abacus: fix include directories

This cleans up one of my major pain points with the Meson way of doing
things.

The Meson solution to have nice includes would have been to create an
`include/<name>` directory per library I create...

CMakeLists.txt

@@ -10,6 +10,9 @@ target_compile_options(common_options INTERFACE
   -Wall
   -Wextra
 )
+target_include_directories(common_options INTERFACE
+  src
+)
 
 add_subdirectory(src)
 add_subdirectory(tests)

src/abacus.cc

@@ -1,4 +1,4 @@
-#include "parser-driver.hh" // FIXME: I would like `parse/parser-driver.hh` path instead...
+#include "parse/parser-driver.hh"
 
 int main() {
     abacus::parse::ParserDriver driver{};

src/bignum/CMakeLists.txt

@@ -3,7 +3,3 @@ add_library(bignum STATIC
   bignum.hh
 )
 target_link_libraries(bignum PRIVATE common_options)
-
-target_include_directories(bignum PUBLIC
-  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
-)

src/parse/CMakeLists.txt

@@ -18,6 +18,6 @@ target_link_libraries(parse PRIVATE
 )
 
 target_include_directories(parse PUBLIC
-  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
   $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
 )

src/parse/parser-driver.hh

@@ -4,7 +4,7 @@
 
 #include "parser.hh"
 
-#include "bignum.hh" // FIXME: I would like `bignum/bignum.hh` path instead...
+#include "bignum/bignum.hh"
 
 namespace abacus::parse {
 

src/parse/parser.yy

@@ -36,7 +36,7 @@ namespace abacus::parse {
 class ParserDriver;
 } // namespace abacus::parse
 
-#include "bignum.hh" // FIXME: I would like `bignum/bignum.hh` path instead...
+#include "bignum/bignum.hh"
 }
 
 %code provides {

tests/unit/bignum.cc

@@ -2,7 +2,7 @@
 
 #include <gtest/gtest.h>
 
-#include "bignum.hh"
+#include "bignum/bignum.hh"
 
 using namespace abacus::bignum;