Add linker flag and LLD support.

Author: tritao

src/_premake_init.lua

@@ -892,6 +892,16 @@
 		}
 	}
 
+	api.register {
+		name = "linker",
+		scope = "config",
+		kind = "string",
+		allowed = {
+			"Default",
+			"LLD",
+		}
+	}
+
 	api.register {
 		name = "locale",
 		scope = "config",

src/tools/clang.lua

@@ -253,6 +253,7 @@
 				if cfg.system == p.WINDOWS then return "-mwindows" end
 			end,
 		},
+		linker = gcc.ldflags.linker,
 		sanitize = {
 			Address = "-fsanitize=address",
 		},

src/tools/gcc.lua

@@ -478,6 +478,10 @@
 				if cfg.system == p.WINDOWS then return "-mwindows" end
 			end,
 		},
+		linker = {
+			Default = "",
+			LLD = "-fuse-ld=lld"
+		},
 		sanitize = {
 			Address = "-fsanitize=address",
 		},

tests/tools/test_clang.lua

@@ -106,6 +106,16 @@
 		test.excludes("-fopenmp", clang.getcflags(cfg))
 	end
 
+--
+-- Check handling of linker flag.
+--
+
+function suite.ldflags_linker_lld()
+	linker "LLD"
+	prepare()
+	test.contains("-fuse-ld=lld", clang.getldflags(cfg))
+end
+
 --
 -- Check the translation of CXXFLAGS.
 --

tests/tools/test_gcc.lua

@@ -811,6 +811,17 @@
 	end
 
 
+--
+-- Check handling of linker flag.
+--
+
+function suite.ldflags_linker_lld()
+	linker "LLD"
+	prepare()
+	test.contains("-fuse-ld=lld", gcc.getldflags(cfg))
+end
+
+
 --
 -- Check handling of link time optimization flag.
 --

website/docs/Linking.md

@@ -40,3 +40,7 @@ If you need to discover the location of a library, use the [`os.findlib`](os.fin
 ```lua
 libdirs { os.findlib("X11") }
 ```
+
+### Linker
+
+The linker defaults to the specified toolset default linker, but can be changed with the [`linker`](linker.md) flag.

website/docs/linker.md

@@ -0,0 +1,28 @@
+Specifies the linker.
+
+```lua
+linker("value")
+```
+
+### Parameters ###
+
+`value` is a string value.
+
+By default, `Default` and `LLD` are allowed, but toolsets or modules canprovide support for other linkers.
+
+### Applies To ###
+
+Project configurations.
+
+### Availability ###
+
+Premake 5.0 beta 3 or later.
+
+### Examples ###
+
+Sets `LLD` as the linker.
+
+```lua
+filter { "toolset:clang" }
+   linker { "LLD" }
+```

website/sidebars.js

@@ -199,6 +199,7 @@ module.exports = {
 						'largeaddressaware',
 						'libdirs',
 						'linkbuildoutputs',
+						'linker',
 						'linkgroups',
 						'linkoptions',
 						'links',