OpenModelica · sjoelund · Sep 27, 2026 · Sep 27, 2026
diff --git a/.CI/Jenkinsfile b/.CI/Jenkinsfile
@@ -38,7 +38,7 @@ pipeline {
     booleanParam(name: 'wasm_jit', defaultValue: false, description: 'master branch, with --simCodeTarget=wasm-jit (ryzen-9950x). Every model is translated and simulated the way simulate() does, filling wasm-jit. This is an experimental job that does not run on a fixed schedule.')
     booleanParam(name: 'wasm_web', defaultValue: false, description: 'master branch, with --simCodeTarget=wasm-jit (ryzen-9950x), simulated the way the web omc does: the driver and the linear and nonlinear solvers in wasm, the in-wasm libm, and external "C" only from prebuilt wasm libraries. Fills wasm-web. This is an experimental job that does not run on a fixed schedule.')
     booleanParam(name: 'wasm_fmu', defaultValue: false, description: 'master branch, with --simCodeTarget=wasm-jit (ryzen-9950x). Every model is exported once as an unzipped wasm FMU and simulated through both of its FMI 3.0 interfaces, filling wasm-jit-me (Model Exchange) and wasm-jit-cs (Co-Simulation). This is an experimental job that does not run on a fixed schedule.')
-    booleanParam(name: 'c_plus_rust', defaultValue: false, description: 'master branch, with --simCodeTarget=C+Rust, filling c-plus-rust (ryzen-5950x-1). The C code generator emits what it always did; the executable links libSimulationRuntimeRust instead of libSimulationRuntimeC, so the difference against master is the simulation runtime alone. This is an experimental job that does not run on a fixed schedule.')
+    booleanParam(name: 'c_old', defaultValue: false, description: 'master branch, with --simCodeTarget=C.old, filling c-old (ryzen-9950x). The C code generator emits what it does for --simCodeTarget=C; the executable links the old libSimulationRuntimeC instead of libSimulationRuntimeRust, so the difference against master is the simulation runtime alone. This is an experimental job that does not run on a fixed schedule.')
     booleanParam(name: 'heavy_tests', defaultValue: false, description: 'master branch, runs one test at a time. That is, no parallel launching of tests. omc will use multiple threads for each test (-n=1 is not set unlike the other regression tests.), (ryzen-5950x-1). This is an experimental job that does not run on a fixed schedule.')
 
     string(name: 'pull_request', defaultValue: '', description: 'Test an OpenModelica pull request rather than a branch: its number, e.g. 16354. omc is built from refs/pull/<N>/merge - the pull request as it would land - the results fill a pr-<N> table, and the report compares them against the newest run of pull_request_baseline. Left empty, nothing of this runs.')
@@ -387,7 +387,7 @@ pipeline {
           }
         }
       }
-      stage('C+Rust') {
+      stage('C.old') {
         agent {
           node {
             label 'ryzen-9950x'
@@ -397,15 +397,10 @@ pipeline {
         options { skipDefaultCheckout() }
         when {
           beforeAgent true
-          expression { params.c_plus_rust }
+          expression { params.c_old }
         }
         steps {
-          // A cmake build rather than the autotools one every other C target uses:
-          // libSimulationRuntimeRust is a cmake target (SimulationRuntime/rust), opt-in
-          // through OM_ENABLE_RUST_SIM_RUNTIME, and without it the generated makefile
-          // has nothing to link.
-          runRegressiontest('master', 'c-plus-rust', 'setCommandLineOptions("--simCodeTarget=C+Rust")', '', false, '', '', false, false, 0, 'configs/conf.json',
-                            '-DOM_ENABLE_RUST_SIM_RUNTIME=ON -DCMAKE_C_COMPILER_LAUNCHER=sccache -DCMAKE_CXX_COMPILER_LAUNCHER=sccache')
+          runRegressiontest('master', 'c-old', 'setCommandLineOptions("--simCodeTarget=C.old")', '', false, '', '', false, false)
         }
       }
       stage('generateSymbolicJacobian') {
@@ -502,7 +497,7 @@ pipeline {
       }
       when {
         beforeAgent true
-        expression { params.v1_25 || params.v1_26 || params.v1_27 || params.master || params.conversion_script || params.report_ryzen_5950x_1 || params.report_ryzen_5950x_2 || params.newInst_newBackend || params.generateSymbolicJacobian || params.heavy_tests || params.fmi_v1_25 || params.fmi_v1_26 || params.fmi_v1_27 || params.fmi_master || params.fmpy_fmi_v1_25 || params.fmpy_fmi_v1_26 || params.fmpy_fmi_v1_27 || params.fmpy_fmi_master || params.newInst_daeMode || params.newBackend_daeMode || params.oldInst || params.cpp || params.cvode || params.gbode || params.ida || params.wasm_jit || params.wasm_fmu || params.wasm_web || params.c_plus_rust}
+        expression { params.v1_25 || params.v1_26 || params.v1_27 || params.master || params.conversion_script || params.report_ryzen_5950x_1 || params.report_ryzen_5950x_2 || params.newInst_newBackend || params.generateSymbolicJacobian || params.heavy_tests || params.fmi_v1_25 || params.fmi_v1_26 || params.fmi_v1_27 || params.fmi_master || params.fmpy_fmi_v1_25 || params.fmpy_fmi_v1_26 || params.fmpy_fmi_v1_27 || params.fmpy_fmi_master || params.newInst_daeMode || params.newBackend_daeMode || params.oldInst || params.cpp || params.cvode || params.gbode || params.ida || params.wasm_jit || params.wasm_fmu || params.wasm_web || params.c_old}
       }
       environment {
         GITBRANCHES = 'maintenance/v1.20 maintenance/v1.21 maintenance/v1.22 maintenance/v1.23 maintenance/v1.24 maintenance/v1.25 maintenance/v1.26 maintenance/v1.27 master newInst-newBackend'
@@ -512,13 +507,8 @@ pipeline {
         GITBRANCHES_NEWBACKEND_DAE = 'newBackend-daeMode'
         GITBRANCHES_CPP = 'v1.19-cpp v1.20-cpp v1.21-cpp v1.22-cpp v1.23-cpp v1.24-cpp v1.25-cpp cpp v1.26-cpp v1.27-cpp'
         GITBRANCHES_WASM_JIT = 'wasm-jit-me wasm-jit-cs wasm-jit wasm-web'
-        GITBRANCHES_C_PLUS_RUST = 'c-plus-rust'
+        GITBRANCHES_C_OLD = 'c-old'
         GITBRANCHES_SPECIAL = 'master newInst-newBackend'
-        // The C+Rust job ran a few times before it was added to this stage, so
-        // it is past the run count all-reports.py takes for a first report and
-        // gets no history without being named here. Drop it once the branch has
-        // one; the run says so in its log.
-        NEWBRANCHES = '--new-branch=c-plus-rust'
         PYTHONIOENCODING = 'utf-8'
         IDA_EMAIL = credentials('IDA email')
         // A secret file holding one pgpass line; libpq reads the password from
@@ -538,8 +528,8 @@ pipeline {
         '''
         sh './clean-empty-omcversion-dates.py'
 
-        sh "./all-reports.py --email ${env.NEWBRANCHES} --omcgitdir=OpenModelica ${env.GITBRANCHES} ${env.GITBRANCHES_FMI} ${env.GITBRANCHES_NEWINST} ${env.GITBRANCHES_DAE} ${env.GITBRANCHES_NEWBACKEND_DAE} ${env.GITBRANCHES_CPP} ${env.GITBRANCHES_WASM_JIT} ${env.GITBRANCHES_C_PLUS_RUST} conversion heavy_tests generateSymbolicJacobian gbode cvode ida"
-        sh "./all-plots.py ${env.GITBRANCHES} ${env.GITBRANCHES_FMI} ${env.GITBRANCHES_NEWINST} ${env.GITBRANCHES_DAE} ${env.GITBRANCHES_NEWBACKEND_DAE} ${env.GITBRANCHES_CPP} ${env.GITBRANCHES_WASM_JIT} ${env.GITBRANCHES_C_PLUS_RUST} conversion heavy_tests generateSymbolicJacobian gbode cvode ida"
+        sh "./all-reports.py --email --omcgitdir=OpenModelica ${env.GITBRANCHES} ${env.GITBRANCHES_FMI} ${env.GITBRANCHES_NEWINST} ${env.GITBRANCHES_DAE} ${env.GITBRANCHES_NEWBACKEND_DAE} ${env.GITBRANCHES_CPP} ${env.GITBRANCHES_WASM_JIT} ${env.GITBRANCHES_C_OLD} conversion heavy_tests generateSymbolicJacobian gbode cvode ida"
+        sh "./all-plots.py ${env.GITBRANCHES} ${env.GITBRANCHES_FMI} ${env.GITBRANCHES_NEWINST} ${env.GITBRANCHES_DAE} ${env.GITBRANCHES_NEWBACKEND_DAE} ${env.GITBRANCHES_CPP} ${env.GITBRANCHES_WASM_JIT} ${env.GITBRANCHES_C_OLD} conversion heavy_tests generateSymbolicJacobian gbode cvode ida"
 
         // Recorded and announced only once they are up: a report the database
         // knows about is never generated again, so one that a later failure in
@@ -611,18 +601,13 @@ pipeline {
         // simulation path, the two FMI 3.0 interfaces of one exported wasm FMU,
         // which share an export and differ only in simulation and verification,
         // and the web omc's in-wasm path.
-        sh "./report.py --branches='master ${env.GITBRANCHES_C_PLUS_RUST} ${env.GITBRANCHES_WASM_JIT}' configs/conf.json"
+        sh "./report.py --branches='master ${env.GITBRANCHES_WASM_JIT}' configs/conf.json"
         sh "mv overview.html overview-wasm-jit.html"
 
-        // Against master, which the job shares a machine and a compiler with: the
-        // simulation runtime is the only thing that differs.
-        sh "./report.py --branches='${env.GITBRANCHES_C_PLUS_RUST} master' configs/conf.json"
-        sh "mv overview.html overview-c-plus-rust.html"
-
         sh "./report.py --branches='${env.GITBRANCHES_CPP}' configs/conf.json"
         sh "mv overview.html overview-c++.html"
 
-        sh "./report.py --branches='${env.GITBRANCHES}' configs/conf.json"
+        sh "./report.py --branches='${env.GITBRANCHES} ${env.GITBRANCHES_C_OLD}' configs/conf.json"
 
         sh 'date'
         sh 'find overview*.html history -type f | wc -l'

diff --git a/README.md b/README.md
@@ -370,22 +370,18 @@ entry there (`simflags` is what is appended to the model's simulation flags,
 `--wasmfmu`, `--fmisimulator` and `--solver` each fan one build out into
 several result branches, so a job uses one of them, not several.
 
-### The Rust simulation runtime under the C code generator
+### The old C simulation runtime
 
-`--simCodeTarget=C+Rust` emits the sources `--simCodeTarget=C` emits and links
-`libSimulationRuntimeRust` instead of `libSimulationRuntimeC`, so a run against
-master differs in the simulation runtime and nothing else.
+`--simCodeTarget=C` links `libSimulationRuntimeRust`; `--simCodeTarget=C.old`
+emits the same sources and links the old `libSimulationRuntimeC`, so a run
+against master differs in the simulation runtime and nothing else.
 
 ```bash
-./test.py --branch=c-plus-rust --extraflags='--simCodeTarget=C+Rust' configs/myConf.json
-./report.py --branches="c-plus-rust master"
-# the overview.html it writes is published as overview-c-plus-rust.html
+./test.py --branch=c-old --extraflags='--simCodeTarget=C.old' configs/myConf.json
+./report.py --branches="master c-old"
 ```
 
-The runtime is a cmake target of the OpenModelica build
-(`SimulationRuntime/rust`, `OM_ENABLE_RUST_SIM_RUNTIME`, on by default where
-cargo is installed) and has no autotools equivalent, so omc has to be built with
-cmake or the generated makefile finds nothing to link.
+The Jenkins job lists it as a column of the default overview.html.
 
 ### One build, several solvers
 

diff --git a/shared.py b/shared.py
@@ -76,8 +76,8 @@ def fixData(data,abortSimulationFlag,alarmFlag,overrideDefaults,defaultCustomCom
     data["libraryVersion"] = data.get("libraryVersion") or "default"
     data["libraryVersionLatestInPackageManager"] = data.get("libraryVersionLatestInPackageManager") or False
     data["libraryVersionExactMatch"] = data.get("libraryVersionExactMatch") or False
-    data["alarmFlag"] = data.get("alarmFlag") or (alarmFlag if data["simCodeTarget"] in ("C","C+Rust","wasm-jit") else "")
-    data["abortSlowSimulation"] = data.get("abortSlowSimulation") or (abortSimulationFlag if data["simCodeTarget"] in ("C","C+Rust","wasm-jit") else "")
+    data["alarmFlag"] = data.get("alarmFlag") or (alarmFlag if data["simCodeTarget"] in ("C","C.old","wasm-jit") else "")
+    data["abortSlowSimulation"] = data.get("abortSlowSimulation") or (abortSimulationFlag if data["simCodeTarget"] in ("C","C.old","wasm-jit") else "")
     data["simFlags"] = simulationFlags(data, data["ulimitExe"])
     if "changeHash" in data: # Force rebuilding the library due to change in the testing script
       data["changeHash"] = data["changeHash"]

diff --git a/testmodel.py b/testmodel.py
@@ -484,7 +484,7 @@ def uncaughtException(exctype, value, tb):
 with open(errFile, 'a+') as fp:
   fp.write("Running: %s\n" % " ".join(sys.argv))
 
-if conf["simCodeTarget"] not in ["Cpp","C","C+Rust","wasm-jit"]:
+if conf["simCodeTarget"] not in ["Cpp","C","C.old","wasm-jit"]:
   with open(errFile, 'a+') as fp:
     fp.write("Unknown simCodeTarget in %s" % conf["simCodeTarget"])
   writeResultAndExit(1)
@@ -674,7 +674,7 @@ def wasmJitAcceptsFlag(flagVal):
 except:
   # omc answers nothing when the call fails, and nothing else reads the buffer.
   raise Exception("%s failed:\n%s" % (cmd, omc.sendExpression("getErrorString()", parsed = False)))
-if conf["simCodeTarget"] in ("C","C+Rust","wasm-jit") and sendExpressionOldOrNew('classAnnotationExists(%s, __OpenModelica_simulationFlags)' % conf["modelName"]):
+if conf["simCodeTarget"] in ("C","C.old","wasm-jit") and sendExpressionOldOrNew('classAnnotationExists(%s, __OpenModelica_simulationFlags)' % conf["modelName"]):
   for flag in sendExpressionOldOrNew('getAnnotationNamedModifiers(%s,"__OpenModelica_simulationFlags")' % conf["modelName"]):
     if flag=="The searched annotation name not found":
       # Old, stupid API
@@ -990,7 +990,7 @@ def simulateExecutable(name, solverFlags, resFile, simFile):
   # sparsity patterns are all read from the build directory, not from here.
   setupArgument = "-inputPath=.." if runDir else ""
   cmd = inRunnerDir(runDir, " ".join(x for x in (exe, annotationSimFlags, conf["simFlags"], emit_protected,
-                             "-lv LOG_STATS" if conf["simCodeTarget"] in ("C","C+Rust") else "",
+                             "-lv LOG_STATS" if conf["simCodeTarget"] in ("C","C.old") else "",
                              setupArgument, resultArgument, solverFlags) if x.strip()))
   with open(simFile,"w") as fp:
     fp.write("Environment - simulationEnvironment:\n")

diff --git a/testresults.md b/testresults.md
@@ -10,7 +10,10 @@
   improvements in green.
 
   - [Default settings](https://libraries.openmodelica.org/branches/overview.html):
-    simulation with C runtime and default settings
+    simulation with the C code generator and default settings. Its `c-old`
+    column is master with `--simCodeTarget=C.old`: the same generated C sources
+    linked against the old `libSimulationRuntimeC` instead of the Rust
+    simulation runtime
   - [daeMode](https://libraries.openmodelica.org/branches/overview-dae.html):
     simulation with daeMode (compiler flag
     [--daeMode](https://openmodelica.org/doc/OpenModelicaUsersGuide/latest/omchelptext.html#omcflag-daemode))
@@ -26,11 +29,6 @@
     `wasm-jit-me` and `wasm-jit-cs` come from a second job that exports each
     model once as a wasm FMU and drives that one FMU through its FMI 3.0 Model
     Exchange and Co-Simulation interfaces
-  - [C+Rust](https://libraries.openmodelica.org/branches/overview-c-plus-rust.html):
-    simulation with the Rust runtime under the C code generator (compiler flag
-    `--simCodeTarget=C+Rust`). The generated sources are the ones the C target
-    emits; the executable links `libSimulationRuntimeRust` instead of
-    `libSimulationRuntimeC`, so the difference against master is the runtime alone
 
 - **Regression reports and history plots**:
   Regression reports are periodically generated, using the latest development