When given - as the program name, read program from stdin (JuliaLang#…

…43191)

NEWS.md

@@ -60,6 +60,7 @@ Command-line option changes
 * New option `--strip-ir` to remove the compiler's IR (intermediate representation) of source
   code when building a system image. The resulting image will only work if `--compile=all` is
   used, or if all needed code is precompiled ([#42925]).
+* When the program file is `-` the code to be executed is read from standard in ([#43191]).
 
 Multi-threading changes
 -----------------------

base/client.jl

@@ -301,7 +301,11 @@ function exec_options(opts)
             exit_on_sigint(true)
         end
         try
-            include(Main, PROGRAM_FILE)
+            if PROGRAM_FILE == "-"
+                include_string(Main, read(stdin, String), "stdin")
+            else
+                include(Main, PROGRAM_FILE)
+            end
         catch
             invokelatest(display_error, scrub_repl_backtrace(current_exceptions()))
             if !is_interactive::Bool

test/cmdlineargs.jl

@@ -762,3 +762,22 @@ end
 
 # issue #39259, shadowing `ARGS`
 @test success(`$(Base.julia_cmd()) --startup-file=no -e 'ARGS=1'`)
+
+@testset "- as program file reads from stdin" begin
+    for args in (`- foo bar`, `-- - foo bar`)
+        cmd = `$(Base.julia_cmd()) --startup-file=no $(args)`
+        io = IOBuffer()
+        open(cmd, io; write=true) do proc
+            write(proc, """
+                println(PROGRAM_FILE)
+                println(@__FILE__)
+                foreach(println, ARGS)
+            """)
+        end
+        lines = collect(eachline(seekstart(io)))
+        @test lines[1] == "-"
+        @test lines[2] == "stdin"
+        @test lines[3] == "foo"
+        @test lines[4] == "bar"
+    end
+end