gcc7, gcc7Stdenv, gfortran7: remove old implementation

pkgs/by-name/bl/blackmagic-desktop-video/package.nix

@@ -6,7 +6,7 @@
 , autoPatchelfHook
 , libcxx
 , libGL
-, gcc7
+, gcc
 }:
 stdenv.mkDerivation (finalAttrs: {
   pname = "blackmagic-desktop-video";
@@ -16,7 +16,7 @@ stdenv.mkDerivation (finalAttrs: {
     autoPatchelfHook
     libcxx
     libGL
-    gcc7.cc.lib
+    gcc.cc.lib
   ];
 
   # yes, the below download function is an absolute mess.

pkgs/development/compilers/gcc/all.nix

@@ -26,7 +26,7 @@ let
         threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else { };
         isl = if       stdenv.isDarwin then null
               else if    atLeast "9"   then isl_0_20
-              else    /* atLeast "7" */     isl_0_17;
+              else    /* atLeast "8" */     isl_0_17;
       } // lib.optionalAttrs (!(atLeast "9")) {
         # gcc 10 is too strict to cross compile gcc <= 8
         stdenv = if (stdenv.targetPlatform != stdenv.buildPlatform) && stdenv.cc.isGNU then gcc9Stdenv else stdenv;

pkgs/development/compilers/gcc/default.nix

@@ -75,7 +75,6 @@ let
   is10 = majorVersion == "10";
   is9  = majorVersion == "9";
   is8  = majorVersion == "8";
-  is7  = majorVersion == "7";
 
     disableBootstrap = atLeast11 && !stdenv.hostPlatform.isDarwin && (atLeast12 -> !profiledCompiler);
 
@@ -164,7 +163,7 @@ assert stdenv.buildPlatform.isDarwin -> gnused != null;
 
 # The go frontend is written in c++
 assert langGo -> langCC;
-assert (!is7 && !is8) -> (langAda -> gnat-bootstrap != null);
+assert (!is8) -> (langAda -> gnat-bootstrap != null);
 
 # TODO: fixup D bootstapping, probably by using gdc11 (and maybe other changes).
 #   error: GDC is required to build d
@@ -258,9 +257,7 @@ pipe ((callFile ./common/builder.nix {}) ({
 
   configurePlatforms = [ "build" "host" "target" ];
 
-  configureFlags = (callFile ./common/configure-flags.nix { })
-    ++ optional (is7 && targetPlatform.isAarch64) "--enable-fix-cortex-a53-843419"
-    ++ optional (is7 && targetPlatform.isNetBSD) "--disable-libcilkrts";
+  configureFlags = (callFile ./common/configure-flags.nix { });
 
   inherit targetConfig;
 
@@ -316,11 +313,7 @@ pipe ((callFile ./common/builder.nix {}) ({
       EXTRA_FLAGS_FOR_TARGET
       EXTRA_LDFLAGS_FOR_TARGET
       ;
-  } // optionalAttrs is7 {
-    NIX_CFLAGS_COMPILE = optionalString (stdenv.cc.isClang && langFortran) "-Wno-unused-command-line-argument"
-      # Downgrade register storage class specifier errors to warnings when building a cross compiler from a clang stdenv.
-      + optionalString (stdenv.cc.isClang && targetPlatform != hostPlatform) " -Wno-register";
-  } // optionalAttrs (!is7 && !atLeast12 && stdenv.cc.isClang && targetPlatform != hostPlatform) {
+  } // optionalAttrs (!atLeast12 && stdenv.cc.isClang && targetPlatform != hostPlatform) {
     NIX_CFLAGS_COMPILE = "-Wno-register";
   });