");
-    end Compiler;
+   for Source_Dirs use Shared'Source_Dirs;
+   for Object_Dir use Shared'Object_Dir;
+   for Exec_Dir use Shared'Exec_Dir;
+
+   package Compiler renames Shared.Compiler;
 end Pipeline;
 

shared.gpr

@@ -0,0 +1,13 @@
+abstract project Shared is
+   for Source_Files use (); --  no source files!
+   for Source_Dirs use (".", "build/generated");
+   for Object_Dir use "build";
+   for Exec_Dir use "build";
+
+   package Compiler is
+   for Default_Switches("ada") use
+           ("-g", "-gnateS", "-ftest-coverage",
+           "-gnatv", "-gnatf", "-gnatyabcefhiklmnprst",
+           "-gnat12");
+   end Compiler;
+end Shared;