REPL: don't complete str and cmd macros when the input matches the internal name like r_ to r" (#56254)

(cherry picked from commit 4236a33)

Author: IanButterworth

stdlib/REPL/src/REPLCompletions.jl

@@ -140,6 +140,19 @@ function filtered_mod_names(ffunc::Function, mod::Module, name::AbstractString,
     all || filter!(Base.Fix1(Base.isexported, mod), ssyms)
     filter!(ffunc, ssyms)
     macros = filter(x -> startswith(String(x), "@" * name), ssyms)
+
+    # don't complete string and command macros when the input matches the internal name like `r_` to `r"`
+    if !startswith(name, "@")
+        filter!(macros) do m
+            s = String(m)
+            if endswith(s, "_str") || endswith(s, "_cmd")
+                occursin(name, first(s, length(s)-4))
+            else
+                true
+            end
+        end
+    end
+
     syms = String[sprint((io,s)->Base.show_sym(io, s; allow_macroname=true), s) for s in ssyms if completes_global(String(s), name)]
     appendmacro!(syms, macros, "_str", "\"")
     appendmacro!(syms, macros, "_cmd", "`")

stdlib/REPL/test/replcompletions.jl

@@ -1529,6 +1529,16 @@ test_dict_completion("test_repl_comp_customdict")
     @test "testcmd`" in c
     c, r, res = test_complete("CompletionFoo.tϵsτc")
     @test "tϵsτcmδ`" in c
+
+    # Issue #56071: don't complete string and command macros when the input matches the internal name like `r_` to `r"`
+    c, r, res = test_complete("CompletionFoo.teststr_")
+    @test isempty(c)
+    c, r, res = test_complete("CompletionFoo.teststr_s")
+    @test isempty(c)
+    c, r, res = test_complete("CompletionFoo.testcmd_")
+    @test isempty(c)
+    c, r, res = test_complete("CompletionFoo.testcmd_c")
+    @test isempty(c)
 end
 
 @testset "Keyword-argument completion" begin