Add configure.exe-like FOO_LIBS=bar style command line options

Add the command line options supported by the windows version of
configure and respect them when running our configure tests.

Done-with: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Change-Id: I1206d60a177e251540d34d232c73c930847564b3
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

config_help.txt

@@ -1,4 +1,8 @@
-Usage:  configure [options]
+Usage:  configure [options] [assignments]
+
+Configure understands variable assignments like VAR=value on the command line.
+These override any values possibly obtained from pkg-config. The variables
+are mentioned in the descriptions of the options they relate to.
 
 Top-level installation directories:
   -prefix <dir> ...... The deployment directory, as seen on the target device.
@@ -161,6 +165,7 @@ Component selection:
   -no-dbus ............. Do not build the Qt D-Bus module [default on Android]
   -dbus-linked ......... Build Qt D-Bus and link to libdbus-1 [auto]
   -dbus-runtime ........ Build Qt D-Bus and dynamically load libdbus-1 [no]
+                         DBUS_PATH= DBUS_HOST_PATH=
   -feature-<feature> ... Enable <feature>. The available features are described
                          in src/corelib/global/qfeatures.txt. [all enabled]
   -accessibility ....... Enable accessibility support [yes]
@@ -182,6 +187,7 @@ Core options:
   -pps ................. Enable PPS support [auto] (QNX only)
   -pcre ................ Select used libpcre3 [system/qt]
   -zlib ................ Select used zlib [system/qt]
+                         ZLIB_LIBS=
 
   Logging backends:
     -journald .......... Enable journald support [no]
@@ -194,6 +200,7 @@ Network options:
   -no-openssl .......... Do not use OpenSSL [default on Apple]
   -openssl-linked ...... Use OpenSSL and link to libssl [no]
   -openssl-runtime ..... Use OpenSSL and dynamically load libssl [auto]
+                         OPENSSL_PATH= OPENSSL_LIBS=
   -securetransport ..... Use SecureTransport [auto] (Apple only)
 
   -sctp ................ Enable SCTP support [no]
@@ -256,6 +263,7 @@ Database options:
   -sql-<driver> ........ Enable SQL <driver> plugin. Supported drivers:
                          db2 ibase mysql oci odbc psql sqlite2 sqlite tds
                          [all auto]
+                         MYSQL_PATH= PSQL_LIBS= SYBASE= SYBASE_LIBS=
   -sqlite .............. Select used sqlite3 [system/qt]
 
 Multimedia options:

configure.json

@@ -6,6 +6,17 @@
     },
 
     "commandline": {
+        "assignments": {
+            "DBUS_HOST_PATH": "host_dbus.prefix",
+            "DBUS_PATH": "dbus.prefix",
+            "MYSQL_PATH": "mysql.prefix",
+            "OPENSSL_LIBS": "openssl.libs",
+            "OPENSSL_PATH": "openssl.prefix",
+            "PSQL_LIBS": "psql.libs",
+            "SYBASE": "tds.prefix",
+            "SYBASE_LIBS": "tds.libs",
+            "ZLIB_LIBS": "zlib.libs"
+        },
         "options": {
             "prefix": "string",
             "hostprefix": "string",
@@ -421,7 +432,8 @@
             "description": "D-Bus >= 1.2 (host)",
             "export": "",
             "sources": [
-                { "type": "pkgConfig", "host": true, "args": "dbus-1 >= 1.2" }
+                { "type": "pkgConfig", "host": true, "args": "dbus-1 >= 1.2" },
+                { "libs": "", "comment": "placeholder for DBUS_HOST_PATH" }
             ]
         },
         "libinput": {
@@ -2447,7 +2459,8 @@ XKB configuration data. This is required for keyboard input support."
         },
         {
             "type": "note",
-            "condition": "features.openssl-linked && libs.openssl.source != 0",
+            "condition": "features.openssl-linked && libs.openssl.source != 0
+                          && input.openssl.prefix == '' && input.openssl.libs == ''",
             "message": "When linking against OpenSSL, you can override the default
 library names through OPENSSL_LIBS.
 For example:

mkspecs/features/qt_configure.prf

@@ -123,6 +123,7 @@ defineTest(qtConfCommandline_string) {
     val = $${2}
     isEmpty(val): val = $$qtConfGetNextCommandlineArg()
 
+    # Note: Arguments which are variable assignments are legit here.
     contains(val, "^-.*")|isEmpty(val) {
         qtConfAddError("No value supplied to command line option '$$opt'.")
         return()
@@ -139,7 +140,7 @@ defineTest(qtConfCommandline_optionalString) {
     val = $${2}
     isEmpty(val) {
         v = $$qtConfPeekNextCommandlineArg()
-        contains(v, "^-.*")|isEmpty(v): \
+        contains(v, "^-.*|[A-Z_]+=.*")|isEmpty(v): \
             val = "yes"
         else: \
             val = $$qtConfGetNextCommandlineArg()
@@ -157,7 +158,7 @@ defineTest(qtConfCommandline_addString) {
     val = $${2}
     isEmpty(val): val = $$qtConfGetNextCommandlineArg()
 
-    contains(val, "^-.*")|isEmpty(val) {
+    contains(val, "^-.*|[A-Z_]+=.*")|isEmpty(val) {
         qtConfAddError("No value supplied to command line option '$$opt'.")
         return()
     }
@@ -189,6 +190,19 @@ defineTest(qtConfParseCommandLine) {
             next()
         }
 
+        contains(c, "([A-Z_]+)=(.*)") {
+            opt = $$replace(c, "^([A-Z_]+)=(.*)", "\\1")
+            val = $$replace(c, "^([A-Z_]+)=(.*)", "\\2")
+            var = $$eval(config.commandline.assignments.$${opt})
+            isEmpty(var) {
+                qtConfAddError("Assigning unknown variable '$$opt' on command line.")
+                return()
+            }
+            config.input.$$var = $$val
+            export(config.input.$$var)
+            next()
+        }
+
         # parse out opt and val
         contains(c, "^--?enable-(.*)") {
             opt = $$replace(c, "^--?enable-(.*)", "\\1")
@@ -353,14 +367,60 @@ defineTest(qtConfSetupLibraries) {
             }
         }
     }
+
+    # reverse mapping for assignments on command line.
+    for (a, config.commandline.assignments._KEYS_) {
+        apfx = config.commandline.assignments.$${a}
+        ra = config.commandline.rev_assignments.$$eval($$apfx)
+        $$ra = $$a
+        export($$ra)
+    }
 }
 
 # the library is specified inline in a 'libs' field.
-# this source type cannot fail.
+# overrides from the command line are accepted.
 defineTest(qtConfLibrary_inline) {
     lib = $$eval($${1}.library)
     !defined($${1}.libs, var): \
         error("'inline' source in library '$$lib' does not specify 'libs'.")
+
+    # direct libs. overwrites inline libs.
+    defined(config.input.$${lib}.libs, var) {
+        $${1}.libs = $$eval(config.input.$${lib}.libs)
+        export($${1}.libs)
+    }
+
+    # build-specific direct libs. overwrites inline libs.
+    vars =
+    any = false
+    all = true
+    for (b, $${1}.builds._KEYS_) {
+        iv = $${lib}.libs.$${b}
+        vars += $$eval(config.commandline.rev_assignments.$${iv})
+        defined(config.input.$${iv}, var) {
+            $${1}.builds.$${b}.libs = $$eval(config.input.$${iv})
+            export($${1}.builds.$${b}.libs)
+            any = true
+        } else {
+            all = false
+        }
+    }
+    $$any:!$$all {
+        qtConfAddError("Either none or all of $$join(vars, ", ", [, ]) must be specified.")
+        return(false)
+    }
+
+    # prefix. prepends to (possibly overwritten) inline libs.
+    prefix = $$val_escape(config.input.$${lib}.prefix)
+    !isEmpty(prefix) {
+        $${1}.includedir = $$prefix/include
+        export($${1}.includedir)
+        $${1}.cflags = -I$$prefix/include
+        export($${1}.cflags)
+        $${1}.libs = "-L$$prefix/lib $$eval($${1}.libs)"
+        export($${1}.libs)
+    }
+
     return(true)
 }