docs: Add Environment variables for compiler/linker selection

We really should be documenting these in an easy to find and reference
place.

docs/markdown/Reference-tables.md

@@ -255,3 +255,22 @@ These are the values that can be passed to `dependency` function's
 | config-tool       | Use a custom dep tool such as `cups-config`  |
 | system            | System provided (e.g. OpenGL)                |
 | extraframework    | A macOS/iOS framework                        |
+
+
+## Compiler and Linker selection variables
+
+| Language      | Compiler | Linker    | Note                                        |
+|:-------------:|----------|-----------|---------------------------------------------|
+| C             | CC       | CC_LD     |                                             |
+| C++           | CXX      | CXX_LD    |                                             |
+| D             | DC       | DC_LD     | Before 0.54 D_LD*                           |
+| Fortran       | FC       | FC_LD     | Before 0.54 F_LD*                           |
+| Objective-C   | OBJC     | OBJC_LD   |                                             |
+| Objective-C++ | OBJCXX   | OBJCXX_LD | Before 0.54 OBJCPP_LD*                      |
+| Rust          | RUSTC    | RUSTC_LD  | Before 0.54 RUST_LD*                        |
+| Vala          | VALAC    |           | Use CC_LD. Vala transpiles to C             |
+| C#            | CSC      | CSC       | The linker is the compiler                  |
+
+*The old environment variales are still supported, but are deprecated and will
+be removed in a future version of meson.
+

test cases/java/1 basic/meson.build

@@ -5,3 +5,7 @@ javaprog = jar('myprog', 'com/mesonbuild/Simple.java',
   install : true,
   install_dir : get_option('bindir'))
 test('mytest', javaprog)
+
+jc = meson.get_compiler('java')
+message(jc.get_id())
+message(jc.get_linker_id())